Transcript
Summary report
Improved indoor climate and efficient energy use in educational buildings
Ove Mørck Cenergia Energy Consultants May 2002 Report from the EU-THERMIE project: MEDUCA – Model Educational buildings for energy efficient integrated design. An Integrated Quality Targeted Project in the fields of Rational Use of Energy in Buildings and integration of Renewable Energies in Buildings BU-1006/96
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Foreword Energy use in buildings needs to be reduced for two good reasons: Continued high consumption is a treat to the environment and energy resources are limited and running out. The overall aim of the MEDUCA-project, co-funded by the EU - Directorate XVII for Energy Thermie Programme, has been to demonstrate that energy efficient educational buildings, where the requirements for an attractive and healthy indoor environment are fulfilled, can be designed and built. This was to be achieved for both new construction and refurbishment projects. The aim was to create educational buildings, which will stand out as exemplary models of optimised integrated energy efficient design for new schools to be build or refurbished in the city/region where they are located, and which can also serve as the basis for the development of improved standards for this type of buildings in Europe. The MEDUCA project encompassed eight demonstration projects in seven countries: Grong School, Norway - new construction Hökegård School, Sweden – refurbishment Tånga School, Sweden - refurbishment Egebjerg School, Denmark - refurbishment Wittorfer School, Germany - refurbishment University of Almeria, Spain – refurbishment European Public Law Centre, Lavrion, Greece - new construction Environmental Education Centre, Bagheria, Italy - new construction Of these 8 projects 7 have been completed within the time frame of the MEDUCA project. The 8th project, Environmental Education Centre, Bagheria, Italy is still pending, construction is expected with the next few years. In the course of the MEDUCA cooperation project design studies have been completed, the projects have been described, monitored and evaluated. The results of these activities has been compiled, organised and disseminated through a series of 3 thematic reports covering x ventilation, x lighting x control. These three reports will present building designers with the results of the design studies and the evaluation of the monitored data of the building projects. Besides a summary report describing each project aimed at decision makers has been produced. Finally, as part of a separate dissemination project, D_MEDUCA: An educational training kit for school teachers on the teaching of energy efficiency and RE by the use of the technologies employed on the 5 schools has been produced. All material from the project has been included on a project presentation CD-ROM, which also holds a powerpoint presentation of the projects, as well as further documentation about and illustrations of the project including a scrap book of material produced as part of the dissemination activities of the various projects. A heartfelt Thank you to all colleagues and friends that have been involved in the MEDUCA project and all have their share in the success of the project. May, 2002 Ove Mørck, Co-ordinator
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List of contents 1
INTRODUCTION................................................................ 6
2
EXECUTIVE SUMMARY ................................................... 6
2.1
Aim and objectives .....................................................................................6
2.2
Conclusions .................................................................................................6
2.3
Indoor climate.............................................................................................8
2.4
Costs – benefits ...........................................................................................8
2.5
Overall benefits...........................................................................................9
2.6
Required R&D&D......................................................................................9
2.7
Success as demonstration projects ..........................................................10
2.8
Project process documentation ...............................................................10
3
THE DEMONSTRATED TECHNOLOGIES ..................... 11
4
THE GRONG SCHOOL ................................................... 13
4.1
Description of the project ........................................................................13
The energy saving concept and the technologies..................................................15 4.3
Energy savings and reduced emissions...................................................19
4.4
Evaluation of indoor environment ..........................................................20
4.5
Costs...........................................................................................................22
4.6
Conclusions and lessons learned .............................................................22
Key project data......................................................................................................24 4.8
5
References .................................................................................................24
HÖKEGÅRD SCHOOL, SWEDEN – REFURBISHMENT 26
5.1
Description of the project ........................................................................26
5.2
The energy saving concept and the technologies ...................................28
5.3
Energy savings and reduced emissions...................................................29
5.4
Evaluation of indoor environment ..........................................................31
5.5
Cost benefits..............................................................................................32
4
5.6
Conclusions and lessons learned .............................................................34
5.7
Key project data .......................................................................................35
5.8
References .................................................................................................36
6
TÅNGA SCHOOL, SWEDEN – REFURBISHMENT........ 38
6.1
Description of the project ........................................................................38
6.2
The energy saving concept and the technologies ...................................39
6.3
Energy savings and reduced emissions...................................................42
6.4
Evaluation of indoor environment ..........................................................44
6.5
Cost benefits..............................................................................................46
6.6
Overall conclusions/lessons learned (design concept) ...........................48
6.7
Key project data .......................................................................................49
6.8
References .................................................................................................50
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EGEBJERG SCHOOL, DENMARK................................. 53
7.1
Description of the project ........................................................................53
7.2
The energy saving concept and the technologies ...................................55
7.3
Energy savings and reduced emissions...................................................59
7.4
Evaluation of indoor environment ..........................................................61
7.5
Cost benefits..............................................................................................62
7.6
Conclusions and lessons learned .............................................................62
7.7
Key project data .......................................................................................63
7.8
References .................................................................................................63
8
THE WITTORF SCHOOL ................................................ 66
8.1
Description of the project ........................................................................66
8.2
The energy saving concept and the technologies ...................................67
8.3
Energy savings and reduced emissions...................................................71
8.4
Evaluation of the indoor environment....................................................75
8.5
Cost benefits..............................................................................................75
8.6
Conclusions and lessons learned .............................................................76
8.7
Key project data .......................................................................................76
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UNIVERSITY OF ALMERÍA, SPAIN................................ 77
9.1
Description of the project technical and architectural..........................77
9.2
The energy saving concept and the technologies ...................................79
9.3
Evaluation of performance (evaluation & monitoring ) ......................80
9.4
Evaluation of indoor environment ..........................................................84
9.5
Cost benefits..............................................................................................85
9.6
Overall conclusions/problems encountered/lessons learned .................86
10 THE ENVIRONMENTAL EDUCATION CENTRE OF MONTE CATALFANO, BAGHERIA, ITALY........................... 87 10.1
Description of the project ......................................................................87
10.2
The energy saving concept and the technologies...................................89
10.3
Energy savings and reduced emissions..................................................91
10.4
Evaluation of indoor environment .........................................................94
10.5
Cost benefits ..........................................................................................95
10.6
Key project data.....................................................................................96
10.7
References .............................................................................................96
11 EPLC PREMISES ............................................................ 97 11.1
Description of the project....................................................................97
The energy saving concept and the technologies..................................................98 11.3
Energy savings and reduced emissions ............................................102
11.4
Evaluation of indoor environment ...................................................103
11.5
Cost benefits .......................................................................................105
11.6
Conclusions and lessons learned.......................................................105
11.7
Key project data.................................................................................106
12 REFERENCES............................................................... 107 12.1
Litterature ..........................................................................................107
12.2
Other projects with the same focus ..................................................108
13 APPENDIX 1: MEDUCA SCRAP BOOK....................... 109
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1
Introduction
The building sector is the sector with the highest energy use in Europe. New educational buildings will be built and existing are being and will be refurbished - very often with improved indoor environment as an objective. It is important to show the public and the building professionals – both designers and building owners - that it is possible to improve comfort and at the same time reduce energy consumption in a cost-effective way. The main characteristic of an educational building is the intermittent occupancy and the many different functions it must provide rooms for. An educational building can contain classrooms, auditory, a library, a café, a gymnasium, laboratories, office spaces etc.. The requirements on educational buildings can be different, but some basic requirements are important to ensure a good learning environment for all educational buildings: the need for fresh air, light and thermal comfort. By introducing energy efficient, healthy and environment friendly schools we are setting a good example for our students, pupils, teachers, parents, decision makers, engineers, and architects. Being in an energy efficient and healthy building during the learning process, the students and pupils will also learn about energy efficient and healthy buildings. 2
Executive summary
2.1 Aim and objectives The overall aim of the MEDUCA-project was to demonstrate that energy efficient educational buildings, where the requirements for an attractive and healthy indoor environment are fulfilled, can be designed and constructed in new as well retrofitting projects. The objective of the MEDUCA project was to create educational buildings, which will stand out as exemplary models of optimised integrated energy efficient design for new schools to be build or refurbished in the city/region where they are located, and which can also serve as the basis for the development of improved standards for this type of buildings in Europe. Specifically it was the aim that the penetration of an integrated quality technological approach to energy efficient design of educational buildings as standard practice at local level and in the home countries of the MEDUCA projects will be the result of this co-operation. The implementation of innovative technologies in tangible, visible building projects was considered an optimal way of dissemination information about these technologies and their potential. 2.2
Conclusions
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2.2.1 The demonstration projects In the course of the MEDUCA project 8 demonstration projects of educational buildings were designed and 7 built, monitored and evaluated. The eight demonstration projects are: 1. Grong School, Norway - new construction 2. Hökegård School, Sweden – refurbishment 3. Tangå School, Sweden – refurbishment 4. Egebjerg School, Denmark - refurbishment 5. Wittorfer School, Germany - refurbishment 6. University of Almeria, Spain - refurbishment 7. Environment Education Centre, Italy – new construction 8. European Public Law Centre, Greece - new construction As is seen 5 of these are refurbishments (DK, D, S, S, E) and 2 new constructions (N, GR) – that is 3 if the Italian project is counted. The 7th project (Italy) had the analyses and design phases undertaken within the time frame of the MEDUCA project but not the construction, monitoring and evaluation phases. The projects from each country are described in individual chapters in this report. 2.2.2 Energy & environment The aim for the demonstration projects was based on a total energy optimisation to reduce the yearly use of thermal energy for space and hot water heating and cooling, and at the same time obtain considerable savings of electricity. Also renewable energy sources are utilised in the project ranging from conventional liquid solar collector systems, via transpired air solar collectors for preheating of air to advanced integrated PV-systems. Table 2.1 Overall energy savings
Project
1. Grong, N 2. Hökegård, S 3. Tånga, S 4. Egebjerg, DK 5. Wittorfer, D 6. UalM, E 7. EPLC, Gr Total
Saved thermal energy, MWh/year 20 205 205 161 600 17 65 1273
Saved electricity,
Total saved energy, MWh/year MWh/year 16 36 46 251 46 251 24 185 27 627 8 25 55 120 222 1495
Based on the energy savings reported by the individual projects table 2.1 has been compiled to provide an overview of the total savings achieved within the MEDUCA project. According to Table 2.1 the total energy savings in the 7 completed MEDUCA projects are in the order of 1,5 Gwh/year.
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An estimate of the total reduced emissions caused by these energy savings is not straightforward, as for example the electricity consumption in Norway comes from hydro power, and the thermal energy is to be produced by a biomass plant. Generally factors for CO2 and other emssions differ from country to country. When approximative general factors for European countries are adopted (205 t/GWh heating and 865 t/GWh electricity) the above savings has resulted in reduced CO2 – emissions of 453 tons per year, corresponding to an average reduction of 50%. 2.3
Indoor climate
2.3.1 Air quality - ventilation The thematic report on ventilation accounts for the design studies and experiences with the implemented ventilation systems. The general user feed back from the projects match well with the measurements taken for CO2 – levels: The indoor air quality has significantly improved in all renovated projects and is very good in the new built projects. The innovative hybrid/natural ventilation systems combined with the use of low-emitting materials have proven successful. 2.3.2 Light quality - lighting The Meduca project has resulted in a separate thematic report on lighting. In this report the daylighting and artificial lighting systems, their design and results from monitoring and evaluation are presented. The overall conclusion in this report is that the quality of light is high in the MEDUCA projects and that considerable savings has been achieved due to innovative daylighting systems and efficient artificial lighting and control systems. 2.4
Costs – benefits
2.4.1 Project economic payback periods The cost-efficiency expressed as simple payback times in years has been estimated for 5 of the 7 demonstration projects. For 3 of them a payback time of around 13 years were quoted: Wittorf school, University of Almeria and European Public Law Centre. For the Tånga school in Sweden a payback time of 17 years has been calculated and for the Egebjerg school in Denmark 37 years is estimated. The variation is considerable. Everyone involved within the building industry knows that cost calculations are often very difficult to deal with, as the cost of a certain building element varies from case to case. Or part of the cost can be ascribed to an element that was warn out and had to be replaced anyway – in this case the real cost is the marginal cost of the more energy efficient component compared to a standard component selected just to fulfil the building requirements.
2.4.2 Cost efficiency of EU support. The overall budgets for the 7 completed construction projects exceeded 9 M Euro of which 4 M Euro was used especially for energy saving measures. The total support received from the EU THERMIE
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programme was 1,6 M Euro. As mentioned above the 7 projects in total save 1,5 GWh/year of energy and the reduced emissions is estimated to 453 tons of CO2/year and corresponding amounts of other emissions. Seen over a 25 year period this corresponds to 23,4 kWh and 7 kg CO2 per Euro supported by EU. 2.4.3 ESCO business potential “While the physical state of our nation’s school declines, studies show that the state of the physical plant can have a direct effect on the quality of the education enjoyed by students using the facility. In addition to students’ ability to learn, deferred equipment maintenance and repairs result in wasted energy, increasing long term costs for already overburdened school budgets.” This strong statement introduces an American report on the potential for improving the learning environment and at the same time save energy (see References – literature: comfort and cost). The situation in Europe corresponds very well with this statement and the results obtained in the MEDUCA demonstration projects confirm that this potential exist and can be harvested. Often a limited annual school building budget constraints the school administrations authority and constitutes a real barrier for carrying through the necessary improvements in building fabric and systems. There is an obvious possibility for the private Energy Service Companies to take over the energy supply of school buildings, invest for is required to improve the indoor environment and to save energy and depreciate the investment over a longer period, than what is possible for most public authorities. The design studies conducted for the MEDUCA demonstration projects and the undertaken evaluation documents the cost-efficiency of the implemented technologies and can be used as background information for future energy retrofit projects within the educational building sector. 2.5 Overall benefits Educational buildings are often a meeting point not only for students and pupils, which means that schools have a demonstrative effect on others as well. Being very visible in the society educational building get a lot of public attention and are therefore ideally suited for demonstration purposes. As a result more and more people will demand energy efficient, healthy and environment friendly buildings of all types. 2.6 Required R&D&D The implementation of innovative technologies for ventilation and lighting are often met by barriers due to conventional thinking and building requirements. For example, traditional thinking with respect to thermal comfort are based on fully air-conditioned or mechanically ventilated rooms. Also recent investigations show that in daylight, people tend to accept lower lux levels than specified in the lighting standards. There is a clear need for new research activities clarifying comfort requirements in naturally ventilated and lit rooms.
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There is a need for the development and refinement of design guidelines for natural ventilation design. Case studies should be presented, and recommendations should be given along with such guidelines. All components in the airflow path should be dealt with; also the design of underground air intake ducts and exhaust towers. In addition, there is a need for development of air handling equipment. Some of the existing ventilation system components should be tested for low pressure drop in order to learn their characteristics for design. There is also a need for developing components especially for natural or hybrid ventilation. Typically, there is a need for fans for installation in intake ducts and in exhaust towers to assist natural ventilation. A wind resistant exhaust damper has been designed for the Norwegian MEDUCA project by ROOMVENT DESIGN dr.ing. Per O. Tjelflaat. The exhaust damper uses a windshield combined with self-adjusting vanes and a Venturi geometry. The design has been patented. The wind resistant exhaust damper is available through: Auranor AS, P.O. Box 100, N 2712 Brandbu, Norway, http://www.eksport.com/delt/ind/ auranor.html. There is a demand for new heat exchangers with the focus on low pressure drop and low cost for natural ventilation systems Demand controlled ventilation is even more needed in natural ventilation systems than in conventional ventilation systems as heat recovery from exhaust air is less efficient. Especially, correct placement of sensors in rooms is crucial to achieve effective and efficient climatization. 2.7 Success as demonstration projects All the MEDUCA projects have achieved great public and professional interest from as well the design community as from municipal building authorities, see Appendix 1 with project scrap book material. After completion all the projects have experienced an overwhelming interest from municipalities, architects and engineering companies, that have visited the projects and learned form the experiences gained by the projects. Several newer educational projects in the various countries represented by the MEDUCA project have been designed using the MEDUCA projects as models for the technologies chosen. Thus the schools have been accepted as role models for future educational building renovation and new constructions and requirements in new and future educational building projects are beeing written based on the standards established by the MEDUCA projects. 2.8 Project process documentation At the outset of the MEDUCA project some internal management documents were conceived to ensure a proper coordination of the project and that necessary project data were compiled. These docu-
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ment constituted a set of tables filled out fore each project – project information sheets. Also a detailed monitoring program was developed to ascertain that the necessary data for a thorough evaluation of the completed projects was available. This program was followed by all the projects. For those interested these documents can be found on the project presentation CD-ROM prepared as part of the D_MEDUCA project. 3
The demonstrated technologies
3.1.1 Integrated technologies Modern building technology, heating and ventilation technology has been combined with natural materials, natural ventilation and passive heating and cooling. The projects, have been based on a general integrated global energy efficient design concept based on total economic optimisation. The concepts employed include the use of many different innovative low energy technologies. Overleaf the innovative technologies from the participating projects are listed in a technology / project matrix. The matrix facilitates the possibility to see which technologies was implemented in each project and horizontally which projects implemented a certain technology.
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Table 3.1 Innovative technologies / project matrix for the MEDUCA project. TECHNOLOGIES/PROJECTS
Egebjerg Danmark
Wittorf Germany
Extra Insulation
X
X
X Low energy windows 1.5-2.0 W/m2 oC Super low energy windows 1.0 W/m2 oC Heat recovery of ventilation air X Hybrid /natural ventilation system X Solar preheating of ventilation air Passive solar heating
X
Passive solar cooling
Hökegård Sweden
Tånga Sweden
Bagheria Italy
EPLC Greece
X
X
X
X
X X
X
X
X
X
X
X
X
X
X
X X
X
X
X
X
X
X
X
X
X
X X
Solar room heating system Solar PV
X
X
X X
X
X
X
X
X X
X
X
X
X
Optimised daylighting System Low energy lighting (artificial) Solar control/shading
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X X
Advanced control system Energy management system Water savings
Earth/geothermal
X
X
X
X
UALM Spain
X X
X
Solar DHW system Solar air collectors
Grong Norway
X
X
X
Hökegård School
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The Grong School
by Karin Buvik. SINTEF Department of Architecture and Building Technology.
NORWAY
Fig. 4.1 Photo from September 1998 4.1 Description of the project The energy conservation and solar strategies in the Norwegian MEDUCA project was: Use of solar energy for space heating and pre-heating of ventilation air. Use of daylight to reduce the consumption of electric energy for artificial lighting. Separately operating zones for artificial lighting, and control by daylight sensors contribute to energy efficiency. Use of natural driving forces for ventilation, buoyancy and wind, result in a minimum of fan power. Further, airflow controlled by CO2 sensors, heat recovery, and low-emitting building materials contribute to energy efficiency. The new wing is a one-story school building. Classrooms are situated on the northern side of a central circulation spine. Common rooms, rooms for group activities, storage rooms, and locker rooms are located on the south side.
On the top of the building, in the attic, there is a solar collector (sunspace), which gives light to the classrooms, heat to the exhaust air and thereby extra driving forces for the ventilation air, plus heat to the intake air via the heat recovery system.
