Transcript
A project of Volunteers
in Asia
Guidelines on Evaluatinu Impruved Cookstoves by: Aprovecho
the Fuel
Institute
Published by: United States Agency for Development Washington, DC USA Available from: Aprovecho Institute 442 Monroe Street Eugene, OR 97402 Reproduced Institute.
ConsumptFQn of
by permission
International
USA of the Aprovecho
Reproduction of this microfiche document form is subject to the same restrictions of the original document.
in any as those
l
The information
contained
specifically
at the request
in assessing
fuel
development with
savings
efficient
are all
cookstoves
Until
in a confusion under
must then whole
in Africa. health
looking
to reduce
on calculating of different
laboratory
process
over
the world
and people
concerned
at the potential
for
on how to assess
fuel
more
needs.
"efficiencies",
ways.
Usually
which these
and present
traditional
is complicated
officials
available
conditions
be compared with
of IJSAID, to be used
all
carefully
fuel
by Aprovecho
Bureau
However,
now, the few references
have concentrated
place
of tha Africa
foresters,
planners,
deforestation
here was assembled
and replete
can be defined
measurements
percentage
cooking
take
figures
which The
"efficiencies".
with
use
opportunities
for
error J
and misunderstanding. The methods information cated
described
at a household
apparatus
and evaluating
here level,
the amount of fuel
the process
in village What is
or calculations.
The information
simplify
or city, involved
of collecting without
is simply
can be used several
ways:
To project an overall saved if stoves were whole region.
2.
To calculate the reduced need for imported fuel example) given a widespread program of improved
3.
To examine Beneficial
5.
Foresters -plantings
comparing
used.
1.
4.
compli-
measurement of how much fuel could be to be introduced, for a village or a
the effect of specific design changes changes can then be encouraged. planning woodlots needed to supply
To assess the cost/benefit of fuel saved.
can better fuelwood.
calculate
of improved
stove
(kerosene, stoves. on fuel the size
projects
for use. of
in terms
ii
HOW TO USE THE INFORMATION IN THIS MANUAL .
Some very by stoves
important
may come out
information of this
study.
not
directly
This
relating
to fuel
use
includes:
*
methods that cooks use to conserve fuel which are independent of specific stove use. For example, changes in firebuildinq techniques (using kerosene to-get the fire started quickiy), preheating water in the sun, changes in cooking styles (quick frying rather than long boiling, cooking with retained heat or switching to food which require less cooking time).
*
It is use of non-traditional fuels in improved cookstoves. important to consider the implications of a switch in fuels. Is the new fuel something for which there is no other use in the For example, are people using coconut husks which area? previously were left to rot? Or will switching to a new fuel have serious consequences? Two examples: 1) Burning dung can create a severe problem of decreased soil fertility. 2) Cooking on charcoal accelerates the rate of deforestation, due to inefficiencies of charcoal production methods as well as the use of inefficient charcoal stoves.
Note:
It is possible that this research will show that improved stoves are not saving a significant amount of fuel. This does not mean, however, that stoves may not be serving other useful purposes such as eliminating smoke from the kitchen and thereby having a beneficial effect on the cook's health. This may be a strong enough reason to continue a stove program even though its fuel saving aims are not being met.
For thousands In recent
food.
of years years
traditional
cooking
"improved"
cookstoves.
rural
a firewood
practices.
conversations
quantitative
Included
*
a listing
*
procedures
*
a list
*
the range
*
a few cautions
with
for
introduction
fuel
both savings
urban
of and
resulting
which
begins
with
conducting
the evaluation.
and simple
measurelUi ;.
more information
3f the
is needed
controlled
description
about
fuel
simple
conditions.
of the evaluation
use.
needed and sample
questions.
necessary. results.
to be alert
to.
into
three
sections.
the most information builds
the simplest
described
and fuel
use measurements.
information
give
cooking
of information
is divided
with
they
are
are made under
cooks
Each section
investigation
If
used.
of probablp
if more detailed
together
and those
of the kinds
in which
start
there
by observations
of equipment
the order
is the
from
are:
how to talk
The manual
changes
and observing
is a process
is a step-by-step
*
users
cooks
and fuel
manual
process.
effort.
whether
measurements
This
with
of cookstoves
followed
amounts of food
has prompted
stoves.
between
is then
have been used to cook
One such change
cooks we can evaluate
The evaluation
methods
shortage
By talking
from the use of these
This
open fire
vary
can be obtained
on the previous techniques is required. in what
a good overall
They are presented
they
picture
one.
