Duct Leakage Calculation Technique And Economics

Transcript

AIVC 11868 TABLE OF CONTENTS MAIN PAGE 4182 T-Method Duct Design, Part V: Duct Leakage Calculation Technique and Economics Robert J. Tsai, Ph.D. Herman F. Behls, P.E. Member ASHRAE Fellow/Life Member ASHRAE ABSTRACT The procedure of incorporating duct leakage into the T-method simulates leakage as an additional parallel section with zero length for each duct section. The assumption that additional air leakage creates additional system resistance is wrong. Leakage always reduces, not increases, system resis­ tance. How fan power consumption changes due to leakage depends on the fan performance curve. Leo P. Varvak, Ph.D. changing the operating point on the fan curve. It is impossible to manually analyze actual flow due to the distribution of air leakage through a duct system. A supply system may have places where static pressure will be negative due to the change of air velocity and static regain or static loss and/or turbulence such as that caused by an elbow. Practically, this sucks air in from the outside instead of leaking it out. For practical reasons, calculation of this phenomenon is avoided by assuming zero supply ductwork infiltration. Methodology was developed to add duct leakage to the T-method previously developedfor both the design and simu­ lation ofduct systems. It is shown that in most cases the sealing of ductwork is economical. Duct sealing is not recommended when electricity cost is less than 2¢/kWh and sealing cost is greater than $1.5/m2. A simple rule is: the higher the system cost, the greater the need for ductwork sealing. The technique developed was tested using the sample problem in the "Duct Design" chapter of the 1985 ASHRAE Handbook-Fundamentals (ASHRAE 1 985). INTRODUCTION Theory and Calculation Technique For the series of T-method duct design research projects, the following papers have been published: "Part I, Optimiza­ tion Theory" (Tsal et al. 1 988a); "Part II, Calculation Proce­ dure and Economic Analysis" (Tsal et al. 1988b); "Part III, Simulation" (Tsal et al. 1 990); "Part IV, Duct Leakage Theory" (Tsal et al. 1 998). Duct Simulation. The purpose ofT-method simulation is to determine the flow within each section of a duct system of known duct sizes and fan characteristics. Incorporating duct leakage means that downstream airflow at each section is different from upstream due to air leakage through the duct walls. T-method with duct leakage incorporates the following major procedures: This paper covers calculation technique and leakage stud­ ies to determine the economics of sealing ductwork. There are two applications ofT-method duct design: opti­ mization and simulation. T-method duct optimization is based on calculation of duct sizes that minimize the life-cycle cost, i ncluding energy, duct, and fan costs. T-method duct simula­ tion calculates actual airflows and the fan operating point for given systems with known duct sizes and fan performance. Due to leakage, the actual flow rate is usually less than designed. To compensate for lost air, fan flow is increased by LEAKAGE IN A BRANCHED DUCT SYSTEM 1. System condensing. Condense the branched tree system into a single imaginary duct section with identical hydraulic characteristics. Duct leakage is simulated as an additional duct section connected in parallel to each duct section in a duct system. 2. Selection ofan operating point. Determine the system flow and pressure by locating the intersection of the system char­ acteristic and the fan performance curve. Robert J. Tsai and Leo P. Varvak are with NETSAL & Associates, Fountain Valley, Calif. Herman F. Behls is with Behls & Associates, Arlington Heights, Ill. THIS PREPRINT IS FOR DISCUSSION PURPOSES ONLY, FOR INCLUSION IN ASHRAE TRANSACTIONS 1998, V. 104, Pt. 2. Not to be reprinted in whole or in part without written permission of the American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc., 1791 Tullis Circle, NE, Atlanta, GA 30329. Opinions, findings, conclusions, or recommendations expressed in this paper are those of the author(s) and do not necessarily reflect the views of ASHRAE. Written questions and comments regarding this paper should be received at ASHRAE no later than July 10, 1998. 3. System expansion. Expand the condensed imaginary duct section into the original system with flow distribution. Leakage at the i-section is simulated as an additional x-section that is connected in parallel to section i at the node. Pressure loss for the leakage x-section is the same as for section I, and flow is ilQ. This is the main idea of incorporating duct leakage i nto the T-method. Therefore, the same formulas that are used by the T-method without duct leakage are used for the T-method with leakage incorporated. The difference is four parallel sections at each node instead of two. Condensing duct sections connected in series yields Equation 1 (Tsai et al. 1 990, Equation 1 2). -2 -0,5 -2 K1-2 = (Ki + K2 ) (1) Condensing duct sections connected in parallel (Figure 1) yields (2) Condensing a tee (Figure 2) yields Equation 3. The selection and e xpansion procedures for T-method duct simulation with leakage incorporated are the same as without leakage (Tsai et al. 1 990). Duct Optimization. The T-method incorporates the following major procedures: I. System condensing. Condensing a branched tree system into a single imaginary duct section with identical hydraulic characteristics and the same owning cost as the entire system. 