in collaboration with Jimma Institute of Technology,

Public Health Institute (PHI) and Population Health and Environment (PHE)

(Draft Report)

By: Ethio Resource Group Email: erg@ergethiopia.com

www.ergethiopia.com Addis Ababa

April 2015

Evaluation of Baseline and Improved Institutional Cookstoves for kitchen air pollution

and fuel consumption in Jimma University  

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Table of Contents

1   Introduction .................................................................................................................. 2  2   Methods ........................................................................................................................ 4  3   Fuel consumption measurement ................................................................................... 8  4   Indoor Air Pollution (IAP) measurement ..................................................................... 9  

4.1   Results of IAP monitoring .................................... Error! Bookmark not defined.  5   Conclusion .................................................................................................................. 10  References ......................................................................................................................... 11  Annex: Data from cooking test ......................................................................................... 12  

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1 INTRODUCTION According to the World Health Organization, in low-middle income countries 4.3 million people annually die prematurely from exposure to household (indoor) air pollution due to cooking with solid biomass fuels on open hearth1. Cooking situations in social institutions where mass cooking takes place such as universities, hospitals, prisons is the same as in the households. In institutions, intensity of cooking is very high and so is the level of indoor air pollution and fuel consumption. In Ethiopia, household cooking energy problem and its impact on health and the environment is given due emphasis by the government and development partners. Accordingly a National Improved Cookstove Program, which mainly focuses on household cooking problem is under implementation. Problems associated with institutional cooking have not got sufficient attention. This project aims at bringing solutions to institutional cooking problems arise as a result of using solid biomass fuel by piloting clean and energy efficient institutional cookstoves in Jimma University Institute of Technology (JIT). This report is part of the study which aimed at determining the suitability of improved institutional stoves in Ethiopian institutions in terms fuel consumption and household air pollution (HAP) reduction compared to the baseline stove. Improved institutional stoves were introduced to replace the baseline stoves in Jimma Institute of Technology (JIT) in Jimma University for pilot trial to determine their performance and acceptability by the cooks. Fuel consumption measurements and air pollution concentration levels in the kitchen were determined during cooking. The improved stoves were tested cooking same type of food so that results will be comparable with baseline stoves which were tested in similar conditions. The baseline stoves in JIT were three-stone open fire. The improved stoves are known by their brand name “InStove” and were imported for this project. However, local manufacturing is anticipated ones they are proven for institutional cooking in Ethiopia. Description of study location

Place Jimma Institute of Technology, Jimma University, Jimma

Altitude 1772m Goe-reference data 036 48'.52446''E

07 41' 43.973''N Ambient temperature Cloudy Local water boiling temperature 96 oC Rainy season?

JIT uses firewood as primary source of cooking energy. Injera2 is outsourced and hence the institute does not practice baking. While tea is partly prepared on electric stoves, all other foods are prepared with firewood in a kitchen that is not well ventilated. The types

1 http://www.who.int/mediacentre/factsheets/fs292/en/ (Accessed date: 15 November 2014) 2 Injera is a staple food. It is like a pan-cake but thinner and larger in size.

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of stoves used are of two types: enclosed fired brick stoves without chimney and the three stone (Open Fire). The Institute purchases wood from the university’s income generating scheme which owns eucalypts plantation adjacent to the JIT campus. The price has always been lower than the market price3. Figure 1.1: Baseline and Improved Stoves in Use in JIT

InStove comes in two sizes – 60 and 100 liters. It takes two of the 100 liter improved stove to replace one 200 liter size baseline stove. Description of the kitchens and stoves set up The first kitchen was where the baseline stoves were tested. Tin sheets were used to build the roofs and walls. Opening was left between the roof and the walls for ventilation. In this kitchen firewood was used for cooking using open hearth and enclosed stoves. The second kitchen was a nicely built modern facility with a hood system to vent out fumes from cooking. This was meant for electrical cooking appliances which were not yet installed in the kitchen. Improved stoves were tested in both the first and the second kitchen. The chimneys of