It
for is
The three can tell of
fuel
methods you,
the least
suggested
and pass on to later
but
consumption.
in
that
sections of used
2
READ THIS FIRST
.
Talking
with
cooks can tell
*
whether
*
the degree are using.
*
changes cooks have made in fuel type, amount used, techniques, and other cooking and fuel consumption
*
the cooks'
*
innovations
T
whether freedom
Talking *
fuel
being
saved or not,
of awareness
concerns
people
about
in stove
and the approximate
savings.
have of the amount of fuel
cooks
fuel.
designs
amounts
cannot
tell
of fuel
they
fire building changes.
or methods
of operating
them.
people perceive other benefits from cookstoves, from smoke, convenience and safety, etc.
with
exact
is
you:
such as
you:
I
used or saved.
PLE HOUS Simple
household
measurements
you:
you can isolate
fuel
*
with
*
with other methods you can tell how much total fuel cooking, heating, lighting, water heating, etc.
*
through comparison much fuel, if any,
Simple
some methods
can tell
household
*
heat
*
the effect‘of
*
the effect
cannot
efficiencies moisture
of individual
tell
only.
is used for
tests these measurements can tell improved cookstoves are saving.
measurements
utilization
use due to cooking
you how
you:
or burn
rates.
content. innovation
in stove
design.
D VARIABL Isolated
variable
tests
can tell
*
the amount of fuel
a stove
*
the effect
*
which fuel.
of changing
adaptations
should
you: uses to cook a typical
a stove
design
be discouraged
meal.
or operating because
it they
differently. use more
READ THIS FIRST
Isolated
variable
*
the real traditional
*
amounts
There
of fuel
tell
you:
lighting, that
heating, the
consumption
for
for
another
purpose,
for
other
either
improved
used or saved in actual
are two ways to calculate
is possible
to sit
cannot
reasons why cooks select means of cooking.
use (cooking, It
tests
cooking for
uses may vary
fuel
etc.)
introduction
savings,
one for
and the other
for
but cause a slight
seasonally,
(see
especially
total
cooking
may decrease
increase
heating
or
use.
of a stove
example,
stoves
only.
fuel
in the amount used
Figure for
fuel
1).
heating
Fuel needs or a fire
around.
33FORE
f
AFTER
I-‘---/OOOON~“’
~-~----%oL$gs$m4
I 60 I H
FIGURE 1 Total all
fuel
savings
will
be calculated
uses of
fuel
(H over
G) whereas
can be calculated Note:
HWSEM’LD USES OF fuEL
from
figures
for
taking the
fuel
cooking
into
account
measures
saved in cooking only
(B over
It cannot be assumed that an improved cookstove same amount of fuel in places or under conditions where it is tested.
of
alone
A). will save the other than
4
READ THIS FIRST
Successful
evaluation
dependent
on how well
Selecting
the best
of the whole
the third
the
performance
can work with
may be the single
is
largely
local most
people.
important
part
process. will
described method,
be responsible
in
this
isolated
Characteristics
manual.
for
work
They may also
variable
tests.
for
in evaluators:
to look
in at least
the
in
Do they have genuine rapport with local people? educated people in poorer countries have little for the poorer people they work with.
*
Do they live in the area or are they familiar with it? Someone who lives there has fewer barriers to overcome.
*
Are they friendly other people?
*
Are they willing to learn from others, who may be from rural areas or different qualities
that
people
and open to new experiences,
will
first
be involved
*
Other
Many respect
ideas
especially income
and
those groups?
help:
*
Older
*
The cooks, comfortable
*
Someone who knows the local language will be most useful. Quite often women do not qet the opportunity to learn other languages; therefore it will be necessary for the evaluator to possess at least a working knowledge of the local language.
In many places carry
out
with
local
local
evaluator
evaluators
The evaluators two methods
of cookstove
are often
it
may be advisable
women and talk
the evaluation.
more respect
than younger
who are nearly always women, will talking with other women, rather
the evaluation.
community
given
leaders
In this with
and seek to gain
often be more than to men.
to use a man/woman team to
team the woman would
the cooks.
ones.