2. Air-handling unit selection. Selecting an optimal fan and establishing the optimal system pressure loss. 3. System expansion. Expanding the condensed imaginary duct section into the original system with optimal distribu­ tion of pressure losses. Two sections connected in series are compressed using the following equation (Tsai et al. 1 988b, Equation 1 . 32). 0.833 _ 0.833 l.2 K 1-2- (K I + K2 ) Two sections connected in parallel are condensed using the following equation (Figure 1). (5) Condensing a tee (Figure 2) yields (6) The selection and expansion procedures for T-method duct optimization with leakage incorporated are the same as with­ out leakage (Tsai et al. 1 988). Leakage Percentage Study Five-Section System. Leakage was studied using a five­ section duct system (Figure 3) with the following parameters: absolute roughness 0.0003 m (0.001 ft), air temperature 22°C (71 .6°F), kinematic viscosity 1 .54 x 1 0-5 m2/s (1 .66 x 10-4 ft2/s), and air density 1 .20 kg/m3 (0.075 lbm/ft3). The system studied had significant leakage (CL = 48), and the airflow/surface area ratio was 21 . 1 (L/s)/m2 (4.2 cfm/ft2). For these conditions and a system static pressure of 200 Pa (0.8 in. wg), the ASHRAE Handbook indicates that leakage as a percentage of system airflow is 9.6% (ASHRAE 1 993, Chapter 32, Table 7). Leak­ age calculation is based on approximate formulas (Tsai et al. 1 998). The three following calculations are performed to analyze leakage phenomena. The first calculation is for a system with no leakage. Results of simulation are presented in Table 1 . The results are also represented by point A in Figure 4. Total flow rate at the system terminals (outlets) is 1 .423 m3/s (3016 cfm), and the fan motor power is 0.7 1 kW. The second calculation is for a system with CL = 48 (Table 2). The total system leakage is 0.088 m3/s ( 1 86 cfm), and the system operates at point B (fan speed constant). Leak­ age is 6 . 1 9 % and is represented by points b through d. However, since the fan operating point was shifted to the right, the actual leakage is only the value between points a and d. This leakage is 0.039 m3/s (84 cfm), which is only i/ i/ 0------ M------ Figure 1 2 k 2 l X1 9 " � 1-.:5 � Two duct sections in parallel with air leakage. (4) 6 Figure 2 6 � 2 0 � Junction with air leakage. 4182 BACK TO PAGE ONE _.,. 00 N TABLE 1 Five-Section Duct System with No Air Leakage DATA INPUT • fMftOW', m3/s hn snuura.. tn..WG • • Fan llftlcieney _ __ Plan_ ) I t . N P Ch2 T U Rough. Factor L8ngt L---.;: 14.0 � %.22 202 o.u 1.12 311 o.as 215 0.13 MC1tor Ell'ic::l9nq' ·-··--· Absotut. Rougime•-· I A 1::11 low C- Coeff. .....---...----i> 0.254 • 0.257 O.IO 12.11 0.170 0.65 ... O.J20 0.18 16.0 D.231 0,65 19.1 0.'37 1.50 Ana V•l. I Frietlon I o.n I 0.24 I by DI ·� c 1i .. 15 �IMtltt-Surflce RATIOS T A D u ct S I it a Hlllght Width Dtam. m • 0.0001 71.S 22..DG C • • 1..20 mJls • D.D7S 1..scE-Sm:vt• 1.ME... USO a.110 kW' ----·--···-·-···-··-··· 1.271n.WG • D Kinunmtic V111costtv••••• Eran..•·--··--·-···-······ 3015 ctm 1.75 0.0003 • Air Tempenbn--·-· lA•U. C\ass ···-··-·-· ..... """'"'-··-·-·-··-·-· • Sections__ . Duct �- s' s� D.75 1 •.Ul m31• � Jfl.1 Pa • _ Cfan___ 1.42 1.02 S2ti a.a 0.12 330 i1 '" v..DCltJ-Prusurw-Ru1s1:1nce Velo- Surdty race m2 .......II" ft F 1U1s ft2ll. ,. "' ...... . Loss mis D ,. is - .,. ... " 0.11 O.!MI 0..255 0.0211 0.0211 D.5761 131i.2 D.0000 D.0596 D.0596 o.757 0.21111 0.161 D.170 0.170 IA t.11 0.020 0.02.a o.4021 112 a.DODO 0.0191 D..243 0.64 0.54 1.20 0.320 0.320 I.DI 11.41 0.0206 D.0206 D.222 5''-0 o.01e1 0.0000 0.0665 0.36 0.21 1.27 1 1 Q,231 0.231 11.S 12.DI D.0223 0.0223 0.50fl o.4l1 o.437 n..l 9.50 0.0193 0.0193 1,C37I 71 "' Kt 0..1241 .,. ... .. JO " n l X P A N SI H G PruliUN Flaw •nowa An,.. lllnodu &cas --Slatk P•th l..eakag9 Uppe r L.vwer Pra.ln Flaw UPS* Lower Pr.Loss P9. Pe Pa m!I• mlf• .m319 Pa T•• Coeflici.nts t..abge Tab.I P• DwMIVav 0..211111 tOI 10.11111 .. -· � Acbml Friction Sect. F • ct or Chanc:btr Air V..ocitr •• C ONDENSING I I PHv � OU .a.2 33.t 0.000 D.H5 D.1195 0.2 .a.2 29.2 0.000 D.223 D.223 0.2 D.6451190.1 136.1 15.2 0.000 D.911 0.918 0.0000 0.0367 0.0367 D.lSS D.DDOO D.1251 D.0791 1.000 l m31s % Qd 136.1 121.D Flow .. Tmmlnals Noloa Dd 136.1 190.3 " COMPARISON 190.1 .0.2 51.8 0.000 D.506 D.508 311.1 fl0,1 200.t D.DOO 1.423 1.423 I I I Cl.2 1 0.11 5 .0.01 D.223 0..02 0,506 'A.Ct 1.'23 -G.01 ____ __ _ _________ __._ - ··---.a.-----· ------�----' _ Airftowtsurrace Rnlo, lhlm2 • 21.1 ' l&IQge - D.00 %,Qsum 1.423 , Qsum • % TABLE 2 Five-Section Duct System with Leakage Class 48, Fan Rotation Speed 1 D AT A IN PU T Fan 11ow, •:II• Fan Pf9Mlft., ln,WG • Fan .nici.ncy • o.•2 t.G2 D.75 0.13 330 329 1.42 311 0.85 U2 2..22 ""' 0.12 275 0.13 llotarElncienc)' •m•M­ • AbsDlutm RaughneH­ Alr T•rnperabni.--. l.N.klll'I Cl&H -···-·-·­ 1A1t m31s • 312.1 Pai .. �- ---.... ��--Duct I N P s U Lengt Sec Ch1 s sl u:...:_ Ch2 m 14.D t w II l ' D 1.251n.WG 1 A T I Rough.�� Fllclor Height Wsdth Di•m. m • m 111 I .. w D 0..254 • r A 11 RATIOS t1 Ffk.. C.. m c 12.ll D.170 ll.65 ... 