North facing classrooms have no need for glare reduction devices or shading systems, but have low heat gains and thus increased need for heating during winter. To increase solar gains the exhaust air chamber (top of the building) is designed as a solar collector (sun space), which gives heat to the fresh air via the heat recovery in the exhaust tower, and also gives some sunlight into the classrooms. The internal walls of the sunspace are glazed in order to allow daylight to reach the back of the classrooms. The roof monitor (sunspace) design optimises passive solar heating and even distribution of daylight on the workplaces. The new building was completed in August 1998.
Hökegård School
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4.1.1 School and Community House The building complex is going to be renewed and extended. A task was to find suitable solutions for co-ordinated use between the school and the community house. Many rooms are planned for social and cultural activities, as well as for teaching and learning. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
main entrance vestibule exhibition wardrobe café homemaking amphitheatre library administration 13-15 years old 10-12 years old 6-9 years old swimming pool gym/assembly hall hall
15
5
9
8
14 11
6
2
4 13
3
2
12
1
3 10
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Fig. 4.2. After renovation. Project 4.1.2 Plan principle Homebases for the primary and lower secondary school contains classrooms, activity rooms, rooms for small groups and entrances. An objective was to create a flexible area, which may be divided into landscapes. Rooms for gatherings are obtained by the possibility of opening up between classrooms and activity rooms.
North
1 entrances 2 wardrobes 3 activity rooms 4 groups 5 training (ADL) 6 classes
.
Fig. 4.3. Plan of the new wing
Hökegård School
4.2
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The energy saving concept and the technologies
Fig. 4.4. South fasade. Primary and lower secondary school to the right
Fig. 4.5. North fasade. Primary and lower secondary school to the left
4.2.1 Solar heating A sunspace runs along the entire ridge of the building. The tilted south facing glazing was designed to optimise the use of incident solar energy over the year. The sunspace also functions as a roof monitor that transmits daylight into the classrooms; and it serves as a ventilation air exhaust chamber as well. The sunspace (solar air collector) is expected to allow for a high fraction of usable solar heat contribution. Heat loss to ventilation air represents a large portion of the heating energy requirement in cold climates. A system of indirect ventilation air pre-heating is employed. Solar radiation incident on the south facing glass of the sunspace will cause the temperature of the exhaust air to rise. The heat is recovered at the exhaust tower and exchanged to the fresh air at the underground air intake tunnel. 4.2.2 Daylighting The internal walls of the sunspace are glazed in order to allow daylight to reach the back of the classrooms. Three different methods were used to simulate the daylight levels in the classrooms. The selected roof monitor (sunspace) design optimises passive solar heating and even distribution of daylight on the workplaces. The classrooms are located on the northern side of a central circulation spine. Rooms for group activities, storage rooms, restrooms, and locker rooms are located on the south side. Model studies A model of a typical section of the building is analysed, using an artificial sky.
North facing classrooms have no need for glare reduction devices or shading systems, but have low heat gains and increased heat losses during winter.
Hökegård School
SP1
SP2
SP3
SP4
base case
SP1
Alternative Daylighting Designs Daylighting analysis was integrated with passive solar heating analysis, using an analysis model based on monthly average temperature and global radiation data. Three alternative designs were compared. First the impact on the annual combined lighting and auxiliary heating energy demand of alternative daylighting designs was investigated. In order to do a cost-benefit analysis, it was necessary to analyse the utilisation of daylight for the illumination of interior spaces. An analysis of passive solar heating to reduce the auxiliary heating energy demand was also required.
SP2
SP3
SP4
Finally, an analysis of clear-day room temperatures was performed in order to produce indicators of the thermal comfort levels of the alternative designs as compared to the base case. Based on the findings from the analysis, alternative 2 was incorporated into the final design.
alternative 1
SP1
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SP2
SP3
SP4
alternative 2
Different design alternatives showing view of the sky from four station points. North is to the right.
Artificial Lighting Controls Separately operating zones of artificial lighting is implemented in order to reduce uneven lighting levels and contribute to energy savings. Timers and daylight sensors are used to control the artificial lighting. 4.2.3 Ventilation An air inlet tower is located outside the building. The air is brought into the building through an underground tunnel that connects the air intake tower to a distribution chamber below the central circulation spine. Exhaust air is extracted through the exhaust chamber (sunspace) above the circulation spine. A centrally located exhaust tower at the top of the building provides the necessary stack effect.
Fig. 4.6. Section of the new wing
The underground supply air duct provides for pre-heating of ventilation air in the winter season through ground coupling; and precooling of the air during the summer. Increased nighttime ventilation
Hökegård School
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during overheated periods provides a significant amount of cooling energy to the building with an estimated 12-hour time lag. The supply air, which is distributed in the classrooms by displacement ventilation, is introduced at floor level through low-velocity diffusers. Warm and contaminated air rises and leaves the room at ceiling level, through controllable dampers, into the exhaust chamber. Wardrobes and toilets are provided with overflow air, and the exhaust air is being mechanically extracted from the toilets. Sunspaces in the attic In order to reduce air contamination by source, low-emitting materials has been used predominantly. Lower emissions from materials allows for a substantial reduction of the air change rate, which in turn promises a decrease in the heat loss to ventilation air during the heating season. The sunspace/exhaust air chamber was designed to assist the movement of air. The driving force represented by the hot air in the exhaust chamber reduces the need for fan assistance. This is particularly important in summer season when increased ventilation air volume is used to cool the building. The following modes have been identified: • Winter day - regular school day: Air preheated in underground duct, by heat recovery and by hydronic coil. Perimeter heaters on when needed. Room exhaust dampers controlled by CO2-level • Winter night - school closed: Perimeter heaters on when temperature gets below 15°C • Mid-season day: Same as winter day • Mid-season night: Same as winter night • Summer day: Exhaust fan starts and exhaust dampers open in situations of unsatisfactory indoor air quality or temperature level above set point. Exhaust air is led around exhaust air heat exchanger. • Summer night: Night ventilation through underground supply air duct in order to chill it’s thermal mass, which will provide precooling for the supply air on the following day; high airflow rate when high temperatures are expected.
Fan Assisted Supply and Extract Fans are installed both at the supply side and the exhaust side. The supply fan is supposed to ensure a steady air flow into the building, while the exhaust fan is used to achieve forced ventilation for cooling during summer when buoyancy forces are insufficient. A preliminary study indicated that wind-driven natural ventilation could not provide satisfactory ventilation at all times. Calm periods of 5-7 days have been reported at the site. Buoyancy-driven ventilation is considered reliable for the coldest part of the heating season, but it may not work sufficiently for summer conditions and for some periods during spring and fall. Additionally, the installed filters and heat exchangers cause an airflow pressure drop. Hence, fan-assisted buoyancy driven ventilation strategy was employed in the final design. Heating and Cooling To day the school has an electric and oil fuelled hot water heating. Connection to a planned biomass fuelled district heating system is intended. Pre-heating of supply air during the winter occurs in three steps: First by the thermal mass in the underground supply air duct, then by a heat exchanger providing heat from the heat recovery system, and finally by a hydronic coil heat exchanger. The building itself is considered as light, but brick walls between the classrooms and the circulation space, and the concrete floors, provide some thermal mass.
Hökegård School
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The solar gains from the sunspace will also add heat to the heat recovery system during spring and fall. On cold days, a net heat loss from the exhaust airflow through the glazed areas will contribute to an expected decrease in the stack effect by less than 10 %. Since the temperature of the basement distribution chamber is set at 19°C, it can be claimed that the central corridor of the building has a kind of passive radiant floor heating system. The underground supply air duct will also provide a considerable precooling of the air during the summer. However, with a design summer temperature of 23°C, the cooling demand is relatively low. Pre-cooled ventilation air may still be called for, particularly in early fall when low sun angles and predominantly clear skies could occasionally
Placing the exhaust tower The exhaust tower was constructed in a workshop and tested to secure a low pressure-drop in the airflow through heat recovery and damps. The tower was transported to Grong and placed on the school building.
Heat Recovery Heat is recovered from the exhaust air in the exhaust tower by the use of a heat exchanger. The recovered energy is then used to heat the supply air via another heat exchanger placed between the underground supply air duct and the distribution chamber. A water-glycol loop conveys the heat between the heat exchangers. The expected heat recovery rate is some 55-60 %. Expected pressure losses are 25 Pa for the inlet air exchanger and 28 Pa for the exhaust air exchanger. A considerable pre-heating of the air will also occur in the underground supply air duct, before the heat recovered from the exhaust air is added. During periods when heat recovery is not needed, the exhaust air bypasses the heat exchanger in order to avoid creating a pressure drop.
Patented dampers A wind resistant exhaust damper has been designed by ROOMVENT DESIGN dr.ing. Per O. Tjelflaat. The exhaust damper uses a windshield combined with self-adjusting vanes and a Venturi geometry. The design has been patented. The wind resistant exhaust damper is available through: Auranor AS, P.O. Box 100, N 2712 Brandbu, Norway http://www.eksport.com/delt/in d/auranor.html
Filters and Fans A mosquito net is installed in the air intake tower. Fine filter is installed at the end of the underground air inlet duct, just before the inlet heat exchanger unit. The pressure loss through it is substantial, about 20 Pa for a new filter. It is assumed that large particles will be deposited in the underground supply air duct, before reaching the fine filter. Fans are of the propeller type, having a diameter close to the inner diameter of the duct. The supply fan, which is placed in the air inlet tower, has the ability to enhance the pressure by some 70 Pa. The exhaust fan, which is placed at the lower end of the exhaust tower, will add a pressure of about 35 Pa to the system. Controls CO2 sensors control the airflow through the exhaust valves mounted in the glass wall between the classrooms and the sunspace. Temperature sensors for control of the heating system are installed. Perimeter radiant heaters are engaged during cold periods to prevent the temperature to drop below 15°C.
Hökegård School
4.3
Energy Building performance - Calculated values Electrical Energy Savings Compared to a Conventional Building • Avoided use of high grade electrical energy due to daylight responsive controls of artificial lighting: 10.2 kWh/m2 -year. • Avoided use of electricity for ventilation fans due to natural ventilation: 9.2 kWh/m2 -year. SUM: Reduced use of electricity: app. 20 kWh/ m2 -year. Thermal Energy Savings Compared to a Conventional Building • Reduced auxiliary heating energy demand due to the incorporation of a sunspace roof monitor: 6.9 kWh/ m2 -year. • Reduced demand for heating energy due to low energy windows, low emitting materials, and demand controlled, hybrid ventilation: 8.7 kWh/ m2 -year. SUM: Reduced demand for heating energy: app. 16 kWh/ m2 -year.
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Energy savings and reduced emissions
4.3.1 Recorded energy supply Recording Period: 1st August 1998 – 20th November 2000 (close to 27 months) Electric energy consumption: 46,458 kWh Delivered energy as hot water from neighbour building: 175,302 kWh The average annual energy use Electric: 46,458 . (12/27) = 20,648 kWh Oil: 175,302 . (12/27)/0.9 = 86,669 kWh An oil-fired boiler produces the hot water, and the efficiency is taken as 0.9. The specific energy use The gross useful area in the school building is 1001 m2. The heated culvert area and the exhaust duct (sunspace) area are 160 m2 each, but are not considered useful for occupants. Electric: 20,648/1001 = Oil: 86,669/1001 =
20.6 kWh/(m2 . year) 86.5 kWh/(m2 . year)
Comments to the energy consumption Electrical energy consumption is 20,648 kWh over a year. The predicted value is 12,400 kWh. Lighting is assumed to make the major part (80%). More hours of occupancy than assumed in the prediction may be a cause for the higher consumption. The BEMS make the fans run without any need for ventilation as explained below. The yearly consumption of hot water for heating is 86,669 . 0.9 = 78,002 kWh. The predicted value is 55,800 kWh. The reason for the higher consumption can probably be found in: The faulty CO2-sensor in room 125 makes the BEMS believe that there is a high level of CO2 in the room, and the system run the fans at full speed to supply more fresh air to the room. This process goes on even at night, and demands more energy to heat the supply air. The prediction has been carried out for a simplified scenario. Not accounted for are: infiltration (rather exfiltration) above 0.01 ach., thermal bridges in the envelope, heat loss from air exhausted from the restrooms and directly to outside, and heat loss from the heated part of the ventilation culvert. Actual hours and intensity for use of the building may be different to what is assumed. The heat gain and the heat loss from the glazed areas on the roof (sunspace) have been accounted for in a way that is not expected to give very accurate results.
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Several minor faults with the building itself and with the ventilation system, leading to discomfort for occupants and excessive energy consumption, were corrected in 1998/99. *
Progress report The long-term measurement logging of data from outdoor and indoor climate and from HVAC system parameters was delayed due to problems with BEMS. New software for the BEMS has been funded by NVE, and was installed in December 2000. Long-term monitoring started in January 2001. A recent review of data, collected for the period 7 March till 10 April, shows that the demand-controlled ventilation has worked very well. The energy consumption for the first 3 months of 2002 has been reduced, compared to 2001. Total consumption for the period in 2001 was 84,600 kWh while it is 65,600 in 2002. The reduction is found in the consumption of hydronic heating; a reduction from 74,400 kWh to 54,000 kWh, i.e. 27 % reduction. There seems to be a reduction in degree-days (Trondheim) of about 14 % this year compared to last year (degree-days for January and February only available at this time) that counts for a good share of the reduction in consumption. The rest of the reduction is probably due to the good functioning of the demand-controlled ventilation since December 2001.
4.3.2 CO2 emissions The electrical energy is provided by hydro power, which has no CO2 emissions. The thermal energy is today provided by oil, but the oil will in the future be replaced by biomass, which is CO2 neutral. The yearly consumption of oil corresponds to a volume of: 86,669 . 3.6/41.8/920 = 8.1 m3. 4.4 Evaluation of indoor environment The leakage of the building envelope has been measured by using the supply fan of the building. The building is considered fairly airtight compared to requirements for similar buildings. Air leakage data: 0.83 ACH@50 Pa. Estimated after test at 10 Pa overpressure in building at T=20 qC inside and outside, and no wind. The ventilation system is very easy to inspect and to clean, and a long life can be expected for the system. No shoes that are used outside the building are allowed in the classrooms.
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4.4.1 Air quality and thermal comfort The building, including the ventilation system, is capable of giving users acceptable air quality and thermal comfort in the heating season. For the summer season (cooling season), measurements have not been taken yet. However, no complaints were registered for the years 1999 and 2000. Test temperature measurement show that the intake air culvert has a cooling effect. The reading of some of the CO2 meters in the building has been compared to the reading of a very accurate analyser. The meters in the building show generally higher values than the analyser does. Some values are more than 150 PPM higher. A difference within 50 PPM was expected. The southern wall with the clerestory windows. The picture shows ventilation supply and extract devices.
It has been observed that use of asthma medicine among the pupils has diminished when the new school was taken into service. 4.4.2 Daylight conditions The building has secondary windows on the opposite wall to the window wall. The secondary windows are designed as a horizontal strip, situated just beneath the roof. They have lower transmission factor than the main windows, such that they do not dominate the room during overcast sky conditions. On sunny days they enable sunshine to enter the classroom, a very nice effect during wintertime. If sunlight penetrates the room too much, it can be diffused using the vertical louvers. The lager part of the solar radiation is then utilised for preheating the ventilation air. The distribution of daylight in the classrooms under the conditions of overcast sky is very even. A large southern part of the room has a high daylight factor of about 3 %. In the areas near the north-facing windows the daylight factor is between 8 and 9 %.
Computer simulation Simulated daylight levels for the classrooms were calculated using the SUPERLIGHT computer program developed by the Lawrence Berkeley National Laboratory. The calculated values came close to the measurements of daylight factors derived from actual measurements of illuminance levels in a model, which was placed under an artificial sky.
The users are very happy with the daylighting conditions in the classrooms. The teachers who work in those classrooms evaluated daylighting in the classrooms as very bright and very even. They did not notice any veiling reflexes or shadows that could disturb the visual environment in the classrooms. Solar glare was experienced only in one classroom, where the mechanism for adjusting the louvers did not function properly. The colours were evaluated as rather natural and the colour temperature as neutral. In spite of the fact that the sunshading used in the Grong school is very easy to use, it happens that it covers the south-facing windows unnecessarily in periods when the sun disappears but nobody changes the position of louvers or moves them to the side. Therefore, the daylight factor measurements were made a second time with vertical louvers covering the windows and adjusted to reflect sunlight back to the duct at the middle of the day. The results show that the daylight
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level is lower than for clear windows, but the mean daylight level is still higher than the level recommended by the Norwegians building code. As can be expected, the louvers shade mostly the southern part of the classroom. 4.5 Costs The total building costs are close to the average, normal costs. Building: 14 000 000 NOK in 1998, i.e. ~1 730 000 EURO. Floor area: 1 001 m2 HVAC system including BEMS, concrete culverts and intake- and exhaust tower: 1 500 000 NOK, i.e. ~185 000 EURO. Conventional ventilation ductwork has been avoided. That may not only reduce the pollution level in supply air to rooms, but it may also reduce cleaning costs. The low velocities in airflow paths and in components such as air filter and heat exchangers, results in high component costs compared to conventional ventilation systems. On the other side, fan costs are lower due to less power demand for assisted natural ventilation. A very low consumption of electrical energy for the fans is achieved. Low fan power does result in low noise production that is another important benefit compared to conventional systems. Long underground ducts may be an extra cost, but used in an area with no infiltration of moisture and radon, it will be a great advantage on hot summer days. In addition, it seems like such ducts will reduce the power installation needed for supply air heating. The duct is also used for distribution of water end electricity. 4.6
Conclusions and lessons learned
4.6.1 Ventilation A ventilation system design has been developed that works at times when stack-effect is insufficient. The largest problem for naturally ventilated buildings seems to be heat recovery from exhaust air along with low pressure-drop in the airflow. The heat-recovery units chosen for this building is a compromise between installation cost and pressure-drop. The units could have been reconsidered to allow for smaller pressure-drop, for example by using convectors located in the end of the underground intake duct that is closer to the building. Need for research and development There is clearly a need for design guidelines for natural ventilation design in Nordic countries. Case studies should be presented, and recommendations should be given along with such guidelines. All
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components in the airflow path should be dealt with; also the design of underground air intake ducts and exhaust towers. In addition, there is a need for air handling equipment. Some of the existing ventilation system components should be tested for low pressure drop in order to learn their characteristics for design. There is also a need for developing components especially for natural or hybrid ventilation. Typically, there is a need for fans for installation in intake ducts and in exhaust towers to assist natural ventilation. As there is no demand for very compact heat exchangers in natural ventilation systems, new heat exchangers with the focus on low pressure drop and low cost should be developed. Demand controlled ventilation is even more needed in natural ventilation systems than in conventional ventilation systems as heat recovery from exhaust air is less efficient. Especially, correct placement of sensors in rooms is crucial to achieve effective and efficient climatization. 4.6.2 Daylighting There is a balanced usage of daylighting apertures in the classrooms, which allow daylight to penetrate into the rooms from to sides. The northern windows, which give a cool, bluish skylight, are clearly the primary daylight sources. The daylight level in the window zone is also highest. The clerestory windows have a secondary function. Since they are placed very high in the southern wall, they distribute daylight evenly over a large part of the room, without compete with the main windows. In spite of the fact that the sunshading used in the Grong school is very easy to use, it happens that it covers the clerestory windows unnecessarily in the periods when the sun disappears but nobody changes the position of louvers or moves them to the side. A better solution for the sunshading problem could be horizontal blinds. During sun hours, the unwelcome sunlight could be reflected to the ceiling. During overcast sky hours, the horizontal blinds covering the windows would enable the skylight to penetrate the room much more than the vertical louvers do. As a result, the daylight level in the southern part of the room could be higher.