The man would support
make contacts meet with
of the connnunity
the for
READ THIS FIRST
At the local
start
community
or village
Enlist
procedures.
supplies
people
their
about
cooperation
the evaluation
to ensure
talkewith goals
and
good relations
to talk
with
with
about
fuel .
who can supply
good background
information
fuel merchants and on supplies
*
stove vendors cookstoves.
*
women sellinq prepared foods at the market can tell you about the amount of fuel they use and its cost to them
*
cooks in small eatinq establishments information on fuel use
*
older women can tell you about changes in kinds and availability of fuels and changes in food and cooking practices. Fuels currently used may be new ones because the traditionally preferred fuels are no longer available. Cooks may be cooking differently now from how they cooked even a few years ago. is
important tribal
From this
wide
representative
on fuels
and cooking
purpose
choose
The evaluator background
information
can give information on trends of various kinds of fuel.
include:
*
from different
this
leaders
in each area
and use.
Other
find
program
Ask them to recommend people
the community.
It
of the evaluation
may tell
to talk
with
you about
a wide
affiliations range
the
people should
gathered.
in
provide
of women, for
evaluator
cooking
who are cooperative, keep clear
buying
example
groups.
be willing
and to be observed
preference
may also
variety
or income
of contacts
cooks who would
people's
in fuel
and accurate
should
to talk in their interested notes
be able
to
at more length homes.
For
and reliable. on all
the
6
There to watch whether
are good reasons
how they they
techniques.
i
cook in their
are changinq Secondly,
opportunity
to watch
innovations
in fire
best
way to learn
stove
affect
animals
their
these
building about
safer
or rodents
30 different
among those households
where it
in the more detailed
times
about
of fuel
together
give
and look
status?
toward
fuel
of all,
savings
and
most cooks
know
use or cooking the evaluators out
for
this
new cookstoves.
Does it
is
and the
Does the
make the kitchen
Is it
the
subtleties
Finally,
and maintenance.
now possible
air
cleaner?
to keep domestic
of the cook pot? reliable
households. improved
should
First
patterns
from burns?
out
cooks
homes.
attitudes
To get statistically least
with
the cook working
a woman's
Are the children
to talk
results Choose
cookstoves
be possible measurements
talk
with
the households
people
as outlined
from at
at random from
From among these
are used.
to find
cooks
willing
30
to participate
in Section
II.
rtal *
When introducing yourself make your purpose how the information she gives will be used.
clear
and tell
the cook
*
Be friendly and interested but respect the cook's definitions of that you should stay to one space; for example, she may indicate side of the kitchen when she is cooking.
*
Although the discussion will be centered on traditional do not ignore other interests and improved cookstoves, The conversation should be directed the cook feels. questions, but not limited by them.
hearths and concerns by your
TALKING WITH COOKS ABOUT FUEL USE AND COOKING
.
Be sure you know your questions very well. Use the questions as part of a conversation; do not read them word for word from a This improves the flow of the conversation and puts both list. you and the cook at ease. Express your ignorance of cooking practices. the cook to show you how she cooks a typical fuel she uses and whether it correlates with uses.
For instance, ask meal. Note how much what she says she
Use your hands. If you and the cook are talking wood, ask her to show you how big it is with her Is it this big, or this big? hands when asking: tells you she used the cookstove earlier in the If not, are there warm ashes see if it is warm. She may be saying traditional cooking fire is? so as not to disappoint even though she doesn't,
about a bundle of Use your hands. If the cook day, feel it to where her she uses the stove you.
This will ensure that you have Cross check your information. reliable information. Ask questions in different ways; ask contradictory questions; watch everything closely and compare Use two methods if you can. Talk not only with what is said. with the cook but also to the person who gathers or buys fuel. Talk with other people in the household, both male and female, children and adults. Keep clear and accurate to take notes. If it the interview is over you are not permitted short and more frequent, immediately after you During ways.
these
you will
One of the easiest
something:
Could
What kinds
of fuel
can also
be very
many do you burn tive
talks
questions
actions.
notes. First, ask each cook i,f it is OK is OK, take copious notes and as soon as review them and fill in blank spaces. If to take notes, make the interview sessions writing up the information from memory finish talking with the cook. be asking
ways to begin
questions
is to ask the cook to describe
you show me how you build do you burn specific:
in your
How big
to make breakfast?
with
words,
in many different
stove?
a fire
in your
Descriptive
are the sticks
stove? questions
you burn?