0.320 D.111 16.0 0.231 0.65 19.11 0.431 1.50 by tfon I I I D.075 l't3l9 - 1.!ME..S rn2ts - t.a£.A 0.710 0.724 ·SurAir dty face Velocity m m2 mis Vel� lt2h kW Friction Sect. F •ct or Charachir Aclaal ..... . . I.DH Pa 2i" 14..ll 0.75 0.11 D.921 D.255 0.211 0.24 0.211 0,1151 0.170 0.170 &.A 0.62 0.54 1.1'rl O.JZil D.320 I.DI 0.3-t 0.28 1.23 D.1.31 D.231 11.e 0."37 0.437 27..2 Z2 µ ::i:� C ONDENSING :n P 0.5761 129.9 0.0008 0.0595 0.0603 0.758 9,61 0.02436 0.0244 0.4031 130.8 D.0004 ll'.JHl1 0.01ts 0.2:M 1l..2'$ 0.0l'DS' 0.0206 0.2221 52.1 0.0005 Q.12'.9 0,0571 0.507 1as.o o.ooor 0.DlU D.0374 D.355 1.0381 131.1 D.0025 Cl.12551 0.0!32 1.000 D.02227 0,0223 D.01924 D,0192 A N ltn 0.0219 8i X K 0.021119 9.64 21' E p I I 30 N G o• dnodu :n SI FI Awrmge at nodes Static L.ukage Upper Lower PNlsurm- Aow lJpp9r Pl Pa P• mlls mJls T •• Coetricients 10.43 11L 1$ PAis1ure - eo.llic..nts Lnb!illl Total v ..... �MIA V.JV; C 0.0001 ft 71.& F p ,, n iiit7 1.--. , -� JO I Dlametar.Suffacs II Velodtr-Pressw-e-Restshlncs Coen. 0.80 D.257 10 • • ... KlntrMtic. Vlt;costty._,. a.in...... _______ Mfan.........-_••.,.,._. --- 3117 efrn m 22.00 C t.20 m31's • Air OMr;llJ.----- ·--­ Qf•n_,_ Pfan.,...__ D.75 D.0003 LOW9r m3ls nu � &cess Path Pr.Lou P• .... 121.l ·1.6 31.7 0 009 0,683 0.174 •·• 128.3 .2.11 H.5 0.004 o.zzo 0.215 2..& 0,1451181..2 128.3 11.5 0 009 0.113 O.IOJ Alrllowrsurtac• Ratio, u.Jm2 • I 111.2 -s.a 41.4 0.010 D-.503 D.4M 312.1 111.2 191.5 0.056 1A11 1.416 21.1 • Laalc•Qll • 6,19%,,Qsum I 1.383, 3.a �2 ?.l_J COMPARISON Aow .. T..-mlmls -· m:W. .,. 1 .Q!__� I Qaum• 0.69.5 -3,04 0..223 -3.04 o.506 -z.s7 1.423--2.ICJ% BACK TO PAGE ONE r / L � ,� ,, -< --- /,,,_. T Figure 3 5 , " :, r / J / --cF-- --- .,\, x 1 2---0 -- 6 Five-section duct system schematic. 1.34 BHP• 0.793 ow lo.1114. Q •l.•Z'ICo 1.327 1.32 . :;: z ,- 0 1.30 � uf a.:: ·::i w a.:: a.. !;( t; 1.28 !::! 1.272 1.26 .251 c 1.24 3300 3200 28GO 6.19% FLOW, CFM 193 6.42% LEAKAGE CLASS 0.=2 D.5DI \H.D 0.0007 o.0367 o.ou• o.m 192.1 ·U 11.3 0..010 0.511 Cl.508 "'"" 131.1 D.0025 0,USI O.OUJ 1.000 '31.7 112.1 203.0 o.osa 1.516 1.451 11.13 1.93 O.'D2055 D.0112 G.0192 51.D AlrftowtSur'f:.C. Ratio, Lt""'2 • lA , 22.5 , Lamoe • 6.�%_Qaum 1.US, Cbwn• 1.423•0.12% BACK TO PAGE ONE of parent sections. Tenninal sections always have low pressure. The average static pressure at tenninal sections is the lowest in the system and at tenninals is zero. There­ fore, a branched tree system will always have less leakage than one duct of the same surface area and pressure loss. Air leakage can be simulated by a number of small holes in ductwork. Part of the air will be leaked in or out through these leakage sites. This will move the system curve to the right, creating a new operating point on the fan curve. Therefore, the fan will be actively involved in this process by increasing fan airflow and reducing fan pressure. This can be seen in Figure 4 where operating point A moves to point B. How fan pressure is reduced depends on the fan performance curve. Therefore, the assumption that addi­ tional air leakage into a system creates additional system resistance is wrong. Leakage always reduces, not increases, system resistance. How the fan power consump­ tion increases depends on the fan performance curve. There is a traditional, but incorrect, belief that in systems where no allowance has been made for leakage, fan motor power increases as the cube of the ratio of the air quantity (AABC 1 983). Therefore, it is commonly stated that leak­ age can be compensated for by additional fan horsepower based on the following fan law equation, where Mis the fan motor power and Q is fan airflow. (7) Using flow rates from Tables 1 and 2 or Figure 4, the new fan motor power requirement Mis or 6.M = (l.1-0.71)100/0.71 = 55.6%. However, Equation 7 is not appropriate for comparison since the system with no leakage and the system with leak­ age have different system curves. The results of the calcu­ lation summarized in Figure 4 shows that the actual increase in power is only 10.5%, not 55.6%. Point B on the fan curve (Figure 4) presents the actual leakage rate of 6.2% in the five-section system for unsealed ducts (CL= 48). This does not mean that the design airflow at the tenninals will supply 6.2% less air because the fan curve moves right, increasing the system airflow rate. As shown by Table 2 and Figure 4, the total leakage is 6.2% of which 3.4% is above the design flow rate because, for a constant fan speed, flow increases as the system resistance decreases. Thus, the system leak­ age relative to the design flow rate is only 2.8%. ASHRAE Example. The simulation procedure with leak­ age is tested on the duct system presented in the 1985 ASHRAE 6 Fundamentals (Example 5) and is called herein the "ASHRAE example." The return ductwork includes Sections 1 through 6; the supply, Sections 7 through 19. General input data are: (R) ..... .. ... .... ....... .. ... ... .... ... ... 0.0003 m (0.001 ft) Air temperature (t) .... ..... ............ ...... . . .......... .... . . . .. . . . 22°C (7l.6°F) . ..... . Kinematic viscosity (v) ....... . ......... 1.54 x 10-5 m2/s (1.66 x 10-4 ft2/s) Absolute roughness . .. Air density (p)............................................... 