Hökegård School
Contact persons Karin Buvik, Project leader R&D SINTEF, Dep. of Architecture and Building Technology E-mail:
[email protected] Per Olaf Tjelflaat Professor HVAC, NTNU E-mail:
[email protected] Kåre Herstad Letnes Architects E-mail:
[email protected] Torbjørn Landsem HVAC consultant Fax: +47 74 27 19 05
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4.7 Key project data Location: Mediå, the centre of Grong municipality, in the middle of Norway, about 65 degrees north Site and surroundings: Semi-urban with low-rise buildings. Flat Owner:
The municipality of Grong
Research project:
SINTEF and NTNU, Trondheim
Architect: HVAC engineer: Electrical engineer: Structural engineer:
Letnes Arkitektkontor A/S, Verdal PlanConsult VVS, Namsos Ryjord AS Nord, Steinkjer Planstyring AS, Steinkjer
Contractor: Construction work:
Tor Nykvist & Søn AS, Namsos Started in September 1997. Completed in August 1998
Cost – Total building: 14,0 million NOK Cost – HVAC: 1,5 million NOK Gross floor area: 1001 m2 Number of storeys: 1, plus distribution ducts in basement and attic Floor to ceiling height: 2.7 – 4.0 m (sloped roof) Personnel load:
200 pupils + teachers and staff
Outdoor climate:
Summer design temperature: 23°C. Winter design temperature -23°C Unsteady wind speed and directions, relatively long calm periods. Periods with dust and pollen from agriculture. Particles from oil and wood burning during winter.
Heating:
Hot water convectors. Hydronic coil ventilation air pre-heating Glycol run-around system that pre-heats ventilation air
Heat recovery:
4.8 References Lerum, Vidar, Matusiak, Barbara, and Thyholt, Marit. Daylighting Design for Grong Primary School. The SINTEF Group, 1998. STF22 A98509 Tjelflaat, Per Olaf, and Rødahl, Eystein.
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Design of Fan-Assisted Natural Ventilation. General Guidelines and Suggested Design for Energy-Efficient Climatization-System for Grong Primary School. The SINTEF Group, 1997. STF22 A97557
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Hökegård School, Sweden – refurbishment
Åke Blomsterberg, J&W and SP Åsa Wahlström, SP 5.1 Description of the project The school is located in Göteborg and was built in 1964 containing 11 classrooms, dining hall, kitchen, gymnasium, offices and with a total floor area of 2350 m². The school was a primary school with 350 pupils. Almost 50 % of the schools in Sweden were built during 1961 and 1975. It is the group schools with the highest use of energy i.e. 170 kWh/m2year for heating. The building has one storey and was built in a U-formation with an internal asphalt schoolyard. The building and the HVAC technology are rather typical for the period (see table 5.1 and table 5.2).
Figure 5.1 The Hökegård school after refurbishment.
Figure 5.2 Floor plan of the east wing of the Hökegård school. The east wing can be seen in the photo above as the part of building with chimneys. The east wing contains mainly classrooms, and to the left a kitchen and a dining hall.
Table 5.1 Building construction before refurbishment, Hökegård school.
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Building component Construction Roof Windows Exterior walls Interior walls
U-value, W/m²K Flat with12.5 cm mineral wool 0.35 Large double pane 3.1 Bricks + 5 cm mineral wool 0.45 Bricks
Table 5.2 HVAC system before refurbishment, Hökegård school.
Item Heating system
Characteristics Remarks Conventional radiators with thermostatic valves Energy for space District heating and hot water heating Ventilation system Mechanical Estimated specific use of exhaust and supply electricity of is 3 kW/m³/s. ventilation without Operating times is controlled heat recovery by a timer set on start 7.00 and stop 17.00. The ventilation rate is 6 l/(s and person) in classrooms with a total ventilation rate for the whole building of appr. 9000 m³/h. The indoor temperature in winter was appr. +22 °C. The installed artificial lighting was approximately 20 W/m². The yearly use of district heating was 500 MWh (210 kWh/m²) and the use of electricity was 60 MWh. As part of the refurbishment a new 100 m2 passage between the existing east and north wings has been built and the asphalted schoolyard has become a garden with an outdoor place. Shear exterior and interior walls of untreated bricks have been considered as a resource for the indoor comfort since they have good heat capacity and and have therefore not been changed. The overall aim of the Swedish project is to demonstrate energy efficient and ecological schools with a healthy indoor climate. Modern building technology, heating and ventilation technology will be combined with natural materials, natural ventilation and passive heating and cooling. Most cities will in the near future build new schools and refurbish old schools to meet the expected gradual increase in number of pupils within the next ten years. Schools have been or are being or will be refurbished, mainly to improve upon the indoor environment. It is therefore an excellent opportunity to demonstrate that this can be done in an energy efficient way and at the same time improve the indoor environment.
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The aim is based on a total energy optimisation to reduce the yearly use of district heating for the refurbished school for space and hot water heating by 50 %, and at the same time obtain a 40 % saving of total electricity and specifically a 50 % saving of electricity for lighting and a 70 % saving of electricity for ventilation - compared with the situation before renovation. The refurbished school is mainly heated by district heating generated by a sewage water heat pump, wood-fired plant and garbage burning with low emissions. There is also a small biomass heating plant. If the refurbished school had had oil based heating system, then the reduction in CO2 emissions would have been 50 %. 5.2 The energy saving concept and the technologies The overall energy saving concept was to create an energy efficient educational building by combining modern building, heating and ventilation technology with natural materials, natural ventilation and passive heating and cooling. At an early stage detailed performance specifications were developed covering ventilation, thermal comfort, sound, lighting and energy use. The innovative energy retrofits have been the following: - additional thermal insulation of the roof (1/3 of the building, the east wing) - low energy windows with a U-value of 1 W/m²K (1/3 of the building, the east wing) - advanced energy mangement system incl. advanced control system for heating and ventilation (the west, north and east wings) - improved daylighting (clerestories with reflectors and parabols on 1/3 of the building, the east wing) - hybrid ventilation (1/3 of the building, the east wing), combining passive stack and mechanical exhaust ventilation (see figure 5.3 and 5.4) - energy efficient ventilation i.e. balanced mechanical ventilation (use of electricity 1 kW/m³/s) with heat recovery (the west and north wings) - energy efficient ligthing devices (installed electric power in classrooms 13 W/m², in corridors 8 W/m²) - artificial ligthing controlled by presence detectors i.e. switching off the ligths - energy efficient appliances (copy machines etc) - night cooling, not yet being used - passive solar energy (appropriate sun shading) - application of new directives for procurement of energy efficient equipment
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Reflecting surface
Duct from rest room Clerestory
Concrete duct
Open able window
Control GX (ppm CO2) GT (qC) Push button
Supply grill Radiator
Heat-coil
Crawl space
Figure 5.3 The principle of the hybrid ventilation system in the east wing of the Hökegård school.
Figure 5.4 The Hökegård school after refurbishment with ventilation chimneys incorporating skylights.
All the new materials (paint etc) being used for renovation are healthy materials i. e. low emitting materials. 5.3 Energy savings and reduced emissions The monitoring period was started with one time tests to discover if the installed heating and ventilation system was functioning as designed and to determine certain value (air flows in mechanical ventilation system, air flow in hybrid ventilation system, thermal comfort, sound pressure levels, daylight levels etc). The actual monitoring phase, lasting two years, included continuous measurements of outdoor environment, indoor environment, energy use and system operation. The monitoring system was integrated with the building energy management system (BEMS). A detailed performance specification was developed for the BEMS.
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After refurbishment the use of the school was changed from a traditional school to a school for physically handicapped pupils and with caretaker, teachers and other personell totally 70 pepole will be using the school. The school is mostly used during the school year, which means 185 weekdays between 8 and 15 o’clock and mainly closed during the summer. The yearly space heating load (kWh/m²) was corrected to a reference year, the heating season 1971 of Stockholm. The internal gains from persons was corrected to be the same value for the energy analysis before and after retrofit. The total internal gains are for before 16 kWh/m²year, prediction after 13 kWh/m²year, actual after 8 kWh/m²year. The internal gains from persons before retrofit was corrected to be according to the new use (much fewer persons) of the building after retrofit. Below the energy use is shown. Table 5.3 Normalized (for climate and much fewer persons) energy use for space heating, kWh/m2year, Hökegård school, reference climate Stockholm 1971.
Before1 Predicted for refurbish refurbishment -ment
for after Actual1 refurbishment
after Conventional new building
North and East wing North and East wing, new west wing with west wing, hybrid hybrid partly new ventilatio mechanica ventilation l , improved n ventilation thermal insulation 240 144 124 175 108 125 1 Calculated values, where the calculation model agrees with monitored values. Below the annual use of electricity is presented. Table 5.4 Annual use of electricity1 (kWh/m²), Hökegård school, for: 1998.
Ventilation Lighting Operation
Before Predicted for Actual for a new Conve refurb- after construction/after ntional ishment2 refurbishment refurbishment2 new building North East North East and wing and wing west (hybrid west (hybrid wing ventilat wing ventilati ion) on) 15 5 2 13 2 10 15 8 8 4 4 15 6 6 6 3 3 5
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Total 36 19 16 20 9 30 1 all values corrected to be valid for the activity level of today after refurbishment i.e. operating times and internal gains 2 Estimated from measurements of total electricity The actual energy use for space heating after retrofit is somewhat different from the predicted energy use. The actual space heating load for the north and west wings is however higher than the predicted one due to lower actual average air-to-air heat recovery efficiency e.g. one major fan has no neat recovery. The actual space-heating load for the east wing with hybrid ventilation is lower than the predicted one due to lower airflows than expected. The electricity use of fans in the north and west wings is higher than predicted. This is due to the difficulties in arriving at a low SFP-value (specific fan power) in an existing building e.g. most of the ductwork and the old small fan rooms are the same. A ventilation system with low pressure drops requires more space than is usually available in an existing building. The east wing with hybrid ventilation has a lower energy use for space heating than the north and west wing thanks to increased roof insulation and new energy efficient windows, and a lower ventilation rate. The east wing and the north and west wings are not fully comparable. The north and west wings contain offices, kitchen and dining hall, which is not the case for the east wing with mainly classrooms. The overall energy use for space heating of the school has been reduced by 35 %. For the west and north wings (new mechanical ventilation and some of the other retrofits) the reduction was 25 % and for the east wing (hybrid ventilation and all the other retrofits) 55 %. The overall use of electricity has been reduced by 35 %. For building NW the reduction was 45 % and for building E 75 %. 5.4 Evaluation of indoor environment The thermal comfort, the sound levels, the lighting and the indoor air quality fulfil the Swedish MEDUCA requirements, which are more stringent than the Swedish national requirements. The supply air temperature to the classrooms in East wing has been steady, even during very cold winter days. The air temperature in the occupied zones of the classrooms has remained close to 20 °C during the winter, with only minor deviations. The indoor temperature during the summers has been around 21 °C. Detailed measurements of thermal comfort have been done in two classrooms in the east wing during one week in February (average outdoor temperature of + 5.5 °C, small craft sothwest wind). The operative temperature differed less than 1 °C from the air temperature and the radiant temperature asymmetry was less than 3 °C except at one point at 0,1 meters height
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beside a window. The air velocity was less than 0.15 m/s and the relative humidity was between 35 and 40 %. Complaints were received from staff about noise from sources outside the building as soon as the system was started up. This was because noise, mainly from trams, but also from other road vehicles, was carried in through the ventilation chimney. The problem was dealt with by fitting acoustic dampers filled with mineral wool beneath the inlets to the chimney. Detailed measurements of noise in the east wing’s classrooms show that the noise level is acceptable in the occupant area but close to the recommended limit directly under the exhaust fan. When the fan is not working the wind may cause the same noise level. The clerestories make a real improvement of the daylight in the classrooms, especially in areas at a distance from the ordinary windows. Measurements have also showed that the reflectors in front of the clerestories make an important contribution to the daylight. Active tracer gas measurements have been made in the east wing, which shows the amount of outdoor-air that is supplied to each room. The results are that the fresh air ventilation performance in the classrooms was good while the fresh air supply to the smaller connecting rooms (restrooms and stores) was inadequate. Also passive tracer gas measurements have been performed during one month (December 1998). They show that the fresh air supply is considerable larger in the corridors then in the classrooms. One third of the air supply to the classrooms and other rooms are supplied from the corridor. Other experiences have proved that, at certain wind conditions, the airflow through the exhaust duct in the restrooms can change direction, so that cold air is blown into the restroom. The contaminated air will then continue into the classrooms and be evacuated through the chimney. Another observation is that it is very important that the fire door, in the passage that separates the west and the east wing, is closed so that the hybrid ventilation system can work without influence from the mechanical ventilation system. The staff is satisfied with the indoor environment in the east wing’s classrooms. The air in the rooms feels fresh when the days start and normally the windows are opened for cross ventilation once a day. Air temperatures are regarded as uniform and the clerestories are experienced as a true benefit. Some members of the staff work in both the east wing with hybrid ventilation and in the west wing with conventional mechanical ventilation. Most of them prefer the indoor climate in the east wing. 5.5 Cost benefits The total building costs (manufacturing and installation) for the refurbishment of Hökegård school are 16 200 000 SEK (1800 kEuro), out which 4 300 000 SEK (478 kEuro) is for the east wing and 8 900 000 SEK (989 kEuro) for the north and west wings. The costs of the
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retrofit measures influencing the energy use and the indoor climate are for the east wing 2 700 000 SEK (300 kEuro) (see breakdown in table below). If the combined energy saving measures only are considered then the payback time would be 40 years, assuming the price of electricty to be 1.00 SEK/kWh (0.11 Euro/kWh) and district heating 0.50 SEK/kWh (0.06 kEuro/kWh). As this is a retrofit situation, in most cases many of the measures would have been carried out due to wear and tear. The windows, the roof, the ventilation system and the artificial lighting very often have to be renovated in schools like the Hökegård school. This means that the marginal cost compared with a renovation to the original standard of the building should be considered i.e. how much more expensive are e.g. low energy windows compared with traditional windows. The payback time is likely to be much shorter in this perspective. Many of the measures also improve the indoor climate, which is difficult to price. Table 5.5 Building costs (manufacturing and installation) for the east wing of the Hökegård school, price level of 1997.
Measure New low energy windows Additional roof insulation Solar shading (venetian blinds) Daylight reflectors on walls Daylight reflectors on the roof BEMS Control system Hybrid ventilation incl. lanterns Efficient lighting
Energy saving measures
Costs, SEK Cost, SEK/m2 of floor area 392000 554 586000 828 13000 18 53000 75 34000 48 204000 288 262000 370 1004000 1418 141000 199 Sum 2689000 3798 (422 kEuro) 2472000
For the north and west wings the costs of the retrofit measures influencing the energy use and the indoor climate are 1 450 000 SEK (see breakdown in table below). If only the combined energy saving measures are considered the payback time would be 20 years, assuming the price of electricty to be 1.00 SEK/kWh and district heating 0.50 SEK/kWh. As this is a retrofit situation, in most cases many of the measures would have been carried out due to wear and tear.
Table 5.6 Building costs (manufacturing and installation) for the north and west wings of the Hökegård school, price level of 1997.
Costs, SEK Cost, SEK/m2 of floor area New balanced ventilation with heat 740000 450 recovery New efficient lighting 267000 162 Measure
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456000 1463000
277 890
The east wing is not fully comparable with the west and north wings due different use. The east wing is smaller and contains mainly classrooms, while the west and north wings contains not only classrooms, but also offices, kitchen, gym and dining hall. As to the classrooms there are implications that the indoor climate is better in the classrooms of the east wing, which is difficult to price. A fair comparison between the costs of a retrofit with hybrid ventilation and renewed and improved existing mechanical ventilation is not really possible for this school. The chosen system for hybrid ventilation does not only have an impact on the energy use, but does also improve daylight and lower the sound level from ventilation compared with the improved mechanical ventilation system. The hybrid ventilation system might also have lower maintenance costs. 5.6 Conclusions and lessons learned The overall reduction in energy use for space heating is 35 % i.e. for the east, west and north wing combined. The east wing with new hybrid ventilation without heat recovery, improved roof insulation and new very energy efficient windows, is more energy efficient than the west and north wing with new mechanical ventilation (only partly heat recovery). However, the ventilation rates are often too low in many of the small rooms in the east wing and therefore the design concept needs to be improved. The restrooms need reinforcement of the ventilation with exhaust fans or improved passive stacks e.g. taller and insulated. The smaller room needs air supply ducts with lower pressure drops and another design. It is not to reccomend to have a part of a building with a hybrid ventilation system that is in directly contact with another part that have a conventional mechanical ventilation system. If the exhaust/supply ducts are placed in direct contact with a noisy sorrounding sound absorbers are needed. The hybrid ventilation system itself is quiet. In general the indoor climate is improved, especially in the wing with hybrid ventilation. Daylight improvments with clerestories are beneficial for the perception of the indoor environment. For a hybrid ventilation system including lanterns the costs of the clerestories (lanterns) have to be lowered e.g. by designing lanterns which can be prefabricated. The overall reduction in use of electricity is 35 % i.e. for the east, west and north wing combined. The electricity use of the renovated mechanical ventilation system in the north and west wings is however higher than predicted/expected. This is due to the difficulties in arriving at a low SFP-value (specific fan power) in an existing building e.g. most of the ductwork and the old small fan rooms are the same. A ventilation system with low pressure drops requires more space than is usually available in an existing building.