The cook may answer
or she may show you the answer
these
How descrip-
through
her
8
TALKING WITH COOKS ABOUT FUEL USE AND COOKING
Another does cooking
It
technique with
is
to ask the cook to make a comparison:
dung differ
from using
The cook may use words
in new ways,
is more important
hear and record
to understand
what
her own words
she says.
when phrasing
what It
is
wood.
stove
Are those
but you just straw
helpful
also
considered
(number
of people
same?
to just you use
to understand
You said
of straw
the
are new to you.
to the cook if In order
bundles
bundles
that
they
the cook means than
she means:
put
How are
or words
the questions.
her words you may have to ask what wood in your
wood?
How
you only
in with
used
that
wood?
Information *
Size
of household
*
Who does the cooking?
*
Is the cooking
*
How many cooking hearths are used? Note types of hearths, traditional stoves or improved stoves. Make a scale drawing the stove is not standard. of chimney
What type
does the
*
Types and average with the season.
*
Number of pots lids used with
*
The type length.
*
Fire
*
If not, Is the stove purchased as a unit? stove or hearth constructed? By the cook, an artisan?
*
Who is responsible
of
stove foods
Materials, used. the pots?
and amount of fuel
regu larly). family?
or out?
*
amounts
there
more than one cook in the
Is there
done indoors
eating
used.
have? cooked
depth
Height
of chimney.
and whether
and diameters
Include
fuel
if
they
vary
of pots.
sizes,
diameter
Are and
and smoke observations.
for
the maintenance
by whom and how is the the man of the family,
and repair
of the stove?
TALKING WITH COOKS ABOUT FUEL USE AND COOKIN;
*
How long improved
ha;e you been using stove)?
your
*
How do you cook on this
*
Do you still use your (name of traditional How often and for what foods, or occasions?
*
Do you make the fire differently in your improved stove than your traditional hearth or stove? How is the fire different? Can you show me? Do you tend or maintain it differently?
*
Do you use the same kind of fuel kinds of fuel now? What kinds? firewood? Bigger? Smaller?
*
Does your new stove method of cooking?
*
Do you collect your own wood? If not, who does? How often must, it be collected? Every day, every other day, twice a week? How much each time? How far do you go? Where do you get it?
*
Do you buy wood? How much does it cost you each time? How often do you buy it now? How often before you had this stove?
*
How long does a (use standard measurement for the area: cartload, bundle, number of sticks, certain amount's worth) of wood last in cooking on your new stove ? How long did the same amount last with the traditional method of cooking?
*
Do you use other
*
If you could change for you, what would
stove?
stove
Will
(use
local
you please
name of
show me?
hearth
or stove)?
: in
as before? Do you use different Do you use the same sizes of
use more or less fuel than your traditional How much do you use now? How much before?
methods
for
conserving
wood?
Please
your stove in some way to make it you change?
show me. work
better
10
TALKING WITH COOKS ABOUT FUEL USE AND COOKING
For doing cooking
isolated
variable
This
profile.
tests
profile
only,
construct
a typical
local
includes:
*
a description
*
the amount of food
*
the kinds used.
*
a description of any other heating; etc.).
fuel
*
the average
which
*
a standard cookins timeline showing the progression of how food cooked, for how long and over what heat, for morning, noon and evening meals.
of a typical
of pots
being
day's cooked
used for
amount of fuel
use of the cookstove. at each meal.
each typical
meal and whether
use (heating, is
used for
1 ighting,
lids
are
water
each task. is
Sample timeline:
FIGIJRE 2 Do a number of sample
timelines
different
you feel
cooks until which
occur
during
for
typical
meals
with
you have a good average.
events
coming
to a boil
Note:
It is important to stay in contact with people who have been especially helpful. Let them know the results of this evaluation and pass on to them any fuel-saving tips you may have Comment on things they have taught you. learned in the process.
sauce
boiling,
lighting
They should
define
and simmering,
cooking:
several
the fire,
rice
etc.