3 Average price of firewood in Jimma was ETB 274 per meter cube (or ETB 043 per kg)

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the improved stoves in the first kitchen were simply extended to vent the smoke in the kitchen but above the height of the cooks. The second set of tests with the improved stoves were conducted in the second kitchen. The chimneys of the stoves were vented to the hood system. The reason for conducting the second set of tests with the improved stoves was to avoid background smoke that might possibly contaminate the kitchen from other cooking activities that took place in the adjacent kitchen. 2 METHODS Fuelwood consumption and indoor air pollution (IAP) concentration level were measured during cooking of breakfast, lunch and dinner for three days. Data was taken during the preparation of each meal. The collected data was analyzed to determine the values of cooking performance indicators such as consumption of dry wood equivalent and specific wood consumption.

A. The fuel characteristics Eucalyptus is the species of fuelwood used in all kitchens in the university. Moisture content of the wood were measured on wet basis using digital wood moisture meter. Fuel consumption is compared based on equivalent weight of dry wood consumed. Equivalent dry wood consumed (fd): is used to adjust for the amount of wood that was burned in order to account for the wood that must be burned to vaporize moisture (1.12 is the correction factor) in the wood and the amount of char remaining unburned after the cooking task is completed (1.5 is the conversion factor of charcoal to equivalent amount wood).

𝑓! = 𝑓!× 1− 1.12×𝑀𝐶!" − 1.5×𝑚!!  ……………… (2) (Bailis et al, 2007)

Where: 𝑓! = wood consumed, 𝑀𝐶!" =moisture content (wet basis), 𝑚!! = mass of remaining charcoal

Specific fuel consumption (SFC): is the principal indicator of stove performance that tells the tester the quantity of fuel required to cook a given amount of food for the “standard cooking task”. It is calculated as a ratio of equivalent dry fuel to food cooked multiplied by 1000, read as gram of fuel consumed per kilogram of food cooked.

B. Kitchen Performance Test (KPT) KPT was conducted for three days on each of the baseline and improved stoves. Weight measurements on fuel consumption, amount of food cooked and time taken for cooking were recorded. Three meals were prepared per day whereby two types of food were served in each meal. The first set of tests were conducted on the baseline stoves for three days. A total number of 18 data points were recorded. The second set of tests were conducted to evaluate the performance and emission level of the improved stoves.

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Since the size of the improved stoves and associated cooking pots were half the size of the baseline stoves, the number of tests required to cook equal amount of food was double. Hence, the number of tests conducted with the improved stoves was 36. Before conducting the tests on the improved stoves, preparation of firewood appropriate for the stoves was required as per the instruction of the manufacture of the stoves. This was splitting and drying of firewood. For this, a shed had to be built for stacking and drying firewood. A separate kitchen was also prepared for testing as emission tests required isolation of the test place from any background emission from cooking that was held in parallel in the other kitchen. The second set of tests were conducted about 2 months after the baseline stoves were tested. Test data is presented in the Annex.

C. Indoor Air Pollution (IAP) Monitoring the level of air pollution in a kitchen involves measurement of the level of pollutants, particularly the concentration of carbon monoxide (CO) and fine particulate matters of size less than 2.5 micrometer (PM2.5). Indoor Air Pollution (IAP) as a result of solid biomass burning has been reported as one of the ten most important threats of public health. The World Health Organization (WHO) identified that in 2012 IAP was responsible for more than 4.3 million deaths globally. IAP has been proved as a cause of pneumonia and other acute lower respiratory infections (ALRI) among children of five years of age, chronic obstructive pulmonary diseases (COPD) and lung cancer among adults 4.

In Ethiopia, solid biomass fuels are the main source of cooking energy in households, institutions and businesses. The health impact of IAP in Ethiopia is among the highest in the region. The World Health Organization has evaluated the national burden of disease attributable to solid fuel use in Ethiopia at 4.9% (WHO, 2007).