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The overall energy savings do not pay for the whole investment. However many of the energy saving measures are carried out due to wear and tear. Some of them improve the indoor climate, which is difficult to price. The energy savings can most likely pay for the marginal cost compared with a traditional refurbishment. The following conclusions can be drawn for the Hökegård school: 35 % reduction in energy use for space heating 35 % reduction in use of electricity improved indoor climate the hybrid ventilation system worked reasonably well but should be improvedthe hybrid ventilation system was quiet, but insufficient sound insulation to the outsideseparate rooms with hybrid ventilation from rooms with mechanical ventilationthe clerestories improved the daylight high cost of clerestories it was difficult to arrive at low SFP values in an existing buildingthe energy savings do not pay for the whole investment the energy savings can pay for the marginal cost compared with a traditional refurbishment Many of the above retrofits are applicable to many schools in Sweden, especially the ones built during the sixties and seventies. 5.7 Key project data Location: Suburb of Göteborg, 57 degrees north Site and surroundings: The immediate surroundings are hilly with some trees. At some distance there are apartment buildings with 3-4 storeys. On the east side, at a lower level, there is a main road and tram railway which connects the area with the city center. Owner: The city of Göteborg Research project: Swedish National Testing and Research Institute Architect: CNA Architects and EFEM Architects HVAC engineer: Anderson & Hultmark HVAC Consultants Electrical engineer: Skandiaconsult AB Structural engineer: VBK Contractor: Johansson & Rehn Byggnads AB Construction work: 1997, originally built in 1964 Cost – Refurbishment: 1.8 million Euro (manufacturing and installation) Gross floor area: 2350 m2 Number of storeys: 1
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Floor to ceiling height: 3.3 m Personnel load: 70 after refurbishment to a school for handicapped Outdoor climate: Winter design temperature -16°C. Coastal climate. 5.8 References Blomsterberg, Å., 1983, Energisparprogram Vilbergsskolan (program of energy savings). Swedish National Testing and Research Institute, report September 1983, Borås, Sweden. Blomsterberg, Å. Et al, 2000. Energisnåla och sunda skolor MEDUCA – ett EU-demonstrationsprojekt (Energy efficient and healthy schools – MEDUCA – an EC demonstration project). Journal of Swedish HVAC association Energi&Miljö, 1/2000. Blomsterberg, Å., Nielsen, J.-R., Ruud, S.. MEDUCA Demonstrationsskolor för integrerad energieffektiv teknik (Demonstration schools for integrated energy efficiency). SP (Swedish National Testing and Research Institute) Rapport 2002:02. Byggforskningsrådet, 1992, Bra innemiljö I skolan (Good indoor environment in the school). Swedish Council for Building Research, T26:1992, Stockholm, Sweden. Byggforskningsrådet, 1996, 17 sunda hus – goda exempel daghem och skolor (17 healthy buildings – good examples day care centers). Swedish Council for Building Research, T1:1996, Stockholm, Sweden. Hellberg, A., etc., 1996, Att se, höra och andas i skolor – en handbok om innemiljö (To see, hear and breathe in schools - A handbook on the indoor environment), report from the National Board of housing, building and planning and the National Swedish Board of Occupational Safety and Health, Sweden. NUTEK (Swedish National Board for Industrial and Technical Development), 1994, Bra inomhusklimat & lägre driftkostnader – ombyggnad av skolor (A good indoor climate & lower operating costs – refurbishment of schools). NUTEK, Stockholm, Sweden. NUTEK, 1994, Programkrav belysning I skolor (Requirements on lighting in schools). NUTEK, Stockholm, Sweden. NUTEK, 1995, Rustad för skolan (Ready for the school). NUTEK, Stockholm, Sweden. NUTEK, 1996, Mindre energi och mer komfort – in I minsta detalj (Less energy and more comfort – in every detail). NUTEK, Effektiv Nu, No 1 February 1996, Stockholm, Sweden.
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37
SCB, 1984, Energy statistics for buildings with premises in 1994, SCB Publication Services, Örebro, Sweden.
Egebjerg School
6
38
Tånga School, Sweden – refurbishment
6.1 Description of the project The school is located in the city of Falkenberg and was built in 1968 containing 20 classrooms, 10 workshops, dining hall, kitchen, gymnasium and offices with a total floor area of 9350 m². Almost 50 % of the schools in Sweden were built between 1960 and 1975. It is the group of schools with the highest use of energy i.e. 170 kWh/m2year for heating. The school consists of four buildings (A, B, C and D), all of them with two storeys. Building A contains a kitchen, a dining hall, offices etc., building B mainly classrooms, building C mainly workshops and building D a gymnasium.
Figure 6.1 The Tånga school after refurbishment.
The building and the HVAC technologies of the Tånga school are somewhat better than what is rather typical for the period 1960-75 (see table 6.1 and table 6.2). Table 6.1 Building construction before refurbishment, Tånga school.
Building component Roof
Windows
Exterior walls Interior walls
Construction
U-value, W/m²K
Flat with 25 cm mineral wool
0.15 (loose fill insulation was added in 1991) Some double pane, mostly 3.1 and 2.0 triple pane windows (installed in 1989) Bricks + 12 cm mineral wool 0.4 Bricks
Table 6.2 HVAC system before refurbishment, Tånga school.
Egebjerg School
Item Characteristics Heating system Conventional radiators with thermostatic valves Energy for District heating space and hot water heating Ventilation Mechanical exhaust and system supply ventilation without heat recovery in building B and C, in building A partly with heat recovery installed in 1993
39
Remarks
Estimated specific use of electricity of is 3 kW/m³/s. Operating times is controlled by a timer set on start 7.00 and stop 17.00. The ventilation rate is 6 l/(s and person) in classrooms
The indoor temperature in winter is approximately +21 °C. The installed artificial lighting level is approximately 20 W/m². The yearly use of district heating is 1300 MWh/year (140 kWh/m²) and of electricity 470 MWh/year. The overall aim of the Swedish project is to demonstrate energy efficient and ecological schools with a healthy indoor climate. Modern building technology, heating and ventilation technology will be combined with natural materials, natural ventilation and passive heating and cooling. Most cities will in the near future build new schools and refurbish old schools to meet the expected gradual increase in number of pupils within the next ten years. Schools have been or are being or will be refurbished, mainly to improve upon the indoor environment. It is therefore an excellent opportunity to demonstrate that this can be done in an energy efficient way and at the same time improve the indoor environment. The aim is based on a total energy optimisation to reduce the yearly use of district heating for the refurbished school for space and hot water heating by 50 %, and at the same time obtain a 40 % saving of total electricity and specifically a 50 % saving of electricity for lighting and a 70 % saving of electricity for ventilation - compared with the situation before renovation. The refurbished school is mainly heated by district heating generated by biomass. If the refurbished school had have an oil- based heating system, then the reduction in CO2 emissions would have been 50 %. After reconstruction the school will still have the same use i.e. a school for pupils grade 7 – 9. 6.2 The energy saving concept and the technologies The overall energy saving concept was to create an energy efficient educational building by combining modern building, heating and
Egebjerg School
40
ventilation technology with natural materials, natural ventilation and passive heating and cooling.
Figure 6.2 The Tånga school after refurbishment with fan and solar assisted passive stack ventilation chimneys.
Figure 6.3 Ventilation chimney of Tånga school
Egebjerg School
41
Figure 6.4 Plan of the first floor of one of the wings of building B. On the plan is shown the inlets and ducts of the hybrid ventilation system. Also shown is the balanced ventilation system for the restrooms. The floor contains three classrooms, three grouprooms and a meeting room.
At an early stage detailed performance specifications were developed covering ventilation, thermal comfort, sound, lighting and energy use. The innovative energy retrofits has been the following: - low energy windows with a U-value of 1 W/m²K (only one wing, building B) - improved daylighting (only one wing, building B) - advanced energy management system incl. advanced control system for heating and ventilation - hybrid ventilation (see figure 6.1 – 6.5), combining passive stack including a solar chimney with assistance of an exhaust fan (only building B) - energy efficient balanced mechanical ventilation (use of electricity 1 kW/m³/s) with heat recovery (only building A and C) - energy efficient lighting devices (installed electric power in classrooms 13 W/m², in corridors 8 W/m²) - artificial lighting controlled by presence detectors i.e. switching off the light - energy efficient appliances (copy machines etc) - night cooling, not yet used - passive solar energy (appropriate sun shading)
Egebjerg School
-
42
application of new directives for procurement of energy efficient equipment
RC-1
Tchimney Tout
RC-2
Troom CO2
Manual control
Figure 6.5 The principle of the hybrid ventilation system in the Tånga school.
All the new materials (paint etc) being used for renovation are healthy materials i. e. low emitting materials. 6.3 Energy savings and reduced emissions The monitoring period was started with one time tests to discover if the installed heating and ventilation system was functioning as designed and to determine certain value (air flows in mechanical ventilation system, air flow in hybrid ventilation system, thermal comfort, sound pressure levels, daylight levels etc). The actual monitoring phase, lasting 2 years, included continuous measurements of outdoor environment, indoor environment, energy use and system operation for one year. The monitoring system was integrated with the building energy management system (BEMS). A detailed performance specification was developed for the BEMS. The above measurements were complemented with a standard indoor climate questionnaire to find out how the users perceive the indoor climate, heating and ventilation system and how the building is used (e. g. Occupancy profiles). This was done before refurbishment and when the school had been used for one year.
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The school is mostly used during the school year, which means 185 weekdays between 8 and 15 o’clock and mainly closed during the summer. The actual energy use for space heating of the school (building A + B + C) after refurbishment is somewhat higher than predicted (expected), 114 kWh/m2year compared with 80 kWh/m2year. The explanation is found looking at the individual buildings. In building A additional heat recovery was never installed in the ventilation system. For building B the expectations should be met if the ventilation rates are lowered during nights and weekends. During the first year of operation the dampers of the hybrid ventilation system were fully open for ten minutes every hour during nights and weekends due to airing of building damp. For building C the expectations are even exceeded due to better efficiency than expected. Table 6.3 Normalized energy use for space heating for building A, B (new balanced heat recovery mechanical ventilation for the restrooms and hybrid ventilation for the rest of the building) and C (new balanced heat recovery mechanical ventilation) of the Tånga school, kWh/m2year, reference climate Göteborg 1988.
Before refurbishment1 A 294
B 85
Predicted for after Actual for after Conv. refurbishment2 refurbishment1 New bldg C A B C A B C 133 153 59 74 310 58 62 125 2 (90)
1
Calculated values, where the calculation model agrees with monitored values 2 58 will be achieved according to calculations, if the ventilation rates are lowered during nights and weekends.
The electricity use of fans are lowered in all buildings, but building A, where nothing was changed. For building B and C the expectations were exceeded thanks to a conservative prediction and better than expected performance. The prediction for the building B did not really take into account the potential of hybrid ventilation. The prediction was based on an energy efficient demand controlled mechanical ventilation system. The electricity use for lighting has been reduced to a level lower than the predictions. Table 6.4 Annual use of electricity (kWh/m²). Tånga school, for: 2000-2001
Before refurbishment1
Predicted for Actual for after Con after refurbishment v. refurbishment new bldg A B C A B C A B C Building 7 10 22 22 22 22 17 17 12 0.5 Ventilation 2 (10)
Egebjerg School
Lighting Operation Total
18 10 50
44
18 10 50
18 10 50
18 10 50
11 10 38
11 10 38
8 9 29
7 12 20 (29)
8 13 28
15 5 30
1
estimated from measurement of the total use of electricity for the whole school 2 0.5 represents the hybrid ventilation fans, 10 also includes the balanced heat recovery ventilation system for the restrooms and the fans for the fume cupboards.
Overall the energy use for space heating has been reduced by 20 %. For building B the reduction is 30 % and for building C 50 %. The two buildings are not completely comparable, as the area and the type of activity are different. Building B has primarily classrooms and building C workshops. The overall electricity use for ventilation has been reduced by 55 % and the overall electricity use for lighting by 45 %. 6.4 Evaluation of indoor environment The thermal comfort, the sound levels, the lighting and the indoor air quality fulfil the Swedish MEDUCA requirements, which are more stringent than the Swedish national requirements. The indoor temperature weekdays (6.00 – 18.00) varied during the period March 2000 to February 2001 (excl. June 15 – August 15 when the school is empty) between 20 and 24 °C in the six classrooms with hybrid ventilation, according to continuous detailed monitoring. Only a few days when the outdoor temperature was above 25 °C did the indoor temperature exceed 24 °C. The air temperature at floor level (measured at 0.1 meter height) has been above 19 °C except for a few days then the temperature was around 18 °C. The vertical temperature difference fulfilled the requirement of less than 3 °C during the complete period. Detailed measurements of thermal comfort were carried out in two classrooms with hybrid ventilation during a warm and sunny spring week (average outdoor temperature of 13.0 °C). The operative temperature differed less than 1.5 °C from the air temperature and the radiant temperature asymmetry was less than 3.5 °C close to the windows and close to the door less than 0.5 °C, which is below the requirements of 5 °C. The operative temperature is between 20 °C and 22.0 °C, but can be up to 24 °C for short periods (20-30 minutes) at points close to the windows. The air velocity was less than 0.10 m/s close to the windows and less than 0.06 m/s close to the doors. The air velocity was also below the requirement of 0.15 m/s during measurement done when the outside temperature was 4 °C. Measurements of sound in classrooms with hybrid ventilation show that the sound level caused by noise outside is acceptable except directly beside the air intakes that are facing the road, where 41 dB LpA was measured. The requirement on noise from HVAC was
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exceeded at 2 meters height in classrooms with balanced ventilated building (building C). However, most of the noise was due to other installations since nearly the same noise level was measured when the ventilation system was turned off. The lighting was measured both before and after refurbishment. The lighting requirements are fulfilled except for a few cases where the installed lighting power per square meter is slightly too high. The daylight level and quality is in one case slightly less than what is reasonable to require. The clerestories in the corridors make a real improvement of the daylight. Ventilation rates and indoor air quality have been measured in detail in six classrooms with hybrid ventilation, during the period March 2000 to February 2001. The CO2 concentration is mostly around 1000 ppm and only for short periods (10-20 minutes) higher, but very seldom above 1500 ppm. The relative humidity has been between 30 and 60% as required except at very cold days, below -6 °C, when the humidity has been 25%. The ventilation rates are higher in the classrooms on the first floor than on the ground floor. At fan assisted operation and fully opened dampers the ventilation flow reaches the design values of 210 litres per second and without fan assistance the ventilation flow can reach the design value of 132 litres per second. At times the airflows are quite low but on the other hand the CO2 concentrations are above 1000 ppm only for short periods. The particle concentration was measured during two days and as expected the concentration is nearly the same as the outside concentration since the air intakes has no filters. The concentration in the classroom that has air intakes close to the road is somewhat higher than in the classroom facing the yard. A questionnaire before and after refurbishment shows that the personnel perceived the indoor climate as rather good already before the refurbishment with regard to air and ventilation, heat and temperature, daylight and lighting, sound and noise, and cleaning and well-being. Thanks to the refurbishment the indoor climate was further improved. In general the indoor climate can be considered as approved if the frequencies of complaints for the answering alternative “often” is lower than 20 %. Before refurbishment 25 % of the pupils were often troubled by stuffy air and after 16 %. Before refurbishment 28 % perceived that it is was cold mornings, which now had been improved. After refurbishment draft from air supply has become a problem, 23 % of the pupils and the personnel after refurbishment compared with 2 % before refurbishment, often perceive troubles. Cold and sunny winter days, problems with draft can occur from the air supply devices, when the dampers are fully open due to full classrooms.
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Both pupils and teachers perceive daylight and lighting as good (very good according to 28 % of the students) already before the refurbishment, but perceive that it is even better (very good according to 45 % of the pupils) after refurbishment. Both pupils and teachers perceive the sound level before and after refurbishment as fairly good. The number of pupils often troubled by sound from ventilation has however increased from one to five percent, which anyway is a very low frequency of complaints. For classrooms with air intakes towards the road the reason can be noise from trucks passing by. However, there are only one or two trucks passing each day and this can be taken care of with sound insulation of the air intakes. The air intakes are not equipped with any special silencer. To improve the sound attenuation should not be difficult. The personnel appreciate that the hybrid ventilation system can be operated manually and they do so fairly often. Active tracer gas measurements have been made during one week in February 2000 in the hybrid ventilated building, which shows the amount of outdoor air that is supplied to each room. The result was that the ventilation rate was low but on the other hand the building was at that time not yet properly operated. However, the measurements showed that the continuously monitored ventilation flow in the exhaust duct represents the ventilation in the classroom very well. 6.5 Cost benefits The total building costs (manufacturing and installation) for the refurbishment of Tånga school are 23 000 000 SEK (2 556 kEuro), out which the costs of the retrofit measures influencing the energy use and the indoor climate is 2 350 000 SEK (260 kEuro) for building B (hybrid ventilation) and 875 000 SEK (95 kEuro) for building C (new energy efficient mechanical ventilation) (see breakdown in table below). If the combined energy saving measures only are considered then the payback time would be 17 years for building B, assuming the price of electricty to be 1.00 SEK/kWh (0.11 Euro/kWh) and district heating 0.50 SEK/kWh (0.06 Euro/kWh). As this is a retrofit situation, in most cases the installation of the new ventilation would have been carried out due to wear and tear. This means that the marginal cost compared with a renovation to the original standard of the building should be considered i.e. how much more expensive are e.g. a new hybrid ventilation system compared with a traditional mechanical ventilation system without heat recovery. The payback time is likely to be much shorter in this perspective. Many of the energy saving measures also improve the indoor climate, which is difficult to price. Table 6.5 Building cost (manufacturing and installation) for the Tånga school, price level of 2000.
Egebjerg School
Measure
47
Description
Costs, SEK Total, SEK/m2 Low energy Exchange of old 149000 windows, building windows in one wing B (1/4 of the floor area of building B) BMS Additional cost for 672000 807 (90 Euro) hybrid ventilation total hybrid ventilation system Hybrid ventilation, Three solar chimneys 624000 building B Hybrid ventilation, Duct system etc. 722741 building B Energy efficient Exchange of old 137158 balanced system ventilation, building B Energy efficient Exchange of old 862000 787 (87 Euro) balanced system ventilation, building C Lighting Additional cost for 50000 energy efficient lighting Solar shading, Additional cost for 10500 building B shading devices 3227399 For building C the costs of the retrofit measures i.e. the new ventilation system and additional costs for energy efficient lighting, influencing the energy use and the indoor climate is 875 000 SEK (97 kEuro) (see breakdown in table above). The payback time for these two measures combined would be 13 years, assuming the price of electricty to be 1.00 SEK/kWh (0.11 Euro/kWh) and district heating 0.50 SEK/kWh (0.06 Euro/kWh). As this is a retrofit situation, in most cases the measures would have been carried out due to wear and tear. Building C is not fully comparable with building B due to different floor areas and different use. The B building contains mainly classrooms, while the C building contains mainly workshops. As to the classrooms there are implications that the indoor climate is better in the classrooms of the B building, which is difficult to price. A comparison between the costs of a retrofit with a demand controlled hybrid ventilation and renewed and improved existing mechanical ventilation controlled by a timer for this school, can only result in orders of magnitude. The chosen system for hybrid ventilation does not only have an impact on the energy use, but does also lower the
Egebjerg School
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sound level from ventilation compared with the new improved mechanical ventilation system. The hybrid ventilation system might also have lower maintenance costs. The savings in energy use for space heating thanks to the demand and time controlled hybrid ventilation system and the time controlled mechanical ventilation systems with heat recovery are of the same order of magnitude in the Tånga school and so are the investment costs. The reference for the energy savings is a conventional balanced mechanical ventilation system without heat recovery. The advantage of the hybrid ventilation system is that it is demand and user controlled, that the use of electrity is very low and that the sound level from ventilation is lower, it is basically quiet. However sound from outside the building can be a problem. 6.6 Overall conclusions/lessons learned (design concept) The overall reduction in energy use for space heating is 20 % i.e. for building A, B and C combined. For building B (with new demand controlled hybrid ventilation) the savings is 30% and for building C (with new time controlled mechanical ventilation) 50%. The energy use for space heating of a building like Tånga school can be of the same order of magnitude for demand and time controlled hybrid ventilation and time controlled mechanical ventilation with heat recovery. The use of electricity for ventilation will be lower with hybrid ventilation and so will the sound level from ventilation. The sound level from outside was however higher in the Tånga school and should preferably be lowered by designing and installing sound absorbers in the outdoor air vents of the hybrid ventilation system. The control system should be reprogrammed e.g. by including a timer on the manual control of the hybrid ventilation. Other improvements would be to raise the ventilation rates of the ground floor to the level of the rates of the first floor. The possibility to manually operate the hybrid ventilation was appreciated by the staff. The building with hybrid ventilation has also a balanced mechanical ventilation with heat recovery for the restrooms operating continuously. This system should be replaced with a simple exhaust fan system controlled by a timer and thereby further reducing the use of electricity. The overall reduction in use of electricity for ventilation is 55 % and the overall reduction in use of electricity for lighting 45 %. The reduction in use of electricity for ventilation in building B was 55 % (but could be 95 %) and in building C 70 %. The indoor climate was improved. However, better coupling between the control of the convectors and the temperature of the outdoor air entering the classroom, would be desirable. At times there are problems with cold draught. At times it would probably make sense if the automatic control of the hybrid ventilation was not influenced only by CO2 content in the classroom, but also by the air temperature of the classroom.