1.2 kg/m3 (0.075 lbmlft3) . There is a SISW (single inlet, single width) centrifugal fan with air-foil blades and a 380 mm (15 in.) wheel operat­ ing at 2635 rpm. The fan operating point for the no duct leak­ age condition (CL= 0) is Q1 ,,,, = 2.01 8 m3/s (4277 cfm) and Pfan = 7 1 1 . l Pa (2.84 in. wg). The fan curve is represented by the following five fan rating points: Qfan = 1 .59 m3/s (3369 cfm), Pfan = 1 12 1 Pa (4.48 in. wg) Qfan = 1 .76 m3/s (3729 cfm), Pfan = 996 Pa (3.98 in. wg) Qfan = 1 .92 m3/s (4068 cfm), Pfan = 832 Pa (3.33 in. wg) Qfan = 2.09 m3/s (4428 cfm), Pfan = 623 Pa (2.49 in. wg) Qfan = 2.26 m3/s (4789 cfm), Pfan = 373 Pa (1.49 in. wg) Calculations (Table 4) were performed for the same fan and a system leak age class of CL= 48. Leakage creates a new system curve and a new operating point: Q1,,,, = 2.042 m 3/s (4327 cfm) P1011 681.4 Pa (2.73 in. wg). This operating point require· 2.22 kW, which is 2.7% less than the kW for the same system wit h no duct leakage. Leakage is 0.164 m3/s (346 cfm) for the return subsystem and 0.122 m3/s (257 cfm) for the supply subsystem. Considering that this is just one combined system divided into two parts, return and supply, air leakage is calculated as average: (0.164 + 0. 122)/2 = 0. 143 m3/s (302 cfm), or 7.0%. , = In the second calculation, the fan speed was increased to compensate for leakage in both subsystems. The solution (Table 5) is: Q1011 2.160 m3/s (4577 cfm), P1011 760.3 Pa (3.04 in. wg). Total leakage is 0.279 m3/s (592 cfm), which is 1 2.9% of the total airflow. Fan motor power is 2.65 kW, a 1 6.2% increase over the no-leakage system. Compared to the flow rates for a no-leakage system, the return subsystem is 1 .6% less air and the supply subsystem is 1 .7% additional air. For this system, according to ASHRAE (1 993, chapter 32, Table 7: CL= 48, airflow/surface area rntio = 2 cfm/ft 2), the predicted leakage rate is 46.1 %. Using the cube fan law (Equa­ tion 7), the fan motor power requirement increases 22.6%. Our study shows that the actual leakage rate is only 13.1 % and that the fan motor power increases 16.2%. = = The same system was calculated for a leakage class (CL) of 12. The return subsystem leakage is 2 . 1 % and the supply subsystem leakage is 1.3%. The increase in fan motor power is only 4.0%. 4182 � 00 "' TABLE 4 IN PUT ASHRAE Example with Unsealed Ductwork, Fan Rotation Speed 1 DATA Fanflcrw, � Fanpruaun.ln.WG • . Fon-ncy . 1.11 1.71 t.n o.u 1121 - 1.12 m us 2.0I m o.u 2..K ST3 D.75 ........ Blidooicy -··-­ 0.11 • - R....-.... AWT--·- 1.abgo C.U. __ -..__ ,,,...__ ' l 2 I � 5 p u T • D _ Alt Donal!y__ -111acaolly_ .szl 2.nln.WG 7 • • 11 10 IJ • ,, c- Laab Flow Alu Vet. Duct t 11• Rvugh. ...... Fac&or HitlCll"ll i'&lii) � Co.ff. c:a..u m m m m m SI "2 L .. " w D c Oy Frie- m • ...... " .. ... V•la- clly m • t.a rnst. • 1..uE..Srn21s• .... 2.221 kW •T II l.DOOt fl 7.1.1 F ...,, fDla ,.HE... ,, ,,. .. .... r vov Z2 2l Z> 2• " Z1 C ONDENSING ,._,,,.. Frlctl en Alt SwSeel. - Voloclty F• c:tor Cllu>oter mis rn2 .. ... ftJls Velodt:y�aure-Rffh.tanc1 DUmntr-Svrflm RATIOS Duo1 Ch2 • Ban----­ ------ " T " • ... ""' ....... ....... ...... Pa ... - �·.... Laolalgo TOlal "" � 21 E n X P A N )0 'I u SI N G Flaw al nodes ExcOoo Statl� t..Up Patil Lowt:r Pruan Flow "-' '-- Pr.i.-o Po Po 11131• Pa ....... �Awn1ge ho �... Upper Po rU .... Pd �" nu � "" ll ... COMPARISON � .. Termlnala - -· % Ocr � 0 0 U.31 o.:105 .. .. "' o.u t.oo o.n D..305 0,305 21.l 1.45 D.021• D.0211 1.121 110.D O.DOJ2 a.our o.oc90 a.1st 105.0 -4.0 1Dl.5 0.033 0.708 D.11.J 5.0 0.721 7.1 1 • 0 2'.71 0.2111 O.IC ... o.2' o.aa o.s• 1.203 0.203 15.J 1.93 O.IWU 0.023' 0.755 100.7 0.0017 D.0217 0.2U 1DS.O -1.S 12.1 0.011 o.n. 0.211 1.1 0.2'1 1D.5 1 2 1.n O.:t05 0.50 41 0.•7 0.5D O.M 0.305 0.305 7.0 11.00 0.020ll 0.0207 O.J03 100..1 1,0010 o.°"' 0.0111 OMG • • 0 1.52 1.13 " D.H :S.74 0.11 0.110 I.Al u 2.C7 O.H02 0.021D2 ..... s.r 1.041 S.7 5 • 0 2U2 O.SSI 1.7' u 1.51 0.11 0.71 US& O.SSI 22.1 10.21 0.02011 0.0202 1.ID7 1.oa I> D.510 0.111 0.023$ ..... 1115.0 25U 0.011 0.157 O.UI n.1 o.oon 0.1111 0.1121 1..DDC 24.0 -5.7 11.1 0.002 0."1 O.NI OJ10211 o.1752 1.on' 1.520 -· :au 171.1 o.oaa 1.0l5 O.H1 2'1.t ZOU m.1 I > s 11.lt D.432 0.2C &1 o.•u DAU 11..1 11.71 t.1111 0,0119 CUD 11..S O.ICl22 0.2172 0.11K 1.IOO 31:U 0.050 2.0Q 1."2 ' 0 0 ur O.JOS 3.11 " a.u o.s1 1.05 0.305 f.305 •.1 2A1 O.Ol'38 0.0144 1.151 1J.1 l.I003 o.Mlti o.o.ui o� ll.J 15.1 22.1 0.002 o.171 0.175 11.1 0.193 .... I 0 0 1.22 D.305 5.H Q D.4& Ul1 0.15 D.305 O.lOS 1.l 1.M o.02511 a.om 1.755 0..0001 O.Mtl 0.0:n4 O.MJ' n.l 19.5 21.0 0.001 0.1'3 D.IC:Z 11.5 0.151 I.I t 7 I 7.52 0..254 0.559 3... " D.tl 1.IJ e.SJ o.Kt o.m 12.4 2.29 0.0237' 0.0217 1.m t,>;-1 1�3 0.0010 0.092' o.ocu 1.000 .... ll.l lU 0.009 0.321 0.120 10 9 0 1J.72 0.254 D.305 >Al " 0.20 o.u 0."5 0.277 0.314 19.3 4.3' 0.02S13 0.0231 USO U.1 0.0012 0.0465 O.G3M 0.111 SU ...0 .... D.015 0.3'3 0.321 11 • • 1.1' D.254 0.356 1.51 a OM 0.50 D.11 0.296 0.331 11.1 S.71 0.02171 0.0211 0.751 H.1 D.CI005 0.1712 0.0117 ....7 11.1 11.5 11.7 0.005 0.114 O.IOI 11.5 0.IJJ .. 0 0 1.71 0.254 0.156 0.17 '8 D.55 0..50 1.1D 0.2H 0.»9 1.2 U2 0.021, 0.0214 0.493 11.5 0.0002 D..DHI 0.0970 0.553 71.1 1U 4.1 0.001 D.700 0.751 11.4 0.7U 0.:114 •.•71 20.1 7 .17 0.020JS 0 .020J 0.272 20.0 0.0014 D,JOlf D.15'2 0.802 "-' 71.1 53.l 0.011 1.112 1.174 o.1ru 1.ns ,, ,, 12 10.'1 0.254 0.711 ..0.01 41 O.IO 1.00 a..IO .. ... ' l.2 " 10 13 , ... a.2sc 0.111 0.00 41 'o.K 1.IO D.17 0.:11• 0.•78 I.I 1.60 0.02 0.02 ._,. 11.1 G.0005 um D.175 115.1 N.7 SU o.ooa 1.7.. ,. 0 0 1.57 0..203 0.152 1.l6 41 a.a 0.11 0.10 0.17' 1.119 I.I J.CI O.D2UI D.DZSS D.SST 22..7 Cl.GOO.a o.02Jt a.ow o..nt '1.J 17.1 21.2 0.003 0.111 0.112 17.1 0.121 7.3 " 0 0 S.10 0.20J D.151 UI .. 8..50 D.f7 I.TS 0.174 0.111 u •.OS 1.DK1t 1.0212 0."71 D.O O.OOOS UJIO 0,02<3 O.lll 41.J 17.7 11.5 l.D02 0.121 D.124 17.7 1.131 1.0 " 15 11 l.U o.m 0,151 l.31 .. D.12 IUI OM D.ZOJ 0..243 ... S.2t 0.02111 D.0215 1.DJJ 73.7 0..000 7 0.0211 0.0255 0.12$ 115.1 au 11.1 O.OOI 1.250 0-2'1 • 14 17 7.01 0.251 0.711 2.11 41 O.lt O..SI 1.11 G.J74 1.471 13.S 11.11 0.01111 0.01H 1.A71 U7.J 0.0011 l.1UO 0.1112 1.000 J.