Table 6 Percent of national burden of disease due to solid fuel burning in selected countries

Country Percent of National burden of disease due to solid fuel burning

Ethiopia 4.9% Kenya 2.9% Malawi 5.2% Rwanda 5.8% Uganda 4.9% (Source: WHO, 2007)

There are numerous methods to reduce the level of indoor air pollution and decrease the associated health risks. These include, improved cooking devices, alternative fuel-

4 WHO, 2007, Indoor Air Pollution: National Burden of Disease Estimates

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cooker combinations, improving ventilation and changing cooking practices5 (Rehfuess, 2006). Proper preparation of the fuel which includes splitting and drying also helps to reduce the level of emissions from burning solid biomass fuels during cooking. The World Health Organization prepared new Indoor Air Quality Guidelines for safe air quality levels. The guidelines indicated the maximum exposure limit to carbon monoxide and particulate matter that are considered safe to human beings. A. Carbon monoxide (CO) Human hemoglobin has high affinity to carbon monoxide which roughly is about 240 times that for oxygen. The health impact of exposure to carbon monoxide is that it impair the oxygen carrying capacity of blood. Depending on the level and duration of exposure to CO, health impacts of concern are cardiovascular, acute pulmonary, cerebrovascular and behavioral effects, and developmental toxicity. The World Health Organization has set recommended values for maximum exposure limit to carbon monoxide level. Level of exposure depends on the duration of exposure.

Table 7. Maximum Time Weighted Average Carbon Monoxide Exposure Limits (WHO)6

Duration of exposure Maximum Exposure limit Parts per million (ppm) gm/m3

15 minutes 87 100 30 minutes 52 60

1 hour 26 30 8 hours 9 10

24 hours 4

For peak exposure limit the National Occupational Safety and Health Administration of the USA recommended 200 ppm7. B. Particulate Matter (PM2.5) Airborne particulate matter of size less than 2.5 micrometer (PM2.5) are of important concern as they may reach lower respiratory system, terminal bronchioles and alveoli. Combustion of solid biomass such as fuelwood and dung is an important source of particulate matters largely in PM2.5 mode. According to the World Health Organization’s Air Quality Guidelines (WHO AQG), exposure limits to PM2.5 over 24 hours is 25 microgram per cubic meter (25µg/m3 or 0.025mg/m3)8. Increased exposure to PM2.5 will

5 Rehfuess, E, 2006, Fuel for Life: Household Energy and Health, Geneva, WHO 6 WHO, 1999. Environmental Health Criteria 213, Carbon Monoxide (Second Edition), Geneva, 1999 7 National Institution for Occupational Safety and Health, 1992. 8 WHO, 2006. Air Quality Guideline for PM, Ozone, nitrogen dioxide and sulfur dioxide, Global update 2005,

Summary of risk assessment.

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make one more susceptible to infection of the lower respiratory system and aggravates any existing respiratory diseases.

Table 8. Maximum mean exposure limit to PM2.5 for 24 hours and annual (WHP, 2006)

Duration PM2.5 24-hour mean 25µg/m3 (or 0.025mg/m3) Annual mean 10µg/m3 (or 0.01mg/m3)

IAP monitoring equipments Data was taken for the duration of six testing days using Lascar Electronics (EL-USB-CO) and UCB PM monitor for the baseline and improved stoves each. For PM monitoring, data was collected every second and averaged for every minute. Carbon monoxide level was read every second and averaged every half a minute. The results were analyzed for Peak and Time Weighted Average (TWA) values for the testing period.

A UCB PM monitor and a Lascar Electronics carbon monoxide logger (EL-USB-CO) were mounted adjacent to each other at a selected point in the kitchen. The mounting locations of the IAP monitors were selected so as to be at a height of about 145 cm above the floor (average breathing height of a standing cook) and at least 150 cm away (horizontally) from open doors as per the guidelines for setting up of the instruments.

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3 FUEL CONSUMPTION MEASUREMENT A. Moisture contents of fuel Use of well dried and split firewood improves combustion and hence help to reduce household air pollution due to burning of solid fuels for cooking. With the introduction of the improved cookstoves, fuel management practice which involved splitting and drying of firewood was introduced. As shown in the figure below, there is significant difference in the moisture content of the firewood used during the baseline and the post assessment with the improved stoves. With splitting and drying practice introduced, it was managed to reduce the moisture content of the fuel by half.