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The overall energy savings do not pay for the whole investment. However the renewal of the ventilation system is mostly due to wear and tear and the indoor climate is improved, which is difficult to price. The energy savings can most likely pay for the marginal cost compared with a traditional refurbishment. The following conclusions can be drawn for the Tånga school: 20 % reduction in energy use for space heating (building B: 30% and building C: 50%) 55 % reduction in use of electricity for ventilation 45 % reduction in use of electricity for lighting improved indoor climate some improvements of the control of the hybrid ventilation system recommendedbetter co-ordination between control of room and air supply temperature (bluilding B) use of electricity for ventilation could be much lower (building B)the hybrid ventilation was quiet, but insufficient sound insulation to the outside the manual operation of hybrid ventilation appreciated the energy savings do not pay for the whole investment the energy savings can pay for the marginal cost compared with a traditional refurbishment Many of the above retrofits are applicable to many schools in Sweden, especially the ones built during the sixties and seventies. 6.7 Key project data Location: City of Falkenberg, 56 degrees north Site and surroundings: The school is located in a mostly residential area. The immediate surroundings are flat with some scattered trees to the south. At some distance there are some residential buildings. Owner: The city of Falkenberg Research project: Swedish National Testing and Research Institute Architect: CNA Architects and EFEM Architects HVAC engineer: Steninge Ventilation AB Electrical engineer: Scandiaconsult Elteknik AB Structural engineer: SF Byggkonsult Contractor: Förenade Bygg AB Construction work: 1999-2000, originally built in 1968 Cost – Refurbishment: 2.3 million Euro (manufacturing and install-ation)
Egebjerg School
Gross floor area: Number of storeys: Floor to ceiling height: Personnel load: Outdoor climate:
50
9350 m2 2 3.3 m 450 pupils + staff Winter design temperature -16°C. Coastal climate.
6.8 References Blomsterberg, Å., 1983, Energisparprogram Vilbergsskolan (program of energy savings). Swedish National Testing and Research Institute, report September 1983, Borås, Sweden. Blomsterberg, Å. Et al, 2000. Energisnåla och sunda skolor MEDUCA – ett EU-demonstrationsprojekt (Energy efficient and healthy schools – MEDUCA – an EC demonstration project). Journal of Swedish HVAC association Energi&Miljö, 1/2000. Blomsterberg, Å., Holmberg, Stina, ”Sundare skolmiljö” (healthier school environment) environmental section of Sydsvenska Dagbladet (daily issue 140 000) February 5, 2002. Blomsterberg, Å., Nielsen, J.-R., Ruud, S.. MEDUCA Demonstrationsskolor för integrerad energieffektiv teknik (Demonstration schools for integrated energy efficiency). SP (Swedish National Testing and Research Institute) Rapport 2002:02. Byggforskningsrådet, 1992, Bra innemiljö I skolan (Good indoor environment in the school). Swedish Council for Building Research, T26:1992, Stockholm, Sweden. Byggforskningsrådet, 1996, 17 sunda hus – goda exempel daghem och skolor (17 healthy buildings – good examples day care centers). Swedish Council for Building Research, T1:1996, Stockholm, Sweden. Ericsson, J., Wahlström, Å., “Use of multi-zone air exchange simulation to evaluate a hybrid ventilation system” Submitted to ASHRAE 2002 Annual Meeting, June 22-26 2002, Honolulu. Hellberg, A., etc., 1996, Att se, höra och andas i skolor – en handbok om innemiljö (To see, hear and breathe in schools - A handbook on the indoor environment), report from the National Board of housing, building and planning and the National Swedish Board of Occupational Safety and Health, Sweden. NUTEK (Swedish National Board for Industrial and Technical Development), 1994, Bra inomhusklimat & lägre driftkostnader – ombyggnad av skolor (A good indoor climate & lower operating costs – refurbishment of schools). NUTEK, Stockholm, Sweden.
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NUTEK, 1994, Programkrav belysning I skolor (Requirements on lighting in schools). NUTEK, Stockholm, Sweden. NUTEK, 1995, Rustad för skolan (Ready for the school). NUTEK, Stockholm, Sweden. NUTEK, 1996, Mindre energi och mer komfort – in I minsta detalj (Less energy and more comfort – in every detail). NUTEK, Effektiv Nu, No 1 February 1996, Stockholm, Sweden. SCB, 1984, Energy statistics for buildings with premises in 1994, SCB Publication Services, Örebro, Sweden. Wahlström, Å., Nielsen, J.R., “Hybrid Ventilation Retrofit in a School Setting” proceeding of the conference Performance of Exterior Envelopes of Whole Buildings VIII, Orlando, USA, December 2-7, 2001. Wahlström, Å, “Enkätundersökning om inomhusklimat före och efter ombyggnad av Tångaskolan” (Questionnaire survey on the indoor climate before and after the refurbishment of the Tånga school), SP AR Rapport 2001: 40, Energiteknik, Borås 2001
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Egebjerg School
7
53
Egebjerg School, Denmark
by Ove Mørck, Cenergia Energy Consultants
Fig. 7.1 Egebjerg School
7.1 Description of the project Ballerup is located 15 km West of Copenhagen. The area is an active area with more work-places than active workers. The school was intended to become the geographical and cultural centre of a housing area, which was planned to be build at a former brickyard. But it started on open land surrounded by cattle and horses. In the year of 1996, when an international housing-exhibition was held on Egebjerggaard, the completion of the area was ended and the school could capture its intended, central part. The surrounding buildings are mainly dwellings and a few shops. Architecturally the school was sketched over the structural building principle in a late modernistic style. The example for the house was Freies Universität in Berlin and Odense University in Denmark. The expression is strongly influenced by Japanese building traditions. Common educational facilities are situated in flexible, general building sections for the different age groups of pupils. The house is built over an open post-and-beam construction made of steel, closed by light, self-supporting walls made of wood, gypsum plates, glass and eternite-plates. The house is erected over a main module of 7,8 m. x 7,8 m. The roof is quite flat and made as a built-up construction on concrete plates.
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The interior and the sectioning were meant to be changed quickly and simple to be adjusted to new demands. Special rooms are placed in building sections specially formed for the purpose. The school has been planned after the educational principle building on open plan teaching. There is open connection between the classrooms and the two story high common space in the middle of each educational section.
Fig. 7.2 Floor plan of Egebjerg school. The characteristic, simple and almost uniformed architecture with straight lines and regular building dividings calls for very exact solutions of the projected improvements. The contemplated rebuilding of the school in stages implied that old and new had to live together and this strengthened the demands and bindings of the expression.
Egebjerg School
7.2
55
The energy saving concept and the technologies
7.2.1 Construction Additional thermal insulation of the building envelope: primarily the roof: Moderate erection of the roof made by building in extra insulation material in the construction, extended gutters, daylight lanterns and the large ventilation chimneys needed to be very simple and forceful elaborated. They could not distort the architecture, but had to accentuate and underline it. The high and forceful ventilation chimneys should send out a signal of innovation and new thinking. A completely new roof construction with a sloped roof is replacing the original flat roof. An additional average of 20 cm of mineral wool is added, reaching a 30 cm thick insulation level. All facades will be completely renewed. The new insulation thickness is 20 cm of mineral wool. All windows in the selected sections of the school was replaced by new low-energy windows with a U-value of 1.7 W/m²K. 7.2.2
Solar heating systems - passive/active
Day-/artificial lighting New daylight lanterns to allow light from the south and sky-light into the class rooms were designed and installed in stead of simple plastic “lids”. The new lanterns can also provide additional natural ventilation when needed by opening a window – driven by an electrical motor. he roof lights have a vertical part for direct sunlight (primarily turned towards the south) and a sloping part towards the sky for diffuse light.
Fig. 7.3 Old and new roof-lights at Egebjerg School.
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Solar gain control In the light shaft of the roof lights a special arrangement of a light diffusing grid prevents glare in the class rooms. 7.2.3 Ventilation A complete, new natural ventilation system has been designed. The openness of the school does, that the carrying out of a natural ventilation system with outlet through new ventilation towers placed above the high common spaces is relatively simple to install.
Fig. 7.4 Section
The building is erected over a crawl space, and therefore the principle of supply with fresh air preheated by the earth ducts could fairly easily be built into the project, see fig. 7.4. Fresh air is taken in trough air ducts to a crawl space below the class rooms. From the crawl space the air is led into each class room behind convector radiators which have been designed to further preheat the air. Air is leaving the class room through corridors to the double height common assembly room, at the roof of which a combined stack effect, wind and solar chimney is placed. The chimney is designed to work by a combination of wind pressure and ordinary stack effect. Two separate chambers are heated as solar air collectors and are opened when the temperature rise so high that a considerable driving force is established. This feature is primarily designed for summer operation. A fan is located in the crawl space to generate a slight overpressure in case the natural driving forces are to weak to generate the necessary ventilation.
57
Fig. 7.5 Floor plan of one of the retrofitted sections of the school.
Fig. 7.6 Air inlet “swan-necks”
A solar air collector of the so-called “Canadian Solar Wall” is installed on the south facade of the double-height building. From the collector air is taken into the crawl space in stead of the air from the earth ducts, whenever it is the preheated to a higher temperature.
58
Fig. 7.7 Exhaust air tower with solar chimney
Fig. 7.8 “Canadian Solar Wall” air solar collector
7.2.4 Building energy mangagement system (EMS) An advanced EMS system was designed to not only control heating and lighting, but also the natural ventilation system. This includes
59
opening of windows at the solar chimney (see below) in the leeward side of the wind and opening of fresh air intakes according to temperature and CO2 levels. The EMS system is also used for the monitoring of the building. Air temperature and CO2 sensors are located in each class room and temperatures and air flows are measured at the fresh air intakes. Also energy meters in the retrofitted part and the equally sized part used for reference measurements are automatically read by the EMS system. 7.3 Energy savings and reduced emissions The Building Energy Management System has been used for the monitoring. The monitoring period wa: October 1998 to March 2001 The measures parameters appear from the table 7.1. Table 7.1 Measured data by the BEMS system
Measured data per section (2 No. of sensors sections) x2 Heat meter 2 Room temperature 7 CO2 7 Solar radiation 1 Outside temp. 1 Wind 1 Air flow (supply) 1 Temp in solar wall 1 Temperature in basement 5 Temperature in solar chimney 2
Frequency of data reporting daily hourly hourly hourly hourly hourly hourly hourly hourly hourly
The monitored data has been evaluated and results are presented in the daylighting and ventilation themeatic report of the MEDUCA project. As an illustration of some of the evalautions made are below two plots of the room temperature distribution – when occupied. Room Temperature 25.00
Distribution, %
20.00
15.00
10.00
5.00
18 .0 18 .3 18 .5 18 .8 19 .0 19 .3 19 .5 19 .8 20 .0 20 .3 20 .5 20 .8 21 .0 21 .3 21 .5 21 .8 22 .0 22 .3 22 .5 22 .8 23 .0
0.00
Temperature
Fig. 7.9 Average summer day
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Room Temperature 80.00 70.00
Distribution, %
60.00 50.00 40.00 30.00 20.00 10.00
.0
.8
23
.5
22
.3
22
.0
22
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22
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21
.3
21
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20
.5
19
.3
19
.0
19
.8
19
.5
18
.3
18
18
18
.0
0.00
Temperature
Fig. 7.10 Average winter day Table 7.2 Monthly space heating loads (kWh/m²) for 1999 corrected to a reference year for 1 part of the Egebjerg school school – 867 m²
Month January February March April May June July August September October November December Year Pr. m²
Before refur- Predicted after Actual after bishment refurbishment refurbishment 28888 14712 13800 24812 12636 14227 22560 11489 11342 14289 7277 6075 5761 2934 2292 0 0 0 0 0 0 0 0 0 4000 2037 821 11563 5889 5603 19005 9679 9446 26049 13266 12064 156927 79919 75670 181 92,2 87,3
Table 7.3 Annual space heating (kWh/m²) for 1999 corrected to a reference year.
Before refurbishment 181
Predicted after Actual after Conventional refurbishment refurbishment new building 92,2 87,3 140
Table 7.4 Annual electricity load (kWh/m²).
Ventilation Lighting Total
7.3.1
Before rePredicted Actual after Conventiofurbishment after refur- refurbishnal new bishment ment building 26 13,5 17,5 8 3,5 4,5 36 18 22 30
Total savings and reduced emissions
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The total heating and electricity energy savings for the total area of the renovated parts of the school and the corresponding reduced emissions from respectively the local CHP district heating plant and common electricity productions have been calculated. The savings and estimated emission reductions appear from table 7.5 Table 7.5 Total yearly savings and reduced emissions
kWh/m²/year Before After Savings Area, m² Total, kWh/year Reduced emissions, ton CO2/year
Heating Electricity 181 36 87 22 94 14 1714 1714 160602 23996 25,7 22,7
From table 7.5 it appears that the MEDUCA project at the Egebjerg School results in reductions of CO2-emissions of 48,4 tons a year. 7.4
Evaluation of indoor environment
7.4.1 Qualitative evaluation of the indoor climate after the renovation After the renovation of the first part of the school, C2, but before the renovation of the second part to be renovated, C1 teachers and pupils who frequent the 2 parts of Egebjergskolen have answered a questionnaire study o the indoor climate. This means that the C1 part is used as the reference for the outcome of the renovation. The questionaire has been developed in Sweden and has 17 fields covering direct sensation of air, noise and light quality as well as qualitative aspects of the indoor climate, such as: irritation of nose and troat, headaches, tiredness, etc. Air quality A large part of the teachers and pupils rate the air quality to be very good or fairly good in the renovated section while the majority in the non-renovated part rate the air to be acceptable or rather poor, see fig. 7.11. The conclusion is that the air quality has significantly improved. % 60 50 40 C1
30
C2
20 10 0 very good
quite good
acceptable
poor
very poor
62
Fig. 7.11 Perception of air quality “before”-C1 and “after”-C2.
Light quality 15% mean that the light quality “after” is very good compared to approx. 2% in the “before” situation. There are also 15% more who find the light quality acceptable, corresponding to approx. 15% less who find it rather poor and 10% less who find it very poor. It should be borne in mind that the classrooms already had roof windows and relatively large window areas in the facade so the basis vas rather good daylight conditions. General issues A considerably higher percentage never feels discomfort from dry, damp, stuffy air or static electricity “after” the renovation than “before”. A total of 11 questions concern unpleasant symptoms relating to the indoor climate. The result of the study as to these questions show an obvious connection with the direct perception of the air quality as described above. As regards all questions, the percentage that never has itchy eyes, irritated nose, hoarseness, cough, etc. has increased considerably “after” compared to “before”. 7.5
Cost benefits
7.5.1 Payback and other benefits Total yearly savings and the corresponding energy prices appear from table 7.6. Total savings are 13475 Euro/year. Table 7.6 Energy and economical savings
Yearly values Heating Electricity Total. kWh 160602 23996 Euro/kWh 0,06 0,16 Savings, Euro 9636 3839
Euro
13475
The construction costs divided by the yearly savings results in a simple payback time, see table 7.7. Obviously this doesn’t account for increasing energy prices and second order value from reduced emissions. Table 7.7 Simple payback calculation
Currency Construction costs Yearly savings Payback time
1000 DKK 3756 100 37
Euro 504188 13475 37
From a strictly economic point of view the renovation measures does not pay off. However, improved comfort and air quality and the resulting improved learning capability of the pupils plus improved health of pupils and teachers cannot be priced. 7.6
Conclusions and lessons learned
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Two sections of the school - a total of 1714 m² have been extensively renovated. As a result of the renovation the indoor air quality, light and thermal comfort have increased and the energy consumption for heating, ventilation and lighting considerably decreased. The renovation project has also led to a greater consciousness of resources among the pupils. The rebuilding of the north-western section of the school for the pupils in 8., 9. and lo. Class ( 14 - 16 years old ) was carried out in cooperation with the school management, the teachers, the pupils- and the parents representatives. The school was functioning underway and there was only few shifts of affected classes. Heating energy consumption The heating energy consumption has been reduced to 87,3 kWh/m² compared to 181 kWh/m² before the renovation. it should be noted that the overall heating energy consumption of the school has gone down during the renovation period due to a fine-tuning of the heating system and other initiatives. A comparison is also made to this reduced overall consumption (145 kWh/m²). Heating energy savings due to the MEDUCA measures are thus between 40 and 52 %. Electricity energy consumption The electricity consumption has gone down from 36 kWh/m² (average for the whole school) to 22 kWh/m². This reduction is mainly due to electricity savings on the ventilation of the building going from a complete balanced air mechanical ventilation system to a natural ventilation system with fan support. 7.7 Key project data Location: Site and surroundings: Built: Owner: Research project: Architect: HVAC engineer: Electrical engineer: Structural engineer: Contractor: Construction work: Cost of refurbishment: Gross floor area: Number of storeys: Floor to ceiling height: Personnel load: Outdoor climate: 7.8
References
Ballerup, 15 km West of Copenhagen Semi-urban with low-rise buildings. Flat The school was built in stages from 1973-81. The municipality of Ballerup Cenergia Energy Consultants, Ballerup Frank Jakobsen, Municipality of Ballerup Cenergia Energy Consultants, Ballerup Torkil Laursen, Tåstrup Torkil Laursen, Tåstrup L.P. Larsen, Måløv 1997-1998 504188 € 1714 m² refurbished out of 17825 m² in total 1-2 2.6 – 5.2 m flat ceiling 250 pupils + teachers and staff Winter design temperature -18°C. Prevailing westerly winds. Periods with pollen.
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1. VVS – Danvak, No. 4, Marts 1999. ”Frisk luft på energirenoveret skole” (“Fresh air at energy–renovated school”), Ove Mørck & Ole Balslev, Cenergia Energy Consultants.