&3..4 115.1 155.f 0.024 2.017 1.ltJ " 11 0 l.H 0.432 0.711 2.30 ... 1.00 D..537 a.a25 I.A l..51 D.11&11 1 .0111 Ul1 1 12.1 1.0000 0�7 0.1013 1.000 .,., J43.4 -·· 0.025 2.0C:Z 2.017 0.1 o..cs 1.n 0.551 0."2 1.2 0.0773 ,_ 111.A Ul "' 2.011 UT "' 2.011 14.00 % 2.011 �.O .u -5.1 !Fons 11 Fan static prusuni RatioUWm2 • • Laaklge by ASHRA£ . _, 2.IM2..slo • N Sections Sec Chi • A1.5Pa • . . o.oau m 21.DO C A5.2 Pa ..., ...1% R.tum: L..b99 • """"" laolalgo • Total or avwaea: L..kap • 2.0Q D.114 m3l1 O.t22ndls 0.:ZHndls 1.171 1.120 1.IH BACK TO PAGE ONE 00 TABLE 5 ASHRAE E xample with Unsealed Ductwork, Fan Rotation Speed 2 DATA IN .. LIT t.51 1'Jt Fan now, mSla • F•n pnt.aU19, ln.WG • • Fan .nkMcy ar.n-- I I N - s.cCM • • ' 2 Cl1Z • p u IH o.u I Dud lto " Actual - CN'"m ...... . -· Codi!:- Lou Pa 1.uu111 lotal � It> 0.0 2 1 UZI 12.J.O D.D03Z O.OCST 1.- D.Tst H6.T a.one 0.755 111.2 l.OD17 1.0211 D.023S 0� 111.7 0.0:1111 O.l03 U1A 0.0010 O.- 0."'7t OAMl 229.1 O.T• UO 0,7' U.305 0.305 ZU 41 0.24 OM t.5l O.ZOJ 0...203 U.2 ' 1 z T.32 o.sos 050 OI UT 0.SO 0.8' 0.305 O.l05 T.O 1.13 41 t.K 2.T• O.%S UtC Ull 2.1 ' .ca I.St 0.51 0.74 0..... UK ll.I tD.79 1.00 0.'32 t:US O.OZOCZ .... K llt ,. 21 E X "' P A N SIN .. ., Static.__..,.. Flow - -· .......... Uppor - .. COMPARISON ..... i..-r Pr.U.. ... .. T-la - rn!I• P• I'll P• "" � . .... ... .u 115.0 ..... ua D.7'2 u o.na :u .a.s II.% D.019 u•T 0.221 z..s 0.2•1 ... Ul.7 215.1 0.011 1.012 t.M3 ... 1.NI O.l .... Od o.oz UGO D.2 l.IOG3 e.1111 0.1121 1.oaa IU .&.I 15.1 D.001 t.o.t7 t.MI 0.02011 o.ozot t.m 202.1 l.DDJG 0.0752 O.D725 0.520 lll.1 .... 197.J D.04I t.M5 1MT uz 0.02004 n G Flow Aw,.ge Up,... L._ p.....,. D.UI 41 O.M ,, ......... .. .- TH Cod"idonta 1.:u o.02377 UI D.202 t.7 2l 1 0.00 IU05 U.JSS 22 CONDENSING r 23.TT 0.610 Frli;tlon F•clor .W• :ZA.JI 0.510 ,., Vu mZ • uz ,,, .. ... D zuz 11 ,... 0 • 1..20 m3l9. 1.175 � 1.s&E...Srn'J&• t..llE-4 ft2la D.125 Z.151 llW "' .. D • ft 71.S F city z 0 • � m ' ' l.OD01 • 22.DQ C Vtlodty-Praauni�eMIClna 51' ... 1.75 D.DOU m .. $1 " ... 2 5 11.n u.w •.:z• a 0.432 15.1 14..11 0.118"' G.01H 1.m H.l 1.0023 0.217• 0.1117 1.000 1zs.s m.1 _, t.OS. 1.llO 1.10I 1 0 • 4.ZT 0.205 .... " o.s. 0.51 1.CKi D.305 UOI ... u1 o.ouot o.o.u1 1..i51 1!U 1.0002 O.o.&15 D.CMll O.SSS 17.2 1.1 I.I 0.001 0.111 t.llO 1.1 0.113 1.1 ' • 0 1.ZZ 0.305 !!Ii.II .. '·" G.51 O.M D.JOS O.l05 1.2 2.12 1.02"6 0.02•'1 l.TSS 1!1.. 0.000 1 O.Ol!IJ O.OJM IM7 1T.Z u 1.3 0.000 D.155 1.15' 1.1 0.156 t.3 ' T • 7.IZ D.2SC D.551 3.A3 oll D.K 1.U 0.53 D.M9 D.425 12.4 2..46 o.02u1 o.om 1.175 1U 0.0009 O.otJA O.DMI t.000 23.5 O.Otl< US! O.:IU 0 1J.12 0.254 D.JOS .... .. 0.%0 ..... us D.277 0.314 15.S U3 0.022tT 0 .022 U50 59.1 D.DG12 O.DC'5 0.0311 0.1!1 , ..., 22.1 • H.T ZT.I .... 0.0 12 D.SU a.ssz 10 11 • • •�14 0.254 D.l5& 1.56 41 O M o.su o.n 0..296 O.S39 11.1 7.%1 0.021.. 0.0217 0.756 H.2 0.0006 0.0712 D.0711 1.'47 IS.2 -3.1 17.1 0.005 0.153 D.MI 3.1 0 .13 3 ..z.• 12 0 0 l.T1 0.254 0.356 UT .. 0.55 0.50 t.10 0.216 0..339 1.2 1.15 D.D21J1 a.ozu Ul2 ,.., 0.0002 o.- o.imt D.552 IU ·U I.I D.002 UOI 0.006 1' D.TM �2.1 13 11 12 11.17 0.254 G.711 -G.01 &II D.ID 1.DO O.ID O.l74 0.479 20.I 1.14 0.0202' O.DZOZ o.zn 22..5 0.001Z 1.3097 G.15'2 t.I02 H.T IU 35.1 a.a" UTT t.AU 1.t 1D " UT 0.25-4 0.711 O.OI ., 0.17 1.DO 0.17 D.37"' 0.471 ... to.n o.o t n 2 o.otn 0.14' 11.0 0.0005 UZZS 0.tTU I.ITS 106.2 IT.J JO OJlllS . .... 1.MZ ts 0 0 1.57 D..203 0.152 1.3' '8 I.tr 0.17 0.70 0.11• D.1H ... �- 0.12G'l:S 0.0211 I.SST Zl..2 1.000.C. 11.0Zlt O.OW D.A71 21.2 ... 10.t 0.002 l.tll 1.121 2.1 0.121 ..,_, 11 • 0 l.10 D.203 D.152 ,_., 41 Ut O.OT O.TT 0.11' o.1n u UJ 0.015H 0.02' IA'1t MA o.ooo:z o.0'2'0 o.om u21 Zl.J 1.t t.I D.OOt 0.1M l.1ll 1.t 0.12Z .... . 1T 15 " 1.1• l.l05 0.152 121 .. o.u 0.2' .... 0..203 o� . .. $.SJ ·� D.02'2 un U.2 0.-0 D.02" 0.0255 UZS tou 23.0 U.7 D.OOT G.28' 1.%51 II t4 1T T.ot 0.%0< O.T11 1.11 OI O.lt 0.51 1.TI un o.m tu 11.TT G.11115 O.OIM UTT ZS/1.1 l.001t 1.1:131 0.1121 1.100 "4.1 n.1 125.1 1.021 1.135 1.11• 11 11 • . ... 0.432 D.711 2.00 41 t.DO 0>37 0.1125 ... UI 0.01Ut 0.0111 1.Stl cu 0.0000 D..1547 a.1au 1.000 43£.t J12.1 m.1 D.OZT 1.llO 1.U3 0.1 11.45 o.n ·- 0.1-U 0.% 3..U 0.0202$ 0.D2tlZ 1.oa2 O.OTT3 1..000 7I0.3 UI % 2.011 12.11 1'. J.011 -1.1 t.7 0.0 fin I 1S Fan atatlc pr11aaun1 • Rollo u.irnz • t..aklige byA9�E • 00 N rnJl'I • ,,. • 1.71 L � � � ;'.':; :Z.1H 71G.l • PfatL-- D.75 OIS.Z I'll I... 41.1" Retum:L..-kl1119• Supply.�... t.bge • Tota.I or•wnp: 1.t&O O.IT•rn!lo 1.1a.c rn3la 1.2n,... 1.111 1.0$1 L011 .... .. 1.011 BACK TO PAGE ONE . s eattle. s> oiral Duct ' ,._ � .... ._ �r----_ ----., ---._ -r---r------_ ----·11- ........___ � ----.__ - .. - �.. •- O CM = L ..... Figure S a 1,00 ------- .... � , Sealing Cost, $1m2 200 r--. -I .., � ------ ------- ........___ .. _, .... r--_ -----t------------------.h..._, ----....._ --r---.. r---.... New York Sniro L Duct .... - r--- ------ '-"' ----;..._ -- ,... Sealing Cost, S/m2 "" ----- llO - 0™ = � 0™=� 0�=� 0™=� 0™� OCM=3..._ OCM=5....,_ O CM = 7-+- OCM = 9 Parametric economic study for Seattle and galvanized ductwork. Sea11lc Stainless Duct Figure Sc Parametric economic study for New York City and galvanized ductwork. New York Stainless Duct . � �--- ,____ ... .... 1.00 !