11
Several by improved measure
methods
used.
fuel
cooked,
which
that
use due to the content
through
averaging.
uses improved
cookstoves
adapted
saved
significant
moisture
can be locally
fuel
a statistically
in fuel
can be minimized
Each community methods
gives
Differences
amount of food
construction
are four
can be used to determine
Each method
stoves.
of fuel
performance, stove
different
cook's
in the
fuel,
is unique.
to measure
and
Here
the amount of
saved:
*
SINGLE MEAL MEASUREMENTS
*
COST COMPARISONS
*
WOODSTACKMEASUREMENTS
*
MODIFIED KAYA TEST
WHAT SIMPLE HOUSEHOLDMEASUREMENTSCAN TELL YOU: *
with
*
with other methods you can tell how much fuel is used for cooking, heating, lighting, water heating, etc., combined.
*
some methods
through comparison much fuel (if any) In measuring
dry
weight
difference
fuel
you can isolate
consumption
woods is
their
it not
energy
15% moisture
however,
other
fuels
(charcoal,
Note, peat,
dung)
is necessary its
species
densities
pound most woods have similar content).
use due to cooking
tests these measurements can tell improved cookstoves are saving.
of the wood consumed, between
fuel
(about
to record
but
the
The major pound for
4800 kJ per kg at
the energy
is different.
,
you how
or volume.
or weights,
content that
only
only.
content
of
12
SIMPLE HOUSEHOlD MEASUREMENTS
ingle
easurements
This
is a simple
from improved
a genera 1 idea
way of gaining In these
measurements,
the main meal of the day is weighed
and recorded.
a large idea
cookstoves.
number of both
of relative
fuel
traditional
and improved
of
the
the fue 81 savings fuel
for
Measurements stoves
will
cooking made on
give
a fair
savings.
Requirements: *
a portable
*
an evaluator
scale
that
fluent
measures in the local
to within
10 grams.
language.
Procedure: Find in the community 10 or more improved stove users and an equal number of traditional hearth or stove users who will allow you to make fuel measurements.. Observe each cook in action. Measure the amount of food in pots either by weight or by graduated marks on pot walls. Make measure-' ments of the amount of fuel each cook uses by weighing the fuel before and after the main meal is cooked. Compare the fuel used in the traditional stove to that used in the improved stove. (See Fuel Savings Calculations, page 18.) Thinqs
to be careful
of:
*
be sure the cook is not cooking your presence.
something
special
*
large variations in the size of the households. families of similar average size.
*
small samples which do not represent the population. samples will give more reliable results.
*
be sure that additional that a mixture of fuels charcoal for instance).
*
make sure
*
remember that this used for secondary
because
of
Choose Larger
fuel is not added to the pile, or is not bzg used (wood with dung or -
the cook uses only
one stove
for
each meal.
method will tell you little about fuel meals unless you test them separately.
SIMPLE HOUSEHOLDMEASUREMENTS
.
OS A comparison and improved cities
stoves.
or anywhere
Fuel costs This
will
enables
relative
Cost fuel
is
usually
necessarily
savings
the
traditional
page18.)
Results
and if
fuel
is
of fuel
all
total
rather
fuel
uses,
fuel
savings,
cooking
methods
will sold
for
traditional
are most applicable
purchased,
include
over
are stable
the cost
comparisons
one to assess
Calculations, fuel
can be made between
not
than
collected.
not just
cooking.
not mere y the (see
be more accurate by weight,
in the major
Fuel if
Savings
pr ces for
volume.
Requrrements: *
no special
*
an evaluator
equipment fluent
needed. in the local
language.
Procedure: Conduct a survey in the area to determine which households have improved cookstoves. Randomly choose at least 10 of these households to be the sample population. Ask them to record their fuel purchases for a three month period. Compare these purchases with a randomlv chosen sample of households of comparab e size which use traditional stoves. Thinqs
to be careful in fuel
of:
*
changes
*
Measure a change in the amount of fuel in storage. . . this record it at the beginning and end of survey per1 od.
*
other
*
changes in the types stoves are introduced.
*
make sure cost comparisons may fluctuate seasonally.
fuel
being
prices
used which
is-not
of fuels
being
are over
bought
and
or recorded.
used when improved the same period;
cookcosts
13
14
SIMPLE HOUSEHOLDMEASUREMENTS
In areas quantities, savings.
where wood is collected
woodstack
measurements
These measurements
used for of savings
cooking,
heating
in overall
fuel
seasonally
or bought
in large
can be used to determine
will
indicate
and lighting use after
the total
and will acquiring
fuel
amount of wood
provide improved
a comparison cookstoves.