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University of Almeria
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THE WITTORF SCHOOL
by Gerd Sigel, Stadtwerke Neumünster & Ove Mørck, Cenergia Energy Consultants
8.1 Description of the project With a population of slightly more than 80.000 Neumünster is the fourth largest town in the Federal State of Schleswig-Holstein and one of four towns in that state not belonging to a district. Neumünster is therefor a territorial authority (Gebietskörperschaft), which can fulfil ist municipal duties entirely on ist own. The town´s geographical position between the North Sea and the Baltic Sea has always proved itself to be advantageous. The city has good road and rail connections. It is situated at a main traffic junction; the one between Hamburg, 60 km in the south, and the danish border, 80 km in the north. The Wittorf School is located in the south of the city. Wittorf is the name of the municipal area in the south of Neumünster. The immediat surrounding of the school is flat with some trees in the east. There are two streets as a boundary of the school-yard. The >>Lindenstraße<< in the south with 50 meters distance to the school building, a road that follows to the city center with sometimes busy traffic. The >>Kiefernweg<< in the west, a dead end road with not much traffic. In the north of the sportshall is a connected sports ground. In the east is a little school wood as a natural border. In the direct neighbourhood of the school is a residental district with 2- or 3 storeyed buildings and some small shops. The Wittorf School has been built in several stages. The old school building (1) is a historical building from 1906 with half timbering. The pavilion section (2) was build between 1954 and 1962 with very poor insulation. An extension building (3) was build in 1973 as functional building with better insulation values. There are two sports halls built in 1958 (4) and 1980 (5). Total floor area is: 5274 m².
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3
Handarbe i
Abs tell
Raum
Rau m P8
Raum P11
Rau m P7
Abs tell
Rau m P4
Le hre rzi Te ek
Rau m P3
HeW rre
Vo rbe rei Raum P10
5
Rau m P6
Rau m P2 DaW me
4
Ra um
Rau m P9
Phys ik / Chemie
Rau m P5
Rau m P1
Vorbere itung
Gerät e
2 Gerät e / Bälle
Vo rbe rei
Ko pie rra
W Abstellra u m
Se kre tar
1
Le hre rzi
Re kto
Fig. 8. 1 Floorplan of the school numbered for the different sections mentioned above.
The school has 480 pupils. Connected is a school – kindergarten for app. 30 children and 2 rooms where the kids can do their homework with help of teachers, parents or others. 8.2 The energy saving concept and the technologies The strategies adopted for improved energy efficiency of the school was: • improved use of daylight and efficient artificial lighting • improved insulation levels of walls, roofs and, windows and HVAC piping • solar hot water system • advanced building energy management system • replacement of old gas heating boiler with district heating 8.2.1 Improved use of daylight and efficient artificial lighting The pavilion has rather large windows in the classrooms towards south-east and clerestory windows to north-west. In the original and extension buildings the classroom windows are mostly towards southeast - some are facing north-east. The daylight levels are generally quite high, but has not been made proper use of before, as the artificial light were switched on and off manually. At the renovation of the school energy efficient artificial lighting and daylight sensors was installed. The advanced BEMS system now controls the artificial lighting system according to occupancy and to daylight levels – thereby minimising the use of electricity.
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Daylight depending artificial lighting with integrated light sensor
= level of natural lighting
Fig. 8.2 Illustration of daylighting levels from facade windows. In the pavilion class rooms the clerestory windows even out this distribution significantly.
8.2.2 Improved insulation levels of walls, roofs, windows and HVAC piping Poor insulation levels caused too high heat losses in the older part of the school – the original school building and the pavilion building. This was improved by installing low energy windows with an U-value < 1,3 W/m2K in the pavilion section and in a part of the old school building, by adding insulation in the roof of the pavilion building ( 20 cm mineral wool) and by installing a new insulated door to separate a non heated pavilion section (when not in use) from the heated area of the extension building. Existing door stoppers catching the doors in an open position causing unnecessary heat losses were dismantled.
Fig.8.3 Added roof insulation.
In the 3-storey extension building complete new windows with well insulated frames and low-energy glazing (U-value < 1.3 W/m²K) were installed. Figure 8.4 shows the location of the added insulation layers in the pavilion building.
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Throughout the school buildings the heating pipes in not heated areas were insulated. An example of this piping/installation insulation is shown on fig. 8.5. additional insulation with 20 cm mineral-wool
5 cm insulation slab (Heraklith)
Fig. 8.4 Location of additional insulation in pavilion building.
Fig.8.5 New piping insulation
8.2.3 Solar hot water system To save energy and to demonstrate to the students at the school the use of renewable energy a solar hot water system has been installed, see fig. 8.6.
Fig. 8.6 Solar hot water system
8.2.4 Advanced building energy management system The installed building management system controls the consumption of heating energy in dependence to the time table of each classroom individually. A new feature is the combination of control panels of heating, daylight depending lighting, solar facility, hot water, electricity and consumption measurement in one system. The system
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can communicate by telephone networks and can be controlled by a remote panel by the local energy supplier. The system monitors the use of energy, the temperatures, the relative humidity and the CO2 concentration inside the classrooms and the weather outside.
Fig. 8.7 Plot of the daily schedule of a class room by the BEMS
The Building Central forms the higher connecting level of the DDC Sub-stations. It presents the central workplace of the user for operating and the for facility management. From the building central higher functions or programs getting started. Simultaneously the building central provides the interface to the management system, to organise the connection to other real estates and for the connection to companies for maintenance. At the Central total energy consumption for space heating, hot water, electricity and the renewable energy (solar hot water) contribution can be found and shown for any chosen period. Daylight depending artificial lighting (time table depending turning off controlled by the EMS) and timetable depending heating has been programmed into the system as well as normal-, and summer- saving programs. The system assures that the heating automatically stops when a classroom is not in use, or the windows are open for ventilation. Figure 8.7 shows a typical day of a class room with heating controlled by the system. The system also facilitates displaying the schools floor plan or a specific system (as the solar system on fig. 8.8) on a PC with all actual data from the heating central and each single classroom, statistic of the radiator valves, solar gains for hot water preparation and information if any defect occurred.
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Fig. 8.8 PC screen overview of the heating system.
8.2.5 Replacement of old gas heating boiler with district heating connection Replacing the old, existing gas heating central by establishing a connection to the local district heating network was the last part of the complete energy conservation concept. 8.3
Energy savings and reduced emissions
8.3.1 Heating The overall heating energy consumption for room and hot water heating has been monitored in the first year after completion of the renovation (it is continuously monitored also in the future) and compared to the consumption before the retrofitting of the school. The histogram in figure 8.9 shows the monthly consumptions in 1999 compared to the average monthly consumptions of the years 19941998. Another comparison is presented in figure 8.10, which shows the monthly savings in 1999 calculated either with the average 19941998 or the year 1996 as the reference. It is clear from both figures that savings are substantial. The overall percentage savings are presented overleaf.
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Energy consumption for heating and hot water comparison 1999 to the average of 94 - 98 [kWh] 250.000
200.000
150.000
100.000
50.000
0 Jan
1999
Feb
Mrz
Apr
Mai
Jun
Jul
Average 9 Aug
Sep
Average 94 - 98
1999
Okt
Nov
Dez
Fig.8. 9 Heating energy use before and after renovation.
Savings in heating energy and hot water comparison 1999 to 1996 and to the average of 94 - 98 140.000
120.000
100.000
80.000 [kWh] 60.000
40.000
20.000
0 Jan
Feb
Mrz
Apr
Mai
Jun
savings to 1996
Jul
Aug
Sep
Okt
Nov
Dez
savings to average 94 - 98
Fig. 8.10 Heating energy savings over the year.
8.3.2 Solar heating contribution to the hot water load The heating energy use for hot water preparation and the output of the solar hot water system in continuously monitored. The results for 1999 is shown in figure 8.11. It appears that the solar heating system - as expected – has close to a 100 % coverage og the hot water load in the summer months, whereas the contribution in the winter months is very limited. Over the year the system contributes 28 % of the total hot water load.
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Hot water energy use at Wittorf School 1.800
1.600
1.400
1.200
1.000 [kWh] 800
600
400
200
0 Jan
Feb
Mrz
Apr
Mai
Jun Solar hot water
Jul
Aug
Sep
Okt
Nov
Dez
D itithti
Fig. 8.11 Energy consumption for hot water and solar contribution in 1999.
8.3.3 Overall heating energy savings The overall heating energy savings are shown the table 8.1. Table 8.1 Heating energy consumptions and savings due to the MEDUCA project
Year 1994 1995 1996 1997 1998 1999
kWh 1.215.551 1.330.488 1.250.768 1.052.239 925.060 602.908
%
100
Average 94 - 98 Savings 1999 to 1996 Savings 1999 to average
1.154.821 647.860 551.913
100 52 48
solar hot water hot water district heating Total hot water
3.208 8.199 11.407
28 72 100
It appears from table 8.1 that overall heating energy savings are in the range between 48% and 52% and that solar energy contribution to the hot water load was 28 % in 1999.
Table 8.2 Heating energy consumptions and savings due to the MEDUCA project Before Actual after Conventional
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refurbishment Heat provided by 0 renewable Heat provided by 237 auxiliary system
refurbishment 0,6
new building 0
114
100-150
8.3.4 Electricity savings The combined effect of the new efficient artificial lighting system and the increased daylight use through the improved control of the artificial light shows on the electricity bill. The overall electricity consumption in the first year after the retrofitting had been completed, 1999 has been compared to the average of the years 94-98 before on figure 8.12. These consumptions include not only the electricity use for the lighting but also all other electricity consumption on the school. Nevertheless both plots show a significant reductions in monthly (except June/July) and yearly electricity use on the school. It should be noted that the lighting level from the artificial lighting systems at the same time has been improved by an average of 26 % throughout the school. electricity consuptiom avarage compared with 1999
14.000
12.000
10.000
8.000
6.000
4.000
2.000
0 Jan
Feb
Mar
Apr
May
Jun
Jul
average 94 - 98
Aug
Sep
Oct
Nov
Dec
consumption 99
Fig. 8.12 Electricity consumption over the year before and after renovation.
The overall electricity savings appear from table 8.3. It appears that overall electricity consumption in 1999 was 32.6 % less that the consumption in 1996 – considered as a typical year of the most recent years before retrofitting the school. Table 8.3 Overall electricity savings Year
Kwh
University of Almeria
1999 1996 Savings Percentage
75
72.392 98.998 26.606 32,6%
Table 8.4Annual use of electricity (kWh/m²)
Before Actual after refurbishment refurbishment 18,8 13,7
Conventional new building 16
8.3.5 Reduced CO2-emissions The overall heating and electricity savings correspond to reduced emissions from respectively the district heating and electricity productions. The estimated reductions appear from table 8.5 Table 8.5 Reduced CO2-emissions
Savings/reduced emissions Heating Electricity Total
MWh/year
Ton CO2/year
602,9 26,6
154 21 175
8.4 Evaluation of the indoor environment Thermal comfort The view expressed by both teachers and pupils is that the temperatures are both stable and comfortable. This is also supported by the monitored data that shows very stable room temperatures. The BEMS systems is working satisfactorily in controlling night set-backs and returning to comfort temperatures during work hours. Lighting The new artificial lighting system and the control of it is working according to specifications and adequeate lighting levels are maintained throughout the working days – and evenings. Ventilation The ventilation of the classrooms in the Wittorf school is assured in the old-fashioned way by opening windows – mainly during breaks. This has been recognised as not adequate and considerations for improvement are underway. 8.5 Cost benefits Project costs: Electrical installations (Lighting, Bus-system)169.000 Windows 368.000 Added insulation in walls and roofs 153.000 Individual room control+BEMS 80.000 Heating system+District heating+Solar system 399.000 Total costs: 1.169.000
DM DM DM DM DM DM
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Project savings Heating: 600.000 kWh/year at 0,13 DM/kWh = 78.000 DM/year Electricity: 26.600 kWh/year at 0,35 DM/kWh = 9.310 DM/year Total savings: 87.310 DM/year Payback time: 1.169.000 DM/87.310 DM = 13.4 years. 8.6 Conclusions and lessons learned The renovation was completed in 1998. The overall project results are 50 % heating energy savings and 33 % savings on electricity. Specific installed power effect of artificial lighting Before renovation: 9,6 W/m2 After the renovation: 6,4 W/m2 Total installed power effect of artificial lighting Before renovation:: 31 kW After the renovation: 20,7 kW At the same time the lighting level has been improved by 26% and the lifetime of the installations extended by 100%. The energy saving measures and the solar heating system has worked as intended. The overall payback time of 13.4 years prove that the concept seen as a whole is viable and suitable for copying by other German schools. 8.7 Key project data Location: Neumünster, Northern part of Germany, 54 degrees north. Site and surroundings: Semi-urban with low-rise housing. Owner: Stadt Neumünster Demonstration project: Stadtwerke Neumünster, contact person: Gerd Sigel:
[email protected] Architect: Klaus Richter, Stadt Neumünster Construction work: Started in September 1997. Completed in August 1998 Cost – renovation: 0,6 million € Gross floor area: 5372 m2 Number of storeys: 1-3 Floor to ceiling height: 2.4 Personnel load: 200 pupils + teachers and staff Outdoor climate: Summer design temperature: 23°C. Winter design temperature -10°C.
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9
University of Almería, Spain
by M. Pérez (UALM), M.R. Heras (CIEMAT), M. J. Jiménez (CIEMAT), M.J. San Isidro CIEMAT), L. Zarzalejos (CIEMAT), V. Quashning (DLR), F.J. de Luis (CIEMAT/UALM)
9.1 Description of the project technical and architectural The Spanish participation in MEDUCA project has consisted of the refurbishment of an existing 350 m2 courtyard in a building at the University of Almería, a seashore location in South-Eastern Spain, 36.8 ºN latitude. The constructive design of the roof used to cover the original light court has served to transform an open space in a multipurpose room to hold conferences, meetings, lectures...and it includes some innovative features related to the conscious use of energy for the fulfillmet of the thermal, daylighting and electricity demands. The enhanced roof structure is based on the conventional sawtooth concept, and it consists, as result of the specific design, of two main zones: x
Passive roof zone (South side), including five parallel north slopes with vertical openings approximately South orientated including solar control elements..
x
Active roof zone (North side), consisting of a 5 m high solar chimney and an integrated 5 kWp grid connected photovoltaic plant.
The roof installation works finished in September 1999 and PV plant is operative since September 2000.
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The courtyard had a square shaped plan and, initially, it was designed to provide daylighting and ventilation to the building internal corridors and rooms, having no other specific use. Due to the need of free spaces to hold conferences, lectures and exhibitions, the Technical Services of the University of Almería designed a conventional sawtooth roof aimed to cover the previous open space and it was decided to fulfil air conditioning loads by conventional means. The participation in the THERMIE program has allowed to reconsider this initial idea and to include some energy conscious design concepts. Among then, the optimisation the sawtooth roof thermal and daylighting performance by adequate treatment of the solar gains, increasing the winter contributions to reduce thermal loads but also avoiding one of the more important problems in air conditioning in our environment, the over-heating of internal spaces below translucent roofs during summer months. Thus, a special design of the roof structure has been undertaken by settling a specific orientation strategy of the vertical openings and incorporating overhangs as seasonal solar regulation elements. In addition to this, it has been also incorporated to the roof design an integrated chimney to provoke natural fresh air movements during summer as well as in the adjacent building corridors to achieve an adequate air quality and to exhaust warm air, when requested. Finally, the chimney structure has allowed the integration of a PV plant, financed by a national program. The PV plant feeds internal electrical appliances and produces an energy surplus contributing to the reduction of the electricity consumption of the rest of the building. In order to preserve the constructive simplicity and to avoid the costs increase in regard to the conventional solution, all the new features have been adopted after to verify that they do not suppose a relevant change on the basic sawtooth constructive concept. Both the roof and the integrated PV plant are also used in educational activities as living examples of building energy conscious approach. Urban environment and integration Almería is one of the Spanish provinces with a faster socioeconomical development thanks to two activities related to the existing available high insolation levels, the intensive agriculture and the tourism. The city downtown is located in the centre of a bay facing to the South and, according the sociological trends, the province population is being moved from the inland zones to the coastal ones, being increased the constructive activities in the seashore strip. The University of Almería is also placed facing Mediterranean sea, 6 km far from downtown in a Eastern direction and 2 km far from the city Airport. The surrounding is a semi-rural zone, including
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greenhouses as well as some single-family houses. The closest urban nucleus is a 2000 people suburb of the city located 3 km to the North of the University Campus. The urban-planning for the development of the city is focused to the East, being expected that the University becomes urban zone during the first decade of 21st century. The building in which the original courtyard was located, was recently built and its architecture is the selected one by the regional government for all the new Universities in Andalucia. It belongs to a group of buildings where the educational and academic activities for non technical studies are concentrated (Teaching, Laws, History,...). The general characteristic of this buildings group is a modern fashioned and a prevailing sharp appearance. The University of Almería was created to contribute to the cultural and technological background for all the new province perspectives and to became a reference of the foreseen new housing area of the city. 9.2 9.2.1
The energy saving concept and the technologies Building
Construction The structure of the MEDUCA roof (total surface is approximately 355 m2) can be separated, as advanced, in two zones, a passive zone consisting of five parallel 35 º North slopes 20 m wide and 1.7 m high and South vertical openings including 1.5 m slope in line overhangs. The active zone is placed in the North roof side an it consists of a 5 m high solar chimney including a manual damper on the top. The South face of the solar chimney is 45 º sloped, allowing the integration of PV panels. Structure and material The roof structure is made in light materials to reduce mechanical loads and it was covered by 50 mm polyurethane panels. The light vertical openings are cellular plastic with a light transmissivity of 0.7 and able to support existing wind loads. Shape - form The section of the space corresponds modified sawtooth roof (Windows opening to the South + overhangs + solar chimney). The plant is very regular square shaped. 9.2.2
Systems
Solar gain control Overhangs in the South vertical openings have been designed to avoid non desirable direct zenithal solar gains during summer months. During winter, direct gains are allowed.