� 200 Sealing Cost, $1m2 -- OCM= L..... OCM=3-.... 0 CM=5....,_ OCM=7-- 0CM=9 Figure Sb Parametric economic study for Seattle and stainless ductwork. Duct Leakage Economics Study The system studied for leakage effects is the ASHRAE example in the 1 985 ASHRAE Handbook (Tsal et al. 1 988a). The difference in calculation is air velocity, average sectional static pressure, and leakage. Table 6 summarizes the results for an unsealed system, where CL = 48 for the rectangular duct­ work (supply subsystem) and CL = 30 for the round ductwork (return subsystem). The calculations are shown by Figures S a through 5d for various ductwork, energy, and sealing costs. The sealing cost for the sample problem is $2.5 per m2 ($0.25 per ft2) of duct surface. Comparison of the results to a zero-leakage system is presented in Table 7. For sealed duct­ work the return (C1., = 3) and supply (C� 6) subsystem leak­ age is 0 .0 1 2 m3/s (25 cfm) and 0.025 m Is (53 cfm). The total. leakage, supply and return, is 0.037 m3/s (78 cfm), or 2.0% of fan flow. In this case, the system flow rate for sealed ductwork is only 1 .6% higher ( 1 .9 1 m3/s vs. 1 .88 rn31s). = 4182 ... .... - � .... .___� ... Sealing Cost, S!m.2 ... "' -- OCM=l-.- OCM = 3-- OCM=S...... OCM=7-- OCM=9 Figure Sd Parametric economic study for New York City and stainless ductwork. For unsealed ductwork, as summarized in Table 7, the return and supply subsystem leakage is 0. 125 m3Is (265 .4 cfm) and 0.2 1 1 m31s (447.9 cfm). The higher leakage for the supply system is due to the longer duct. The total leakage, supply and return, is 0.336 mis (71 3.3 cfm), or 16.1 % of fan flow. However, the preferred procedure is to compare the leakage percentage for the return-supply system based on the maxi­ mum leakage i n one of the e systems. In this case, the system flow rate for unsealed ductwork is only 1 0% higher (2.09 m31 s vs. 1.88 m3/s, or 0.2 1 1 m3/s). For unsealed ductwork, the percentage of increased operating cost ($2239 vs. $20 1 3) is proportional to the increase of fan flow (2.09 vs. 1 .88), or 10%. Life-cycle cost increased 3.8%. A parametric study was performed using the ASHRAE example for various cities, duct costs, and leakage classes. The analysis was an optimized duct system with leakage. Life­ cycle cost was determined by Equation 8, which includes oper­ ating cost (Ep), owning cost (Es), and sealing cost (As.Ss). 9 BAC K TO PAGE ONE 0 TABLE 6 ASHRAE Example Optimized with Air Leakage F•T.WP......,. ...... ,.. ,..,.. ... Mt.J ... .. ..,. .... _,. -­ ...... .. ...... ,.,v.. -­ »T...--. 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IT.M tl2.IO Z>l.1 l.&S IS1 111.1 17 ..,.. 1.177 - - T.... 81.9 111.9 llO.I au Al.A - Ps.n - - T- . . TABLE 7 t..aOcr1 I.DJ 7..W US04 f..111 UM H •.a o.mt Ut1 0.111 o.m 1.otn 471 � UIS 0..471 1.47'0 ... ... D.IOM I.IQ 11..N •....,, l.M'1 ,... 1N..1 ...... o.. .uu Ull N.1 1.•Z:IZ I.II "'°· 1tt.1 1.210I t.12 .... ·� 11.&2 $ Life-Cycle Cost Comparison for Sealed and Unsealed Ductwork MAXIMUM LEAKAGE LEAKAGE LEAKAGE fm:ii/st F AN Fl.OW LEAKAGE l�'/:11) SUPl'l.Y .... o;; N RET\JRW 0 SYSTEM COST TOTAL DUCT SURFACE lm1) TOTAL TOTAL 1%) m1/a OWNING OPBIATING " • • I LIFE CYCLE SEALING COST ltl " DUCT POST • " 0 None 1 .88 0 0 0 0 0 6084 201 3 8097 0 1 82.4 0 8097 Sealed Outtwork 1 .91 0.025 u . 01 2 0.037 2.0 0.025 1 .3 6121 2040 8161 0.8 1 83.5 459 861 9 6.4 Unsealed Ductwork 2.09 0.21 1 0. 1 25 0.336 16.1 0.2 1 1 1 0.0 6 1 77 2239 8416 3.8 1 85.2 0 841 6 3.9 I BACK TO PAGE ONE E = Ep + Es + A s · Ss (8) The operating cost can be presented as basic operating cost (Eb) and its operating cost multiplier (OCM). Ep = Eb(OCM) (9) The parameters that were used as variables for graphical interpretation (Figures 5a through 5d) in the life-cycle cost analysis are: Duct cost (Sd). Galvanized ($33.361m2), stainless ducts ($127.981m2). Operating cost multiplier (OCM). 1, 3, 5, 7, 9. This coef­ ficient identifies the operating cost in a practical range for duct systems with different electrical energy costs multiplied by system operation time per year. It is used for graphical interpretation (Figures Sa to 5 d) . When Ep presents actual operating cost and the lowest operation Li me of a basic system, OCM is equal 10 I . Set.ding cost (Ss). 0, 0.50, 1 .00, 1 .50, 2.50 $1m2, where the * highest cost ($2.5011112) is from SMACNA. On the other t hand, accord ing 10 a Midwest s hee t metaJ con.tractor, the duct sealing cost is i nsignificant. Sheet metal contractors usually seal longitudinal duct seams on roll forming machines. The contractor stated that the increase in cost is insignificant unless special sealers are used. Therefore, the lowest sealing cost considered is zero. Basic electrical energy cost (Ee) is a part of the basic operating cost (Eb) selected for two cities-the cheap­ est, which is 1 .89¢/k.Wh for Seattle, and the most expen­ sive, which is 1 6. 