Figure 3.1 Average moisture content of the fuelwood used for testing

B. Daily Fuelwood Consumption Fuel consumption data was collected for the daily cooking for each meal cooked during breakfast, lunch and dinner on each stoves. Data was analyzed to determine the daily, fuel consumption, fuel consumption index and time taken for cooking. Table 3.1: Mean Fuel consumption and time taken for daily cooking

 Parameters       Baseline   Improved   Difference  Total  cooking  time   Hours/day   8.8  (1.3)   7.1  (0.8)   19%  Total  weight  of  fuel  consumed   kg/day   181  (36.4)   42  (1.3)   77%  Specific  fuel  consumption   g/kg   178  (39.6)   23  (2.4)   87%  Standard  deviations  are  in  brackets   The total cooking hour for preparation of breakfast, lunch and dinner is between 7 to 9 hours. The average cooking time with the improved stoves was reduced by about 19%. This was mainly due to better thermal efficiency of the improved stoves which also helped to improve the cooking speed. The improved stoves showed a remarkable fuelwood consumption reduction. The Specific Fuel Consumption (SFC), which is the ratio of the amount of fuelwood consumed to the amount of food cooked, showed that the relative fuelwood reduction with the improved stoves was about 87%.

25.60%  

12.90%  

0.00%  

10.00%  

20.00%  

30.00%  

Baseline  stoves   Improved  stoves  

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4 INDOOR AIR POLLUTION (IAP) MEASUREMENT IAP monitoring included measurement of CO and PM concentration level in the kitchen during preparation of breakfast, lunch and dinner for 72 continuous hours during the three testing days for each of the baseline and improved stoves testing period. Cooking in the kitchen starts early in the morning usually around 5:30 AM or earlier and lasts for seven to ten hours. The three days average emission levels for maximum and mean PM2.5 and CO are shown in the Figures below. Figure 4.1 PM and CO levels during the three days cooking with baseline stove

Figure 4.2 PM and CO levels during the three days cooking with improved stove

As it can be seen in the Figures above, peak emission levels over 160 ppm or mg/m3 for CO and Pm were observed during lighting. This happened during lighting of both baseline and improved stoves even though the duration was shorter for the improved

4:38:00  

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0  10  20  30  40  50  60  70  80  90  100  

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 PM  (m

g/cm

3 )  and

 CO  (P

PM)  

PM2.5  and  CO  levels  during  the  three  days  of  cooking  -­‐  Baseline  stoves  CO  (PPM)   PM  (mg/m3)  

4:30  

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0  10  20  30  40  50  60  70  80  90  100  

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PM2.5  and  CO  levels  during  the  three  days  of  cooking  -­‐  Improved  stoves  

PM  (m

g/m

3 )  and

 CO  (P

PM)  

PM  (mg/m3)   CO  (PPM)  

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stoves. The reduction of household air pollution is clearly seen by comparing the emission levels of the baseline stove in Figure 4.1 and that of improved stoves in Figure 4.2. The three days 24-hour Time Weighted Average (TWA) emissions level for PM2.5 and CO are shown in Table 4.1 below. Table 4.1: Three days 24-hours TWA PM and CO levels of exposure for baseline and improved stoves Stove  type   CO  (PPM)   PM  (mg/m3)  

WHO  standard   4   0.025  Baseline   10.6   4.8  Improved   2.0   1.5  Improved*   2.5   1.1  Difference  b/n  baseline  &  Improved*  (%)   76   77  *Tested  in  cleaner  kitchen  where  there  is  no  background  emission  from  other  parallel  cooking   CO and PM levels were significantly reduced with the improved stoves. CO levels over the 24 hours period was much lower than the maximum allowable exposure level recommended by WHO. With the improved stoves CO and PM levels were reduced by 77% compared to the baseline conditions.