Requirements: *
a portable scale which nearest 10 grams.
*
an evaluator
who is
is capable
fluent
in the
of measuring local
to the
language.
Procedure: Randomly choose at least 10 families with improved cookstoves of a particular design and a similar number of families without stoves or with traditional stoves. Ask them all to be part of the evaluation and explain its purposes. Weigh the wood in the woodstack after gaining assurance from the cooks that there is more than enough fuel for cooking, heating and lighting during the coming week. Give careful instructions to use only the wood from the stack. Do this on the same day at all 20 houses.
,-.: id
Return periodically throughout the week to check for questions and low fuel supplies. Exactly one week after the start of the test weigh the remaining woodstack. The measurements should be done several times during the year since different fuels and foods might be used.
Alternative
method:
Choose an area where cookstoves are being introduced. Randomly choose A) 10 households without improved stoves, B) 10 with improved stoves, and C) 10 which would like improved stoves. Test A and B simultaneously with C before C get their new stoves. Then test C again after stoves have been built and the cooks are used to using The Fuel Savings Factor between A and B should them. be the same as for C, before, and C, after. If it is very different, you must question your methods.
SIMPLE HOUSEHOLDMEASUREMENTS
An interesting check is to arrange with !3 to cook without their improved stoves, in traditional manner, and record This may tell you whether the action of their fuel use. acquiring an improved stove creates sufficient awareness of fuel economy to actually create a saving. Run all tests for one week. Things
to be careful
of:
*
unweighed
*
other
*
in some areas the daily fuel supply will the woodstack and partially ble collected nearby and placed directly on the fire.
*
differences in moisture content. Check that all fuel for a given house is either straight off the tree or is well.dried; partially dry wood with varying moisture contents can affect the fuel use considerably. Comparisons can only be made between houses using all dry or all green wood. .
types
additions of fuel
to the woodstack which
might
during
the week.
be used. partially off the
come from ground
15
SIMPLE HOUSEHOLDMEASUREMENTS
The Kaya test traditional where only
versus
stoves
improved
cookstoves.
are conducted
are asked
Day 1: Day 2: Day 3:
It
over
day,
is
best
and/or
cookstoves
where
available
use traditional
according
Traditional hearth Improved stove Traditional hearth
to areas
there
for
is
testing.
during
which
time
and improved
to the following or stove ' or stove,
used in
suited
a two week period
to alternately
every.other
the amount of fuel
been introduced
sample of improved
The tests
cookstoves
compares
have recently
a small
the cooks
directly
schedule:
etc.
Requirements: *
a portable
scale
*
test
*
a minimum of five improved cookstove users who are well accustomed to using their stoves and are willing to participate in the test. With fewer than five, statistical accuracy falls rapidly. The cookstoves should all be similar.
evaluators
that
measures
fluent
in the
to the nearest local
10 grams.
language.
Procedure: 1. 2. 3. 4. 5. 6. Note:
Conduct a survey in the area to find improved cookstoves of similar design which can be used for testing. Talk with the users, and determine if they would be willing to be part of a two week test in which they would use both the traditional and the improved stoves. After agreement is reached on their involvement in the test, set aside a sufficient amount of wood to be used for cooking the next day's meals. Record its weight. Ask the cook to use only this fuel in cooking the next day's meals on the traditional stove. Return the following day and weigh the wood that remains. Then weigh out enough wood for use the next day and ask the cook to use it with the improved stove. Continue this testing according to the cooking schedule. A substantial portion of this test "Field Evaluation of Wood Stoves",
was outlined by Cutt February, 1981.
in
SIMPLE HOUSEHOLD MEASUREMENTS
The household will need to be vie zi once each day. During these visits the wood should be ned and the cooks reminded of which stove to use _ the following day's meals. .-._ dsed, the number of people Information on the weight of who ate each meal, the amour af food cooked, significant happenings during the day, ' which stove was used should all be recorded. Any additional helpful observations such as fuel characteristics, fire operation, or unusual weather conditions should also be made. Things
to be careful
the cook us s only
*
be sure
*
in order to assure be acquired by the
Note:
improved
In the tests, a representative
equation:
household
are saving
fuel.
of the amount of fuel
amount used by improved
of stove
was weighed.
total fuel savings or savings If the measured fuel is used etc., then the total fuel If the measured fuel is used measuring the fuel savings due
measurements This
is
to determine
can be done by comparing
used by traditional
stoves
to that
stoves.
measurements sample
wood which
normal amount of usage, the wood should users in the usual manner.
of the simple
cookstoves
measurements
each type
that
This test can measure either due to cookstove use alone. for cooking, heating, lighting, savings are being measured. only for cooking, then it is to cookstove use only.