Ventilation
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The adopted ventilation strategy try to take the advantages of two natural indoor-outdoor air interchange mechanisms to achieve adequate indoor air quality and thermal comfort. The first one is to ease warm air exhaust by stack effect, in those situations where requested, by the installation of the North chimney and additional air openings in vertical windows (louver type) and the second ventilation mechanism is the renovation of indoor air by outdoor fresh air coming from the coast (100 m far from the building) transferred by the sealand breeze process. These mechanism are expected to occur without mechanical support. 9.3
Evaluation of performance (evaluation & monitoring )
9.3.1 Performance estimation The key design condition from a energetic point of view is the obtaining of acceptable thermal and daylighting conditions with a minimum use of energy. Energy consumption either for lighting and for heating and cooling regard to the conventional constructive solution has been reduced in an evident way. Even the remaining electrical appliances are to be also considered as environmental safe, because they are supplied by renewable energy. The following table shows the estimated thermal loads calculated taking into account the control of solar gains provided by the roof geometry. The results demonstrate how the design objective of a seasonal thermal loads optimizing has been met. In addition to this, the building owner has decided an operation in a free float mode because, as consequence of all the avobe, the expected load for the period of normal use of the room (winter) is low and because the inability to afford by the auxiliary system the control of all the eventual external solicitations as an intermittent occupation or an uncontrolled air interchange throughout intermediate doors and windows. The deccision has produced an acceptable performance during winter time during monitored period and some overheating events during warm period (May-June) associated to high occupation or extremely warm climate situations, as it will be described in the corresponding chapter. Table 9.1. Monthly and annual load for MEDUCA roof
Month 1 2 3 4 5 6 7 8 9 10
Qtot (kWh/m2) 7.4 4.2 2.9 0.7 0.5 1.0 12.8 19.5 11.8 3.7
Qc Heating (kWh/m2) 7.4 4.1 2.9 0.7 0.4 0.3 0.0 0.0 0.0 0.3
Qr Cooling (kWh/m2) 0.0 0.1 0.0 0.0 0.0 0.7 12.8 19.5 11.8 3.4
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3.1 3.6 71.1
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1.3 3.4 20.8
1.8 0.2 50.3
Table 9.2 Monthly and annual load for the conventional sawtooh roof
Month 1 2 3 4 5 6 7 8 9 10 11 12 Year
Qtot (kWh/m2) 14.6 10.3 6.2 1.5 0.9 1.8 15.9 18.3 5.9 1.6 5.2 9.3 91.4
Qc Heating (kWh/m2) 14.6 10.3 6.2 1.5 0.5 0.3 0.0 0.0 0.1 1.6 5.2 9.3 49.5
Qr Cooling (kWh/m2) 0.0 0.0 0.0 0.0 0.4 1.5 15.9 18.3 5.8 0.0 0.0 0.0 41.9
Regarding electricity production, the PV system performance estimation shows tha the roof will produce in the order of 7800 kWh per year. The annual system performance is 9 %, the yield factor is 1,357 kWh/kWp and the performance ratio 0.71. The next table shows the distribution of the monthly electricity generation over one year. Table 9.3 Monthly electricity generation by PV plant
Month 1 2 3 4 5 6 7 8 9 10 11 12 Year
PV electricity (kWh) 490 487 636 660 702 715 729 792 783 627 589 556 7776
Accordingly, the PV production covers the expected maximum daily demand of electrical devices of the enclosure during the whole year, excluding November and December where the degree of fulfilment will be the 95 %. Evidently, as the use of the refurbished space is no
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continuous (week-ends, time between activities,..), an electrical surplus is obtained for the general supply to the building grid. 9.3.2 Monitoring Some sensors heve been permanently placed for continuous evaluation and visualisation of room temperatures, external and internal illuminances and the stack effect provoked by solar chimney. In addition to this, some specific one-time test were carried out for better evaluation on daylighting performance. Monitoring period September 1999 to end of the project. Instrumentation description
Continuous measuring: The equipment consists of a net of 4 dataloggers having 10 analog channels each one. The total of sensors, described in the table below is 34 Every channel was read with a frequency of 1s and averaged every ten minutes. The A/D of the datalogger has a resolution of 16 bits.
Table 9.4 Measured channels Measured quantity
n
Reporting
Accuracy
Air Temperature1 Indoor wind velocity2 Relative Humidity3 Global radiation4 Daylighting5 Wind velocity
26 2 2 3 5 1
10 minutes 10 minutes 10 minutes 10 minutes 10 minutes 10 minutes
r 0.3 qC 3 % r 0.05m/s 2% 5% 5% 5%
1
internal, external and globe (including stratification estimate), 2 working plane, intermediate and chimney output, 3 Internal and external, 4 global horizontal, vertical window and inclined surface, 5 4 outdoor (global horizontal, diffuse, vertical window and inclined surface), 1 indoor at working plane.
One-time measuring One time test consist of a grid evaluation of daylighting levels at 6 x 6 = 36 points in the space below the roof at a working plane over the floor and the measuring at 10 point along East-West corridor. Grid measurements are carried out by an hand-held MAVOLUX Luxmeter. The results of the monitoring activities are summarised in the following figures.
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1
1
0.8
0.8
0.6
Cases
Cases
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Outdoor Indoor
0.4
Outdoor Indoor
0.4 0.2
0.2 0 5
0.6
7
9
11 13 15 17 Temperature (ºC)
19
21
0 15 17 19 21 23 25 27 29 31 33 35 Temperature (ºC)
23
Winter
Summer
Fig. 9.1 Cumulative distribution function for observed indoor and outdoor temepratures
Jan
Feb
Mar L ux.East, 22º
Lux. Ea st, 22º
Lux.
5000-10000
10000-15000
0-5000 15000-20000
5000-10000
May
10000-15000
South, 22º 500-1000
1000-1500
2000-2500
0-500
500-1000
1000-1500
L ux. East, 22º
4000-6000
0-500
0-5000
4000-5000
5000-10000
10000-15000
0-2000
2000-4000
6000-8000
E Lux. ast, 22º
East, 22º
500-1000
1000-1500
South, 22º 1500-2000
0-500
500-1000
1000-1500
Lux.22º East,
5000-10000
1500-2000
Dec East, 22º
South, 22º
South, 22º 15000-20000 0-5000
4000-6000
Aug
Nov
South, 22º 6000-8000
South, 22º 3000-4000
E ast, 22º Lux.
South, 22º 2000-4000
2000-3000
South, 22º 1500-2000
Oct
Lux.
1000-2000
Jul
South, 22º 1500-2000
Sep
0-2000
20000-25000 0-1000
L ux. East, 22º
East, 22º Lux.
East, 22º
South, 22º 15000-20000
Jun
Lux.
0-500
E ast, 22º Lux.
South, 22º
South, 22º 0-5000
Apr
10000-15000
0-2000
2000-4000
4000-6000
6000-8000
Fig. 9.2 Results of monthly grid measurements of daylighting distribution under the new roof
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40
35
30
25
kWh 20 15
10
5
0 1
2
3
4
5
6
7
8
9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
day
Figure 9.3 Measured monthly production of PV plant (May)
9.4 Evaluation of indoor environment The analysis of normalised cumulative distribution function (CDF) of outdoor temperature and indoor temperatures shows as, during winter, both of them present a behaviour with a similar shape; indoor distribution is moved up about 4ºC, between eleven to twenty three degrees. However, for the summertime an important difference appears in the equivalent analysis: there is a cross point between indoor and outdoor CDF that implies appearance on some overheating cases. If instead of the above, the difference between indoor and outdoor probability density function (PDF) is evaluated; it’s to say registered case number’s of indoor temperature minus corresponding cases into the same temperature range for outdoor temperature, some extra conclusion can be extracted. As we can see at, during winter, 15 ºC is the boundary value that represent a higher amount of registered data corresponding to upper temperature into the courtyard (15ºC to 23ºC). In the case of summer time, the cross point between indoor and outdoor CDF implies appearance of three zones in difference temperature PDF representation. The resulting figure shows that the patio works as a bandpass filter moving most of cases to a range between 25ºC to 29ºCshowing as, excluding overheating cases, extreme temperatures are not usually reached into the enclosure.
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400
400
300
300
200
200 Diff. cases
Diff. cases
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100 0
100 0
-100
-100
-200
-200
-300 5
7
9
11 13 15 17 Temperature (ºC)
19
21
23
-300 15 17 19 21 23 25 27 29 31 33 35 Temperature (ºC)
winter
summer
Fig. 9.4 Observed probability density function of difference temperature
From this analysis it can conclude that the thermal performance of the patio in winter is very satisfactory. Indoor temperature is higher than outdoor and this increase is inversely proportional to the external temperature and most of the patio temperature cases are included between 15ºC and 23ºC. These results could be better if we take into account that during winter the roof that cover the courtyard was not completely closed. Regarding summertime, the observed behaviour is also satisfactory, excluding some situations with indoor extreme temperatures that could be improved optimising ventilation; this optimisation will increase the cooling degree and will move some cases included into the ‘cooling zone’ to the ‘thermal comfort band’. 9.5
Cost benefits
9.5.1 Economical value of energy savings Apart from the results in terms of energy friendly environment, the obtained economical benefits are estimated as the savings in regard to the air conditioning demand of the conventional constructive solution. In this way, taking into account the overall surface and the production of electricity, the total saving are (neglecting cooling demand) in the order of 2000 € per year in free float operation and in the order of 1200 € per year, in heating is used. Table 9.5 Savings estimations
Area kWh/ m2year Conventional Enhanced Savings Savings (free float) € /kWh Savings (€)
350 m2 Heating 49.5 28.8 21.2 49.5 0.08 1386
9.5.2 Payback estimation
Electricity (PV)
Total
22.3 0.08 624
2010
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Regarding the roof construction, the additional features have increased the costs of conventional solution in a 20 %, which produces payback period of 13 years for a free float operation and 30 years if estimated heating demand is afforded. The payback period for the PV plant is 77 years, if only electricity savings are considered. However, applying the national program to support renewable installations, that is 0.4 €/kWh, the payback period will be reduced to 13 years. 9.6 Overall conclusions/problems encountered/lessons learned The obtained experience after design and evaluation of the refurbishment project of the UALM courtyard has been quite satisfactory from the point of view of the building owner. It has been obtained a space fully ready for its expected use (2-3 acts per month are being held since roof construction) including some very useful and representative features, either from energetic and dissemination points of view. The design of the roof allows to the refurbished room to operate into the thermal comfort band without the help of auxiliary equipments during the maximun use period (winter). The savings in the air conditioning have been obtianed thanks to very simple enhancements of a conventional constructive concept, reducing in consequence the costs of the energy conscious measures. In spite of the satisfactory performance in the above approach, some improvements are to be still afforded from the designers to reduce the impact of extreme conditions during the warm periods.
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10 The Environmental Education Centre of Monte Catalfano, Bagheria, Italy by Antonino Giaccone, CNR-IEREN 10.1 Description of the project
Fig. 10.1 A view of the project
The Italian contribution to the MEDUCA Project has been the design and analysis of a new building, acting as an “Environmental Education Centre” (CEA or “Centro di Educazione Ambientale”), to be built in the immediate surroundings of the town of Bagheria (about 50000 inhabitants) at a few minutes (about 15 km) from the city of Palermo (about 750000 inhabitants). The project of the Centre is part of a bigger project regarding the creation of a suburban park covering almost the whole area of the Mount Catalfano promontory (about 270 ha.); the Centre will be situated at the entrance of the park as the only new building expected in this area.
Fig. 10.2 The Mount Catalfano promontory
The project, completed in 1997 with all its technical and financial tables and approved by the City Council in 1998, is since then inserted inside the Triennal Working Plan of the Province of Palermo for its financing. In order to give a symbolic meaning to the building by connecting its realisation to the rehabilitation of a degraded area 25000 m2 wide, it was decided to locate the Centre with its surrounding garden just above an abandoned landfill, located on the south side of the
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promontory of Mount Catalfano at about 170 meters above the sea level, just at the end of the vehicle road and at the border of the pinetrees wood.
Fig. 10.3 Site plan (before and after) The chosen site is situated in a good position as regards to the sun, surrounded by low hills on its northern, western and eastern side but completely open to the solar radiation coming from south. Objective of the project was the realisation and demonstration of an air-conditioned building characterised, through an appropriate bioclimatic architectural design, through the resort to renewable energy sources and through a rational use of energy, by a low heating, cooling and electric energy demand and thus by near zero consumption of conventional energy and fossile fuels and by a drastic reduction of CO2 emissions. Therefore the building project has included: a) thermal insulation of the building envelope b) passive heating through a large south-facing sunspace c) passive cooling techniques d) natural daylighting e) a solar assisted air-conditioning system f) a PV system Attention has also been paid to the use of natural construction materials, characterised by low embodied energy and by a low emission of indoor pollutants. Furthermore, the building will allow self-sufficiency with regards to the water supply and the disposal of wastes that will be treated on site through biological techniques (phytodepuration).
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Fig. 10.4 Plans and elevations
The L-shaped building will consist of two wings connected by a passage, both of them arranged over two floors and covering a total floor area of about 750 m2 and a volume of about 2500 m3; the entrance hall, the exhibition spaces, a bar room and the services will be located on the western wing of the building, while the classroom and the laboratories will be located in the main wing of the building oriented along an east-west axis. 10.2 The energy saving concept and the technologies 10.2.1 a) thermal insulation The building will be well insulated in order to reduce winter heat losses through the building envelope. In accordance with the day-time utilisation of the building, a lightweight building structure has been proposed with a large use of wood for the structural elements and the roof, glass and cellular concrete blocks for the exterior walls. Opaque walls of the building will be made with cellular concrete blocks (about 600 kg/m3), 17.5 cm. thick, having a thermal transmittance U = 0.73 W/m2 °C. Glazed surfaces will be made with two panes of reinforced (due to safety reasons) glass, 13-12-13 mm. thick, low-emissive coating, argon-filled gap, having a thermal transmittance U = 1.4 W/m2 °C. The roof will be made with two panes of wood, each one 2.5 cm. thick, insulated with granulated cork in the 5 cm. thick inner gap, having a thermal transmittance U = 0.58 W/ m2 °C. 10.2.2 b) passive solar heating All along the southern facade, a glazed double-height corridor at the ground level will act as sunspace, collecting the solar radiation during the heating season. The collected heat will be abducted to the rest of the building through large vents situated in the rear wall of the sunspace. 10.2.3 c) natural cooling
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Fig. 10.5 Sections Due to its location in the Mediterranean area and its utilisation also during the summer season, a particular attention has been devoted to the natural cooling of the building through: - solar protection - natural ventilation A seasonal shading of the glazings facing south will be provided through a row of deciduous trees and through a “pergola” of deciduous climbers placed in front of the sunspace, in order to eliminate solar irradiation during summer while admitting the solar energy during the winter season. All the exterior glazed surfaces of the building envelope will be largely openable while the interior partitions also will be provided with large vents in order to realise a natural cross ventilation of the whole building. Furthermore, by opening its front glazings, the sunspace can be transformed during the warmer periods into an open “loggia”. 10.2.4 d) daylighting The building will have large glazed surfaces to allow the natural lighting of all the interior spaces. In particular, the large north-facing glazed surfaces will allow for the daylighting of the classroom on the first floor and of the offices/laboratories on the ground floor. The sunspace on the south facade of the building will also contribute to the natural lighting of these spaces through its rear transparent wall. 10.2.5 e) the solar-assisted heating/cooling system It was decided that an electric water-to-water heat pump system will provide for the winter heating as well as for the summer cooling of the interior spaces. The heat pump system will be solar-assisted as, during the heating period, in order to improve its coefficient of performance and reduce
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its the electrical demand, it will use in its evaporator water pre-heated through a solar collector system,. A large pond located nearby and collecting the rainfall water from the whole park will instead be used for the cooling of the condenser during summer operation,. The solar collector system will make use of a seasonal storage, since the energy collected during the whole year by the 20 m2 of solar collectors placed on the roof of the building will be stored in an insulated 60 m3 water tank placed below the ground level to be used during winter. While the heating demand of the building will be reduced through envelope insulation and passive heating by the sunspace, the duration of the cooling periods and the cooling energy demand will be reduced through the natural cooling techniques described above as well as through the use of electric ceiling ventilators that will allow to achieve the same comfort levels with higher indoor air temperature levels. 10.2.6 f) the PV system Photovoltaic panels for electric power generation will be installed on the roof of the building, facing south. The overall area of the panels will be 135 m2 (180 panels, 0.75 m2 each) and the installed peak power of the system will be 12.6 kW. The system will be connected to the electric grid in order to exchange the electric power produced through the year by selling the excess energy produced during summer and buying the missing energy during winter. 10.3 Energy savings and reduced emissions A building occupation of 8 hours/day, 5 days/week, i.e. 40 hours/week has been taken into account. 10.3.1 Heating The overall heat loss coefficient due to transmission through the building envelope has been calculated, according to Italian regulations, as Cd = 0.619 W/m3 °C; it corresponds, for an external surface of the building envelope S = 1356 m2 and a heated volume V = 2135 m3, to a mean thermal transmittance of the building envelope Um = 0.975 W/m2 °C. The value calculated for Cd is considerably lower than the maximum acceptable value Cdmax = 0.876 W/m3 °C, imposed by an Italian law of the 1986 for the climatic conditions of Bagheria (HDD = 751 heating degree-days) and for the dimensions of the building (S/V ratio = 0.635), so that a reduction of almost the 30% over winter heat losses of the building envelope has been realized through the building insulation with respect to the prescriptions of the national law. Heat losses due to ventilation have been calculated for an air change rate of 1.5 volumes per hour in inhabitated spaces (0.5 volumes per hour in corridors and service spaces); the overall heat loss coefficient of the building due to ventilation is Cv = 0.486 W/m3 °C. The overall heat loss coefficient of the building is thus Cg = Cd + Cv = 1.104 W/m3 °C.
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For an outdoor design temperature of 5 °C and an indoor temperature of 20 °C, the peak heating load of the building is equal to about 35 kW. The solar energy collected by the sunspace during the heating period (that is for Bagheria 120 days from December to March) has been evaluated according to the specifications of Italian national rules UNI 10344, as 28433 kWh/year (102359 MJ/year). National Italian regulations prescribe a maximum “normalised energy demand” for winter heating that for the Centre is 145.3 kJ/m3 HDD, against the 21.9 kJ/m3 HDD realised by this project, with a 85% reduction over the prescriptions. An analysis has been conducted through the multizone simulation code TRNSYS 14.2 to investigate the thermal behaviour of the building. In the zones supposed to be heated, the indoor air temperature has been set to 20° C during the heating system operation periods. The following diagram shows heating energy demand of the building as calculated by TRNSYS. Heating energy demand 3000 2000 kWh 1000 Heating_E_D 0
Dec
Jan
Feb
Mar
Heating_E_D 1783,91 2571,55 1746,38 1038,34 Months
Fig. 10.6 Predicted heating energy demand A self-made computer simulation model of the solar collector system and seasonal storage has also been used in order to predict the solar energy collected and delivered to the building throughout a year. The results of the simulation have been: - solar energy incident on the collectors: 35790 kWh/year (128500 MJ/year) - collected solar energy: 11980 kWh/year (43117 MJ/year) - storage heat losses: 4920 kWh/year (17713 MJ/year) - energy transferred to the heat pump: 7060 kWh/year (25404 MJ/year) - electric energy needed to operate the heat pump: 2990 kWh/year (10767 MJ/year) - max temperature of the seasonal storage: 71.8 °C (in August) - average efficiency of the solar collectors: 0.34 - average efficiency of the storage: 0.59 - average efficiency of the collectors + storage system: 0.20
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average COP of the heat pump: 4.15
10.3.2 Cooling The cooling peak load of the building has been calculated as about 80 kWh, greater than the heating peak load; the heat pump system has thus been sized for cooling. The following diagram shows cooling energy demand of the building as calculated by TRNSYS; in the zones supposed to be cooled, the indoor air temperature has been set to 25° C during the cooling system operation periods. Cooling energy demand 4000 3000 kWh 2000 1000 0
Cooling_E_D June
July
August
Cooling_E_D 2349.396 3827.511 3344.768 Months
Fig. 10.7 Predicted cooling energy demand 10.3.3 Electricity With a yearly electric power yield of 16800 kWh/yr, the PV system has been sized to cover all the electricity needs of the building, including artificial lighting, appliances, the heat pump system, pumps adducting collected rain water to the building, etc. Low-consuming devices will be used for artificial lighting as well as for other electric appliances. Solar savings Saved thermal energy: from sunspaces from thermal collectors total Saved electrical energy: from PV panels
28433 kWh/yr 7060 kWh/yr 35493 kWh/yr 16800 kWh/yr
For a total floor area of 750 m2, it means about 47.3 kWh/m2 of thermal energy and 22.4 kWh/m2 of electrical energy saved each year. 10.3.4 Emissions CO2 emission factors: thermal
0.36 kgCO2/kWh
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electrical
0.55 kgCO2/kWh
Avoided CO2 emissions = (0.36 * 35493) + (0.55 * 16800) = 22017 kg CO2/yr For thermal energy, we considered 3 kgCO2 emissions/kg of oil and 10000 kcal/kg of oil with a plant efficiency of 0.75; for electrical energy, a local value has been used 10.4 Evaluation of indoor environment 10.4.1 Temperatures The air-conditioning system will provide for comfort temperatures inside the building.