34¢1kWh for residential buildings in New York and 1 1 .88¢/k.Wh for industrial buildings in San Diego (based on Electric Sales and Revenue, EIA, Washington, DC). The results of the study are summarized in Table 8 where theoretical conditions at no leakage are included for compar­ ison. It was found that higher system leakage increased both operating and owning costs. Tables 9 through 1 2 present the results of the parametric study. Figure 5 is a graphical repre­ sentation of the results. There is a small range where duct sealing is not recommended: operating cost multiplier (OCM) is less than 2 (which is mostly exhaust systems), electricity cost is less than 2.00¢/k.Wh, and sealing cost is higher than $ 1 .501m2. when the operating cost multiplier (OCM) is less than 2 (generally exhaust systems), electricity cost is less than 2.00¢/k.Wh, and sealing cost is greater than $ 1 .501m2. A simple rule is: the higher the system cost, the greater the need for ductwork sealing. ACKNOWLED G MENT The work reported in this paper is the result of cooperative research between the American Society of Heating, Refriger­ ating and Air-Conditioning Engineers, Inc. (ASHRAE), and NETSAL & Associates. NOMENCLATURE A == As == c t Telephone conversation with Mr. C. R. James, vice president, the Robert Irsay Company, Skokie, Ill., November 28, 1 990. 4 1 82 local loss coefficient, dimensionless == leakage class, dimensionless == == duct diameter, m (in.) equivalent-by-friction diameter of rectangular duct, m (in.) equivalent-by-velocity diameter of a rectangular duct, m (in.) E == present worth owning and operating cost, $ Eb == basic operating cost, $ Ee == electrical energy cost, $/kWh Ep == operating cost, $ Es == owning cost, $ == friction factor, dimensionless H == duct height, m (in.) L == duct length, m (in.) life-cycle cost, $ f LCC == M == fan motor power, kW (hp) OCM == operating cost multiplier, dimensionless == downstream pressure, Pa (in. wg) == fan total pressure, Pa (in. wg) == average static pressure, Pa (in. wg) == system total pressure, Pa (in. wg) == == == == == Methodology was developed to add duct leakage to the T-method previously developed for the design and simula­ tion of systems. It is shown that in most cases the sealing of ductwork is economical. Duct sealing is not recommended services. SMACNA, Chantilly, Va., March 2 1 , 1990. == == CONCLUSIONS Telephone conversation with J. H. Stratton, director of technical duct cross-sectional area, m2 (ft2) duct surface, m2 (ft2) == == == Sd == Ss == V upstream pressure, Pa (in. wg) present worth escalation factor, dimensionless airflow, m3Is (cfrn) downstream flow rate, m31s (cfrn) fan flow rate, m3Is (cfrn) upstream flow rate, m31s (cfrn) absolute roughness factor, m (ft) duct cost, $1m2 ($1ft2) terminal airflow with zero leakage, m31s (cfm) sealing cost, $1m2 ($1ft2) == air temperature, "C (°F) == mean air velocity, mis (fpm) II BACK TO PAGE ONE = average air velocity, mis (fpm) = duct width, m (in.) dP, Ill' = total pressure loss, Pa (in. wg) dPp, Mp = path pressure loss, Pa (in. wg) dPex dQ,t:.Q = = p = v = excess path pressure loss, Pa (in. wg) flow leakage rate, m3/s (cfm) air density, kg/m3 (lbm/ft3 ) 2 kinematic viscosity, m /s (ft2/s) TERMINOLOGY The following terminology is adapted from Horowitz and Sahni (1 976). References are to the system illustrated by Figure 3. Children and parent. Duct sections connected at the same node. The parent section is the one that collects or distributes the total flow. The rest are children sections. In Figure 3, Section 3 is the parent with two children, Sections 1 and 2. Parent Section 5 has two children, Sections 3 and 4. Path. A set of descendants connected in series. Paths from node 3-4-5 are 4, 1-3, and 2-3. Paths from the root node 5 are 1-3-5, 2-3-5, and 4-5 . Tee. Sections linked at the same node. The tee 1 -2-3 consists of Sections 1 , 2, and 3 . Terminal sections (nodes). nals : Sections 1 , 2, and 4. 12 Sections connected t o the termi­ Tree. A system of duct sections connected at nodes with no circuits. REFERENCES AABC. 1 983. Duct leakage and air balancing. Technical Publication No. 2-83. Washington, DC: Associated Air Balance Council. ASHRAE. 1993. 1993 ASHRAE Handbook-Fundamentals, Chapter 32, "Duct design." Atlanta: American Society of Heating, Refrigerating and Air-Conditioning Engi­ neers, Inc. ASHRAE. 1985. ASHRAE Handbook-1985 Fundamentals (l-P edition), Chapter 33, "Duct design." Atlanta: Amer­ ican Society of Heating, Refrigerating and Air-Condi­ tioning Engineers, Inc. Horowitz, E., and S. Sahni. 1 976. Fundamentals of data structures. New York: Computer Science Press. Tsai, R.J., H.F. Behls, and R. Mangel. 1988a. T-method duct design, Part I: Optimization theory. ASHRAE Transac­ tions 94 (2). Tsal, R.J., H.F. Behls, and R. Mangel. 1988b. T-method duct design, Part II: Calculation procedure and economic analysis. ASHRAE Transactions 94 (2). Tsal, R.J., H.F. Behls, and R. Mangel. 1990. T-method duct design, Part III : Simulation. ASHRAE Transactions 96 (2). Tsal, R.J., H.F. Behls, and L.P. Varvak. 1998. T-method duct design, Part IV: Duct leakage theory. ASHRAE Transac- 4182 BACK TO PAGE ONE � 00 "' TABLE 8 Ductwork Sealing Life- Cycle Cost Comparisons for Various Cities - - CITY F C 0 N S U M E R D U C T Electr i c M A T E R I A L Cost LEAKAGE C c/kll·h) 1. New Yorlc, Resident i a l , G a l van zed New York, Res i dent i a l , G a l van zed New York, Resident i a l 2. 3. 4. G a l van zed None Sea l ed Ductwork Unsealed Ductwork San D i ego, San D i ego, I ndustr ia l , S t a i n l ess I ndus t r i a l , S t a i n l ess None Seal Ductwork San D i ego Industr i a l , Stai n l ess Unsea l ed Ductwork Seat t l e , Resident i a l , G a l vani zed None Seat t l e , Resi dent i a l , Ga lvani zed Sealed Ductwork Seat t l e, Resident ia l , G a l vani zed Unsealed Ductwork Seat t l e , l ndustr a l , Sta nless None Seatt l e , l ndustr al, Sta nless Sealed Ductwork Seatt Le lndustr a l , Sta n l ess Unsea l ed Ductwork 2. San D i ego, I ndustr i a l , S t a i n l ess New York, Resident i a l 3. San D i ego, I ndust r i a l , S t a i n less San D i ego, Indust r i a l , S t a i nless Seattle, Industria l , Stainless Stainless Seattle. Industrial. !.;.) E Cost F l ow Cm'ts> Pressure (Pa) SUPPLY RETURN Cni'/s) TOTAL errts> cni'ts> TOTAL MAX. (%) Cm'/s) MAX. (%) 33.36 33.36 33.36 1 .88 1 .90 2 . 