The purpose if
of:
is
are made under
used to obtain
can be calculated
similar
an average.
according
to the
conditions The average following
and for
17
18
SIMPLE HOUSEHOLDMEASUREMENTS
Average Amount of Fuel Used by Traditional or = Improved Stove Total The average
from the
at the differences comparison
It
is *
*
two stoves
between
them.
is through
a fuel
Fuel Savings Factor
= 1
important
to note
Number of Tests
can be simply
compared
A more complicated
savings
by looking
but useful
way of
factor:
that:
. The fuel savings factor can be calculated in two ways. Total fuel savings is different from that for cooking alone. Total fuel savings are being calculated when measurements are made of total fuel use. Fuel savings from cooking alone are being calculated when only the fuel for cooking is measured. (See Figure 1.) Larger samples give more reliable results. The number of people we have suggested should be considered to be a minimum sample size,. If the results seem inconsistent, use a larger sample size. A more detailed statistical analysis, though not required, might be helpful. (See Appendix A.) From experience
should lower
expect figures
you find efficient
of
improved
stoves
fuel
savings
of between
might
lead
you to examine
no error
in your
or unusually
methods,
inefficient.
already
tested
20 and SO percent.
the
your stoves
evaluation are either
Find out why.
in Africa, Higher methods.
you or If
exceptionally
19
Fuel savings
due to changes
can be determined
by using
provide
a quantitative
typical
meal.
single
design
be used only
measure
modification
for
stove
variable
design
by testing
ideas,
most of which
develop
will
a stove
from
improvements,
speeds
used.
Because
tests
the
the evolutionary new stove
come from the local
adapted
for
how much a
should
projection
of
field.
and evaluating
uniquely
used to cook a
these
not
conditions
These tests
them can tell
not be replicable
testing
should
tests.
the amount of fuel
can be saved in the
Isolated
or operating
of the amount of fuel gained
design
design
variable
changes
conditions
how much fuel
stove
isolated
The information
many household
in stove
to local
process
ideas. people,
cooking
of
These design will
and fuel
help conditions.
WHAT ISOLATED VARIABLE TESTS CAN TELL YOU: *
the amount of fuel
*
the effect
*
which fuel.
of changing
adaptations
The purpose develop
a design
quality
which
in the area. conditions
a stove
will
which
a stove
should
of testinq
stoves
conserves
improve
is
important
design
under fuel
meal.
or operating
be discouraged
because
controlled
it they
as relevant
of the
differently. use more
conditions
or has some other
the likelihood
To make the test it
uses to cook a typical
desirable
cookstove
as possible
is to
being
used
to local
to:
*
use cooks who are experienced
in cooking
local
foods.
*
maintain environmental conditions which are similar to those in households; for instance, don't test outdoors if cooking is done inside, or don't test with pot lids on if people seldom use them.
20
ISOLATED VARIABLE TESTS
Only one variable should
can be tested
be minimized.
dardizing
these
Special
at a time.
attention
All
should
other
be given
differences
to stan-
things:
*
The Cook:
her cooking operations,
*
The Fuel:
its
*
The Cookinq
*
The Stove
Construction:
*
Weather:
especially
behavior, the sequence of cooking and how she stokes the fire.
species,
Pots:
size,
their
and moisture
content.
materials
and size.
shape, its
materials
the effect
and design.
of wind.
The Orqanization Testing These test
improved centers
used,
and where
should
be close
weather,
that
of fuel Local
offer
place
in
accessible
environmental
should
be employed
would duration
use.
will
are
public.