Wintertime temperatures (from 19th to 20th of January) 35.00
30.00
25.00
T_ext T_sunspace T_hall T_lab2 T_clasroom
20.00 °C 15.00
10.00
5.00
0.00 1
3
5
7
9
11
13
15
17
19
21
23
25
27
29
31
33
35
37
39
41
43
45
47
Hours
Summertime temperatures (from 24th to 25th of July) 40,00
35,00
30,00
T_ext T_sunspace T_hall T_lab2 T_classroom
°C 25,00
20,00
15,00 1
3
5
7
9
11
13
15
17
19
21
23
25
27
29
31
33
35
37
39
Hours
Fig. 10.8 Predicted wintertime and summertime temperatures
41
43
45
47
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The above diagrams show some TRNSYS simulations results, with regards to the temperatures of some zones of the building (the entrance hall, the classroom, a laboratory, the free-floating sunspace) during some typical days of the winter and the summer period. A natural ventilation analysis showed how cross ventilation could be able to provide for comfortable temperatures during mid-seasons, when the air-conditioning system will not operate (see Ventilation Report). 10.4.2 Air quality The air-conditioning system will also provide for indoor air quality. The natural ventilation analysis showed also how, when the airconditioning system will not operate, cross ventilation, as well as very often single-sided ventilation, should suffice to provide a suitable indoor air change. (see Ventilation Report). 10.4.3 Light A daylighting analysis conducted through the SUPERLITE computer program, showed satisfactory illuminances and lighting uniformity ratios in the main wing of the building from the bilateral lighting coming through the windows on the north facades and the sunspace on the south facade (see Daylighting Report). 10.5 Cost benefits Costs of the project are shown below. Building Heating/cooling system PV system Other systems Landfill requalification Garden Total Eligible cost: Eligible cost minus EC support: Energy costs: thermal energy electrical energy
579501 Euro 146830 Euro 130698 Euro 194407 Euro 219014 Euro 67180 Euro 1337630 Euro 280187 Euro 168107 Euro
about 0.05 Euro/kWh about 0.125 Euro/kWh
Payback periods: with the EC grant: 168107/(0.05*35493+0.125*16800) = 43.4 yrs without the EC grant: 280187/(0.05*35493+0.125*16800) = 72.3 yrs High payback periods can be explained by the use of a still expensive technology like PV panels.
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10.5.1 Conclusions and lessons learned The Centre is expected to produce a strong impact on visitors (school classes, citizens, families, tourists), on local decision makers and on the general public, hosting activities (seminars, lessons, exhibitions, etc.) directly aimed at increasing people’s attention towards the topics of energy conservation and environmental protection, through a large classroom, exhibition spaces and laboratories managed by research institutions as well as environmentalist organisations. Moreover, the Centre will also be a demonstrative building, showing by itself the capabilities of bioclimatic architecture, renewable energy sources and rational use of energy to achieve in a Mediterranean climate suitable indoor conditions of thermal comfort in winter as well as in summer, of indoor light and of air quality, while reducing the consumption of non-renewable energy and the CO2 emissions related to its heating, cooling and electric energy demand. 10.6 Key project data Location: Site and surroundings: Owner: Architect: HVAC engineer: Electrical engineer: Structural engineer: Energy consultant: Cost - Total building: Cost - HVAC: Cost - PV system: Gross floor area: Number of storeys: Floor to ceiling height: Personnel load: Outdoor climate:
Mount Catalfano Park, near Bagheria Countryside, hilly Municipality of Bagheria Ing. Guido Nicastro Ing. Giovanni Pecorella Ing. Giovanni Pecorella Ing. Filippo Trifirò CNR-IEREN 1337630 Euro 146830 Euro 130698 Euro 750 m2 2 5.5 - 6.5 m (sloped roof) about 100 persons + 5 °C winter design temperature + 27.8 °C summer design temperature
10.7 References A. Giaccone, I. Santamaria, “A low-energy air conditioned building near Palermo”, Proceedings of the IEA/SHCP Task 25 Workshop “Solar Assisted Air Conditioning of Buildings”, Palermo, 1998
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11 EPLC premises by Gregory Economides, CRES, Center for Reneable Energy Sources, Greece.
Contact person: Gregory Economides, Dr. Civil Eng., CRES, Center for Reneable Energy Sources 19th klm, Marathonos Ave. 19009 Pikermi, Attiki, GREECE Tel : +30 10 660 3300 Fax : +30 10 660 3305 e-mail: groiko@cres gr
The new buildings of the European Public Law Centre (situated nearby Cape Sounion, Attica Greece) incorporate an energy design for optimal exploitation of locally available renewable energies for thermal energy supply and daylighting - ensured with an advanced energy management system. 11.1 Description of the project Building facts: x University Law institute - non-profit organisation x 1.500m2 total buildable area x Legraina, Attica - rural region, coastal land (Saronic Gulf) 40km southeast of Athens and 10km southwest of Lavrion x new building development x conservative building design with influence from building use (by a egislative institution) and from ancient Greek Classical order of nearby temple at Sounion
Figure 11.1 Perspective view of EPLC buildings.
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Figure 11.2. Ground floor plan of the multi-use building (bldg 1)
11.2 The energy saving concept and the technologies x x x x x x x x x
creation of favourable microclimatic conditions solar air-collectors for space heating geothermal heat-pumps for cooling optimised daylighting solar control natural ventilation ecological building materials improved indoor climate advanced building management energy system
Load Minimisation: In order to reduce building loads for heating and cooling and to ensure maximal exploitation of RES, specific load minimisation techniques were considered, such as: x bioclimatic design strategies (building location, orientation and shape, planning of inner spaces, window allocation and sizing, thermal mass) x reduction of building thermal loads - with protection of building shell (provided by thermally improved building construction materials environmentally friendly and double glazing) and minimised air infiltration of inner spaces (low thermal conductivity of window framing) x enhanced direct solar gains (from south openings) for partial energy supply during
99 Passive Cooling: Due to the specific use of the buildings, and in order to avoid complex systems demanding optimal user performance - only basic passive cooling techniques were considered, such as: x solar control of south openings - achieved with external permanent metal shading devices (overhangs with louvers controlling solar penetration on a seasonal basis) natural ventilation - achieved through properly orientated, situated and sized openings for cross ventilation (classrooms, offices, assembly hall, guest house rooms) and warm air removal from upper openings with the physical process of stack effect (library, assembly hall)
Figure 11.3 Cross section of the 3-floor library – Simulation of nighttime natural ventilation via CFD model
Daylighting: Significant load reduction of the artificial lighting for these buildings is achieved through the following daylighting techniques: x natural light penetration from all openings with controlled transmittance of the south openings with overhangs and light shelves x defined reflectance/transmittance ratio for all spaces x raised rooflights (assembly hall and library) for uniformity x lightwells at multi-storey spaces (library) for light penetration at lower levels
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Advanced Energy Management System: The reduced auxiliary energy needs (due to building load minimisation) - covered by the energy supply systems (solar aircollectors and geothermal heat pumps) - is in overall regulated with an advanced building energy management system, providing and/or controlling the following: x information management x maintenance management x electricity management x light control x air quality control x ventilation control x cooling control x heating control x environmental monitoring (microclimatic conditions) Thermal Energy Supply System: Two basic energy systems are included in the building energy design, in order to supply the auxiliary energy demand for heating and cooling. The systems function in combination, as they are planned to supply energy to particular building parts and for particular seasonal needs: x solar air-collectors (with a total area of 100sq.m.) are situated onto the multi-use building roof for pre-heating and re-heating of the warm air circulated via air ducts driven by an air-handling unit (classrooms and assembly hall) x geothermal heat-pumps (approximately 120kW capacity) supply remaining heating needs (other building spaces and guest house), as also all cooling needs of both buildings - with water distributed to fan-coil units x water solar collectors (total are of 25sq.m.) cover domestic hot water needs of the guest house
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Figure 11.4. The hydraulic layout of the configuration selected in the building application
Figure 11.5. The aeraulic layout of the configuration selected in the building application
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Figure 11.6. DHW solar collectors
11.3 Energy savings and reduced emissions According to the initial proposal, where the prospective energy values of the buildings came up from the simulation analysis, the energy saving in electricity, cooling and heating is shown in the below table. This energy saving derives from the special design of the systems and technologies which use the available renewable energy sources of the area. When the monitoring phase was completed, the energy saving in heating, cooling and electricity was 89.3% instead of 81.5%, 79.6% instead of 81.4% and 45.7% instead of 42%, respectively.
Table 11.1. Design phase
Monitoring phase
Typical blg Energy Peak load Bioclimatic Energy Peak load 2000-20001 Energy Peak load kW kWh kW kWh kW Heating kWh bldg 1 151246 97 bldg 1 25195 93 bldg 1 & 2 16551.6 45.5 bldg 2 3497 5 bldg 2 3497 5 Sum 154743 102 Sum 28692 98 Sum 16552 46 kWh 92778 15061 107839
kW 143 13 156
Lighting kWh bldg 1 & 2 96836 Sum 96836
kW
Cooling bldg 1 bldg 2 Sum
bldg 1 bldg 2 Sum
Sum
kWh 15061 4952 20013
kW 13 6 19
kWh bldg 1 & 2 22013.618
kWh 56190 56190
kW
kWh bldg 1 & 2 44248 Sum 44248
sum
22013.6
kW 30.5 30.5 kW
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It is mentioned that the results concerns the specific period 20002001, where the summer was warmer than the mid-climate of the same period the last 10 years. In addition, the buildings were not occupied all the summertime because of vacation, and lack of full EPLC activities in the buildings. The places that are used daily are the offices, whilst the classrooms and the multi-use hall (conferences, postgraduate courses etc) are used according to the EPLC’s activities. Total energy consumption is (11.03kWh/m2 a –heating + 29.49 kWh/m2 a – lighting + 14.67 kWh/m2 a cooling) = 55.19 kWh/m2 a. This value compared with the initial proposal’s one (page 232 of annex of the Contract) is better than the expected (72.7 kWh/mw2 a), and respective measurements in heating/cooling schools of Greece (66-80 kWh/m2 a). In terms of the air quality (emissions) in the buildings, the below figure shows the air polluters’ reduction because of the energy saving. This figure refers to the measurement and function (2000-2001) period of the buildings. The above diagram indicates the estimate of seven air polluters’ emission reduction in the initial consideration and in the measurement period.
impact of energy savings to emissions 1200 1106 1123 design
monitoring
1000
kg/year
800
600 446 452 400
212 215 200
3
3
4
9
4
9
3
3
0 CO2 *10^3
SO2
CH4
N2O
Nox
CO
NMVOC
Figure 11.7. Reduction of annual gas emissions
11.4 Evaluation of indoor environment The indoor environment (thermal and optical conditions) has been considered sufficient according to the following graphs coming from the measurements of the monitoring phase, as well as to the completed questionnaires by the students, the teachers and the personnel and PMV & PPD factors analysis.
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35
30
Temeprature [oC]
25
20
15
10
5
0 5/3/2001 12:00
6/3/2001 0:00
6/3/2001 12:00
7/3/2001 0:00
7/3/2001 12:00
8/3/2001 0:00
date office 1st floor South
Reception ground floor South
External Air Temperature
Figure 11.8. Temperature fluctuation during 2 typical winter days (hours of blg operation 8:30-15:30)
During summertime, PMV & PPD factors were measured. Air temperature, relative humidity and wind speed measurements took place in 6m height, in a typical classroom (CR)-ground floor building No1, the library (LIB)- ground floor building No1, an office (OF)first floor building No1. The mean radiant temperature considered equal to the air temperature, the activity degree is 1met for light office work, and the costume degree is 0,5clo for a typical summer costume. The mean values of PMV & PPD in every place when the cooling system was on, were: &5 (6/7/2001) PMV=0,4 PPD=8,8% &5 (7/7/2001) PMV=0,5 PPD=9,8% CR (10/7/2001) PMV=0,7 PPD=15,5% LIB (4/8/2001) PMV=0,6 PPD=12,5% Ȁ03 (4/9/99) PMV=0,7 PPD=17,8% OF (24/9/2001) PMV=0,7 PPD=17,3% Questioning the users and the personnel “what is your opinion about the thermal comfort?” the answers are following: Very Comfortable: 21.6% Comfortable: 27.0% Acceptable: 40.5% Uncomfortable: 8.1% Very Uncomfortable: 2.7% Therefore the PPD is 10.8%. The calculations’ results for July are the following: when Ȟ=0.0m/sec, PPD=10.7% and when Ȟ=0.10m/sec, PPD=9.6%
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Thus, the general view is that the indoor conditions are acceptable by the pupils and the personnel. 11.5 Cost benefits
11.6 Conclusions and lessons learned By the end of this project, significant conclusions came up in terms of the planning and the application of the systems. The Bioclimatic design turned out extremely effective taking into account the energy saving and the indoor conditions. During summer time, some glare problems came up in the southfacing rooms of the Guest House (building No2). The shading system by steady horizontal blinds was not sufficient; therefore heavy curtains were placed inside the glazing. The HVAC system of the buildings, because of the complex Project cost HVAC system Water well solar collectors BMS system daylighting dev, passive ets
drx 33,040,000 3,976,600 19,594,829 23,246,000 15,000,000
Euro 96,962.58 11,670.14 57,505.00 68,220.10 44,020.54
Total cost
94,857,429
278,378.37
Project savings Heating Cooling Electricity Total savings Pay back period
kWh/year at 35 drx /kWh or 0.11 Euro /kWh 138,191 4,836,685 15,20 85,825 3,003,875 9,44 52,588 1,840,580 5,78 276,604 9,681,140 30,42 9,15 Years +45% (not contin.use) 13 2 < 16 53 Y (d i )
innovative and ostentatious systems, needs the BEMS system so as to operate efficiently. In addition, the degree of survey is greater than in conventional buildings, because of the moisture, due to the adjacency with the sea, cleaning of the collectors’ surface from the dust. During the installation and testing operation of the systems, the installation of extra devices and protective accessories required, such as a clay collector device by the geothermal well, because of the special component of the ground. Ending, it is mentioned that some problems countered during this project, which caused major delays in the schedule. Some of these problems are mandatory change of the buildings’ place, change of the structural study because of the modification of the antiseismic regulation (after the destructive earthquake of 7th September 1999),
106 problems because of the existence surface water in the ground and procedures subcontracting public works in Greece. 11.7 Key project data Location:
Greece, Attiki, Legraina (40 km from Athens) Lat. 23o, 45’ Site and surroundings: Semi-urban with low-rise buildings. Flat Owner: European Public Law Center Research project: CRES - Center for Renewable Energy Sources Architect: Konstantinos Pontikopoulos and Assoc. HVAC engineer: Michalis Karagiorgas, Dr. Mech. Eng., CRES Electrical engineer: Structural engineer: Contractor:
Michalis Karagiorgas, Dr. Mech. Eng., CRES
Agriro Athanasiou Civil Eng. subcontractor (air & water solar collector constructor SOLE SA). Construction work: Started in September 1999. Completed in November 2000 Cost – Total building: 1.500.000 Euro Cost – HVAC: 120.000 Euro Gross floor area: 1582,8m2 + 426,6 m2 Number of storeys: 2 plus roof, distribution ducts and solar air collectors. Floor to ceiling height: 3.0 – 4.0 m (sloped roof) Personnel load: 100 pupils + teachers and staff (full oper.mode)
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12 References 12.1 Litterature Main topic Author Energy
Energy
Energy
Energy Energy Energy Energy
Indoor climate Indoor climate Indoor climate Indoor climate Indoor climate Indoor climate Indoor climate Indoor climate
Title/type of publication
Organization/ Year Language Conference Elmberg, A. Improving the energy efficiency - Göteborg 1996 Swedish etc. The experience from Flatås school Energi in Göteborg/report Amatruda, J. Schoolspec Classroom Evaluation Healthy 1997 English etc. Tool: A Software to Analyze Buildings, Energy Efficiency, IAQ etc. in USA Modular Classrooms/paper Good indoor climate & lower NUTEK 1994 Swedish operating costs - Renovation of schools/report Övferholm, E. Equipped for the school/report NUTEK 1995 Swedish etc. Requirements on lighting in NUTEK 1994 Swedish schools/report Magnusson, J. Less energy and more comfort - to NUTEK 1996 Swedish the smallest detail/article Effektiv nu Vidar Lerum Integrated passive solar heating SINTEF, . 1997 English and daylighting analysis of two STF22 design alternatives as compared to A97564 a base case design/report Persson, M. Recommendations when planning Akademiska 1996 Swedish etc. educational rooms/report hus Hellberg, A., To see, hear and breathe in Boverket etc 1996 Swedish etc. schools - A handbook on the indoor environment/report Larsson, R., Indoor climate in schools Byggforsk1993 Swedish etc. Measures in schools in ningsrådet Växjö/report Gulliksson, H. Good indoor environment in Byggforsk1992 Swedish etc. schools ningsrådet Nordquist, B. 17 healthy buildings - Good Byggforsk1996 Swedish examples: daycare centers and ningsrådet schools/report Lytton, M. Indoor Air Quality in Schools: A Healthy 1997 English Practitioner’s Perspective/Paper Buildings, Canada Myhrvold, AN Pupil’s Health and Performance Healthy 1997 English etc. Due to Renovation of Buildings, Schools/paper Norway Bascom, R. Health and Indoor Air Quality in Healthy 1997 English Schools: A Spur to Action or a Buildings, False Alarm/paper USA
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Indoor climate
Angell, WJ etc.
Building Factors Associated with School Indoor Air Quality Problems: A Perspective/paper Ventilation Limb, M. Ventilation in Schools - Annotated Bibliography/report Ventilation Per O. Design of Fan-Assisted Natural Tjelflaat and Ventilation. General Guidelines Eystein and Suggested Design for EnergyRødahl. Efficient Climatization-System for School Building in Grong, Norway./report Ventilation Blomsterberg, Modern passive stack ventilated Å., Sikander, schools – evalution of ventilation E., Ruud, S. and moisture Cost and Lefevre, J. S Reducing Operating Costs and comfort Improving the Student
Learning Environment
Healthy Buildings, USA AIVC
1997 English
SINTEF, STF22 A97557
1997 English
Byggforskningsrådet
1997 Swedish
1997 English
The National 1999 English Ass. of Energy Service Companies and The US DOE, Rebuild America Program.
12.2 Other projects with the same focus Sustainable energy technologies for schools, EU – ENERGIE Programme, Energie-Citès, www.energie-cites.org Retrofitting of Educational Buildings – REDUCE Energy Concept Advisor for technical retrofit Measures, IEA Energy Conservation in Building and Community Systems, Annex 36, www.annex36.bizland.com
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13 Appendix 1: MEDUCA SCRAP BOOK