06 285 .3 289 . 0 288 . 5 0 . 000 0 . 022 0 . 1 79 0 . 000 0 . 007 0.075 0 . 000 0 . 030 0 . 255 0 . 00 1 . 56 12.36 0 . 000 0 . 022 0 . 1 79 0 . 00 1 . 17 8 . 70 1 1 .88 1 1 . 88 1 1 . 88 1 27 . 98 1 27 . 98 1 27.98 1 . 88 1 . 90 2 . 07 552. 5 567 . 1 565 . 0 0 . 000 0 . 023 0 . 187 0 . 000 0.010 0 . 105 o. odo 0 . 033 0 . 292 0.00 1 . 73 14.11 0 . 000 0 . 023 0 . 187 0 . 00 1 . 19 9 . 05 1 . 89 1 . 89 1 .89 33.36 33.36 33.36 1 . 88 . 1 . 90 2 . 09 732 . 1 754 . 6 749. 9 o . ooo 0 . 024 0 . 202 0 . 000 0 . 01 2 0 . 1 18 0 . 000 0 . 036 0.321 0 . 00 1 .89 1 5 .37 0 . 000 0 . 024 0 . 202 0 . 00 1 . 28 9. 70 2 . 03 2 . 03 2 . 03 1 27 . 98 1 27 . 98 1 27 . 98 1 . 88 1 . 92 2 . 20 0 . 000 0 . 037 0.303 0 . 000 0.019 0. 171 0 . 000 0 . 056 0 . 474 0 . 00 2.92 21 .58 0 . 000 0 . 037 0 . 303 0 . 00 1 . 95 1 3 . 81 1 75 1 . 2 1821 . 6 . 1760.4 Duct Cost C O S T Operat ing Owni ng L i fe Cyc l e I Duct Sur ace � Sea l ing Cost T 0 T A L C 0 S T s " s " ($) s " None Sealed Ductwork Unsealed Ductwork 1 6 . 34 16 .34 1 6 .34 33.36 33 . 36 33.36 8928 8839 8958 55.35 5672 6135 0 2 . 47 1 0 . 84 14464 1 45 1 1 15093 0 0 . 33 4.35 267.6 265 .0 268 . 5 0 662 0 14464 1 5 1 73 1 5093 0 4 . 90 4.35 None 1 1 . 88 1 1 . 88 1 1 . 88 127.98 127.98 127.98 26284 26043 26192 7797 8095 8n4 0 3 . 83 1 2 . 53 34080 341.38 34965 0 0.17 2 .60 205 . 4 203 . 5 204. 7 0 509 0 34080 34647 34965 0 2 . 59 2.60 1 . 89 1 ,89 1 .89 33.36 33.36 33.36 6329 1643 1715 1 867 0 4 .39 13.62 7972 7989 8223 0 0 .21 3.14 1 89 . 7 0 47P 0 7972 8459 8223 0 6.10 3 . 14 2 .03 2 . 03 2 . 03 1.27 . 98 127 . 98 127.98 205:16 1 4221 0 24m 25427 25396 0 2.62 0 4011 0 24 m 25827 0 4 .20 25396 2.50 Seal Ductwork Unseated Ductwork None G a l vanized G s Sealed Ductwork Indus t r i a l , Stai nl es � A ($/of) Seattle, Resident i a l , Ga lvani zed Seat t l e , K Cc/kll·h> Seat t t e , Resi dent i a l , Galvanized Seatt l e . Resi dent i a l 4. Galvanized A E 1 6 . 34 16.34 1 6 .34 E l ec t r i c Cost LEAKAGE New York, Res ident i a l , G a l vani zed New York, Resident i a l , G a l vani zed L S Y S T E M C I T Y C 0 N S U M E R D U C T M A T E R I A L 1. N A Duct Unsea t ed Ductwork l None Sea ed Ductwork I Unse1led D1,1Ctwork 6273 6356 20465 20435 4962 4961 17.55 17.53 z.so 188.0 1 90 . 5 1 ;; .6 15 . 9 160.0 TABLE 9 Operating Cost Parametric Study for Seattle and Galvanized Ductwork Operating Cost Multiplier fOCMJ Sealing Cost__ ($/m2) Not Sealed 1 3 5 7 9 LCC LCC LCC LCC LCC $ $ % % % - % $ % $ % 8 2 2 3__o 1 1 957 0 1 5 69 1 0 1 9425 0 2 3 1 59 0 .00 7988 2.9 1 1418 4.5 1 4848 5.4 1 8 278 5.9 2 1 708 0 _,_ 6.3 0 . 50 8082 1 .7 1 1 51 2 1 4942 4.8 1 83 7 2 5.4 2 1 802 5.9 1 .00 1 1 600 3.7 -8 1 76 0.6 2.9 1 503lr 4.2 i"B1r66 4.9 21896 5.5 1 . 50 8 270 1 1 700 2.1 1 5 1 30 3.6 1 8 5 60 4.5 2 1 990 5.0 2 .QQ__ 8364- �7 1 1 194_ ---1. 4 1 5224 __3_._0 18654 4.0 22084 2.50 8458 1 1 8 88 1 53 1 8 2.4 1 8 748 3.5 221 78 Seattle: -0.6 -2.9 0.6 4 . 12..._ _ 4.2 1 .89 $/kWh Galvanized Ductwork: 33.36 $/m2 TABLE 1 0 Operating Cost Parametric Study for Seattle and Stainless Ductwork - - - LC-C $ Not Sealed 2 5 3 96 0 .00 24777 0.50 % - % - LCC {%1 % 9 -- LCC $ - % -LCC $ - % 0 65084 0 5 1 645 6.4 6060 1 6.9 5.5 5 1 724 6.2 60680 6.8 �2848 5.3 5 1 804 6. , - 60760- 3.8 42927 5., 5 1 8 83 5.9 60839 6.5 34050 3.6 43006 4.9 5 1 962 5.6 609 1 8 6.4 3 4 1 30 3.4 43086 4.8 5 2042 5.7 60998 6.3 353 1 8 0 2.4 33733 4.5 42689 5.6 248 5 6 2.1 3 38 1 2 4.3 42768 1 .00 24936 , .8 33892 4.0 , . 50 2 50 1 5 1 .5 33971 2 . 00 2 5094 1 .2 2 . 50 2 5 1 74 0.9 0 - 7 5 LGG $ - Operating Cost Multiplier (OCMJ 3 , Sealing Cost f$/m2) - 45240 0 5 5 1 62 6.6 - Seattle: 1 .89 $ /kWh Stainless Ductwork: 1 27.98 $/m2 14 4182 BACK TO PAGE ONE TAB LE 1 1 Operating Cost Parametric Study for New York City and Galvanized Ductwork Operating Cost Multiplier (OCM) Not LC C 1 Sealing Cost $ ( $/m2.) LCC ($1 3 % $ LCC LCC % % $ L CC 9 7 5 % - % $ % 1 5094 0 2 7 3 64 0 3 9 634 0 5 1 904 0 641 74 0 0.00 1 45 1 1 3.9 25855 5.5 3 7 1 99 6. 1 48543 6.5 59887 6. 7 0.50 1 4644 3.0 25988 5 .0 37332 5.8 48676 6.2 60020 6.5 1 .00 1 4776 2. 1 261 20 4. 5 37464 5.5 48808 6.0 60 1 5 2 6.3 1 . 50 1 4909 1 .2 26253 4. 1 37597 5. 1 48941 5.7 60285 6. 1 2 . 00 1 5041 0.4 26385 3.6 37729 4.8 49073 5.5 604 1 7 5.9 2 65 1 8 3. 1 37862 4. 5 49206 5.2 60550 5.6 Sealed New York City: 1 6 .34 $ /kWh Galvanized Ductwork: 33.36 $/m2. -0.5 1 5 1 74 2.50 TAB LE 1 2 Operating Cost Parametric Study for New York City and Stainless Ductwork Operating Cost Multiplier (OCMI Cost $ 1$/m2.I LCC % Not Sealed 34966 0.00 34 1 38 2 .4 0.50 34240 1 .00 0 LCC $ 525 1 4 ($) LCC 5 % $ 9 7 % LCC $ . % % 0 98898 6.0 5.5 99000 5.9 8 29 1 2 5.4 9 9 1 0_2 5.8 4.6 8 30 1 3 5.2 9 9 203 5.7 66925 4.5 831 1 5 5.1 9 9 305 5.6 67027 4.3 8 32 1 7 5 .0 99407 5.5 876 1 0 0 70062 50328 4.2 66 5 1 8 5. 1 82708 5.6 2. 1 50430 4.0 66620 4.9 828 1 0 34342 1 .8 50532 3.8 66722 4.8 1 . 50 34443 1 .5 50633 3.6 66823 2 . 00 34545 1 .2 50735 3.4 2.50 34647 0.9 50837 3.2 New York City: $ LCC 1 05 1 58 0 o . 1 6.34 $/kWh Stainless Ductwork: 4 1 82 3 1 Sealing - 1 27.98 $/m2 15