They
altitude, to local
Be sure
as much as possible
As the community identify
the
of the test.
and consulted
of stoves.
the people
the stoves
that
be similar
centers.
come from the same sources
in the community
and testing
n the program
will
the
test
to the general
used should
for
where
to insure
factors
can be maintained
in regional
the areas
to the communities
household
people
take
be located
are readily
enough
in the construction involved
should
The food and fuel
a typical
supply
should
they
and other
conditions.
stoves
with
becomes
the stoves
and
des gn ideas. Cook ng tests
community several
should
be conducted
who are experienced cooks
participate
by two or three
in the cooking
in the tests
will
of local eliminate
women from the foods. differences
Having in
ISOLATED VARIABLE TESTS
cooking
styles
is cooked. offering
and provide
As a group, suggestions
How to do an Isolated The isolated practiced needed
stove.
design
Variable
Test
test
in the local
main meals
needed
Stove; Building
for
which
materials,
are tested design
one variable
being
tests
be cnnducted
Test
#l:
should faults,
of local
and unmodified
should
cooking
as
on a modified
timelines
versus
an
(see page 10).
meals
are cooked
in sequence
be made of the average
amount
cooking.
idiosyncracies
modified
woman in
The amount of fuel
is measured
can then
a lone
approximate
community.
cooking
of when the food
procedures.
closely
and secondary
A comparison
on each stove.
than
and testing
should
meal
measure
be stronger
Use standard
identical
of fuel
will
in stove
to cook a standard
Several
other
they
variable
by people
unmodified
a more consistent
tested.
be identical defects
stoves
stoves
according
be copied
differ
In order
only
to assure to the
and any
carefully.
The
respect
to the
with
similarity
following
of results,
schedule:
Test modified stove. Gain familiarity Do not use results in the analysis.
with
Tests
#2,4,6:
Test traditional or unmodified sequence for the main meal.
Tests
#3,5,7:
Test modified main meal.
Tests
#8,10:
Test traditional or unmodified stove. sequence for the secondary meal.
Tests
tg,ll:
Test modified stove. secondary meal.
stove.
used locally.
in construction,
should
should
to those
stove.
Use cooking
Use cooking
its
operation.
Use.cooking
sequence
for
the
Use cooking
sequence
for
the
21
22
ISOLATED VARIABLE TESTS
Requirements: *
an area
protected
*
a scale
which
*
building
*
several
from rain
measures
materials cooks
and wind.
to the
nearest
and equipment
for
who are experienced
1 gram. stove
in cooking
construction. local
foods.
Procedure: Weigh fuel at the beginning of the test. Start fire using the method which is used in the area. Record the starting time. As events happen record the time they occur. Cook the meal according to the timeline to approximate local cooking. When the cooks decide that the food is cooked ' weigh the fuel that remains. Throughout the test write down comments about the ease of operation, smoke, and tending. amount of fire
Cautions
and Comments:
*
All
testing
should
*
Checks should be made to see if the cooks are burning an excess Correlate the amount of fuel being used by the amount of fuel. cooks with that which is used in typical cooking in the community.
*
Additional data.
*
Use lids
tests on pots
be done on a cold
should only
be run if if
they
stove.
large
variations
are regularly
occur
in
used in the area.
the
DM A
You can determine if the fuel consumed by traditional and improved stoves is significantly different by comparing confidence intervals. A confidence interval is a projection from the fuel use measurements of the range within which the average for the total sample wi 11 fall. This interval is directly dependent upon the degree of confidence you choose, the number of measurements made, and the amount of variabi 1 ity in the measurements. Steps 1)
in
Solvinq
Calculate
for the
the) Confidence
Average,
x,
for
Interval the
+ kas;;,,,r) Total 2)
Calculate
the
s.d.=.
a)
+ kas;yment)+
number
Standard
sample.
of
Deviation,
measurements
.....,..... made,
n
s.d.
/I
The caculation using a table.
of
Column
the
standard
c01ulltn
1
Measurements from a single Jseries of tests,
is
most
2
X2 x
(Measurement + (Measurement
#l )
(Measurknt + . .
#3)
Total sum of al 1 measurements
deviation
#2)
(Measurement + (Measurement (Measureknt + . .
#1)2 #Z) 2
#3)2
Total sum of a 11 measurements squared
easily
done
by
23
24
APPENDIX A
b)
Now, substitute Standard Deviation
3)
Determine
4)
Choose result.
b)
Look
Calculate
T-
the
equation:
=
the
a)
into
t-distribution
factor,&G,
in
the
the
table
and
Confidence
t+) (s.d.)
find
the
to be careful
distribution
table. the
factor,,&.
Interval <
TT