5 CONCLUSION The cooking comparison tests conducted in JIT with the baseline stoves (Three stone open fire) and the improved stoves shows that the improved stoves reduce fuel consumption by about 87%, CO and PM2.5 concentration levels in the kitchen by 77%, and cooking time by 19%. It was also observed that the cooks very much liked the improved stoves for their convenience to cook with. The cooks also commented that the improve stoves help to keep the kitchen clean and hygienic as there was literally no smoke and soot to spoil the food and make running nose and watery eyes. The size of the improved stoves was, however, commented as one of their limitations. The improved stoves come only with 60 and 100 liter sizes while most of the cooking in JIT is with 200 liter pots. Replacement of one baseline stove requires two 100 liter improved stoves. This will have implication on the number of cooks needed. One cook normally works on two baseline stoves. With the improved stoves, one cook needs to work on four stoves or more cooks are required. Despite this limitation, the cooks preferred to work on the improved stoves as cooler and smokeless kitchen helped them maintain their strength throughout the day.

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REFERENCES Baker, A. J., Ragland, K. W. and Aerts, D. J. (1991), “Properties of Wood for

Combustion Analysis”, Bioresource Technology, volume 37, pp.161-168 National Institution for Occupational Safety and Health, 1992.

Parikh, J, Channiwala, S.A. and Ghosal, G.K. (2005), “A correlation for calculating HHV from proximate analysis of solid fuels”, Fuel, volume 84, pp. 487–494

Rehfuess, E, 2006, WHO, Fuel for Life: Household Energy and Health, Geneva Rob Bailis, et al. (2007), Shell Founation Household Energy and Health Program, Water Boiling

Test.

WHO, 1999. Environmental Health Criteria 213, Carbon Monoxide (Second Edition), Geneva, 1999

WHO, 2006. Air Quality Guideline for PM, Ozone, nitrogen dioxide and sulfur dioxide, Global update 2005, Summary of risk assessment.

WHO, 2007, Indoor Air Pollution: National Burden of Disease Estimates

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ANNEX: DATA FROM COOKING TEST A1.1 Baseline stove Date

Unit Day 1 (21-05-2014)

Type of meal Breakfast Lunch Dinner

Food type

Sauce (Alicha Firfir)

Tea Misirwot (Kei)

Misirwot (alicha)

Gomen Batkilt Shiro

Pot type Pot-A Pot-B Pot-B Pot-A Pot-A Pot-A Wood used for pre-heating in another stove kg 0 0 0 10.5 0 0

Initial weight of wood kg 59 58 121 155 94 95.5 Wood moisture content (wet basis) % 26% 26% 23.40% 25.10% 24% 26%

Time fire lit 4:38 AM 4:44 AM 8:30 AM 8:35 AM 12:24 PM 12:24 PM Starting time 4:46 AM 4:48 AM 8:35 AM 8:40 AM 12:36 PM 12:36 PM Additional weight of wood kg 0 0 0 0 0 0 Final measurements Time cooking ended 6:55 AM 6:50 AM 11:15 AM 11:00

AM 3:27 PM 2:59 PM

Weight of wood remaining kg 32 33 92.5 112 51 56 Weight of char remaining kg 4.5 3.75 6 7.5 5 5.5 Empty weight of smaller pot-1 kg 5.8 0 7.9 7.6 6.8 5.3 Weight of smaller pot -1 with food kg 39 185 56 57 52 50 Empty weight of smaller pot-2 kg 6.1 6.8 7.7 6.1 6 Weight of smaller pot -2 with food kg 48 57.5 64 52 45 Empty weight of smaller pot-3 kg 6.4 6.7 7.7 6.5 6.3 Weight of smaller pot -3 with food kg 43 59 56 49 48 Empty weight of smaller pot-4 kg 3.5 3.6 3 5.7 6.7 Weight of smaller pot -4 with food kg 21 33 25 34 44 Amount of food served per student kg 0.2 0.150 0.150 0.125 0.17

Data Analysis Time taken to light the stove min. 8 4 5 5 12 12 Time taken for cooking No 129 122 160 140 171 143 Total weight of wood consumed kg 27 25 28.5 53.5 43 39.5 Equivalent dry weight of wood consumed kg 12.39 12.10 12.03 27.21 23.94 19.75

Total weight of food cooked kg 129.2 185.0 180.5 176.0 161.9 162.7 Specific Fuel Consumption g/kg 95.879 65.378 66.652 154.603 147.879 121.374

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Annex-1 (cont’d) Date

Unit Day 2 (22-05-2014)

Type of meal Breakfast Lunch Dinner

Food type Rice Tea Aterkik (Kei )

Aterkik (Alicha)

Sigawot (Kei)

Sigawot (Alicha)

Pot type Pot-A Pot-A Pot-B Pot-A Pot-A Pot-B

Wood used for pre-heating in another stove kg 0 0 10 10 0 0

Initial weight of wood kg 82 100 74 88 76 75 Wood moisture content (wet basis) % 25% 25% 25% 25% 26.80% 26.80% Time fire lit 7:30 PM 4:52 AM 7:00 AM 7:30 AM 12:48 PM 12:48 PM Starting time 7:35 PM 4:55 AM 7:05 AM 7:35 AM 12:52 PM 12:52 PM Additional weight of wood kg 0 0 0 0 0 0 Final measurements Time cooking ended 8:40 PM 7:25 AM 9:45 AM 9:45 AM 4:13 PM 4:14 PM Weight of wood remaining kg 62 62 40 42 29 34 Weight of char remaining kg 2.8 7 5 4.5 6.5 5.5 Empty weight of smaller pot-1 kg 7 0 5.8 6.7 5.9 6 Weight of smaller pot -1 with food kg 46 185 50 49 56 47 Empty weight of smaller pot-2 kg 6.9 5.5 6.4 5.5 4.4 Weight of smaller pot -2 with food kg 49 45 48 51 47 Empty weight of smaller pot-3 kg 7 5.9 7.3 6 6 Weight of smaller pot -3 with food kg 41 46 49 54 47 Empty weight of smaller pot-4 kg 3.1 8.7 11.7 5.9 5.1 Weight of smaller pot -4 with food kg 10.1 53.3 70 47 48 Amount of food served per student kg 0.15 0.2 0.15 0.15 0.15 0.17 Data Analysis Time taken to light the stove min. 5 3 5 5 4 4 Time taken for cooking No 65 150 160 130 201 202 Total weight of wood consumed kg 20 38 44 56 47 41 *Equivalent dry weight of wood consumed kg 10.20 16.86 24.18 33.57 23.14 20.44

Total weight of food cooked kg 122.1 185.0 168.4 183.9 184.7 167.5 Specific Fuel Consumption (21/20) 83.538 91.135 143.587 182.545 125.298 122.050

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Annex-1 (cont’d) Date

Unit Day 3 (23-05-2014)

Type of meal Breakfast Lunch Dinner

Food type Tea Kinche Aterkik (Kei )

Aterkik (Alicha )

Misirwot (Kei)

Misirwot (alicha)

Pot type Pot-A Pot-B Pot-A Pot-B Pot-B Pot-B

Wood used for pre-heating in another stove kg 0 0 10 10 0 10

Initial weight of wood kg 75 69 71 75 66 86 Wood moisture content (wet basis) % 26.8% 26.8% 26% 26% 27.50% 27.50%

Time fire lit 4:15 AM 9:25 PM 7:33 AM 6:50 AM 12:15 PM 12:30 PM Starting time 4:20 AM 9:30 PM 7:36 AM 7:00 AM 12:50 PM 12:55 PM Additional weight of wood kg 0 0 0 0 0 0 Final measurements Time cooking ended 7:25 AM 11:50 PM 10:00 AM 10:20 AM 4:42 PM 4:42 PM Weight of wood remaining kg 47 56 39 42 35 58 Weight of char remaining kg 4.5 1.25 3.5 2.75 1.75 2.5 Empty weight of smaller pot-1 kg 0 5 6.7 5.7 5.8 7.7 Weight of smaller pot -1 with food kg 185 41 53 50 48 49 Empty weight of smaller pot-2 kg 4.5 5.2 6.2 6.4 8 Weight of smaller pot -2 with food kg 42 54 51 48 54 Empty weight of smaller pot-3 kg 3 6.4 6.2 6.5 8.2 Weight of smaller pot -3 with food kg 20 53 50 48 53 Empty weight of smaller pot-4 kg 2.2 10.2 9.9 5.6 10.5 Weight of smaller pot -4 with food kg 14 71 79 43 67 Ammount of food served per student kg 0.15 0.138 0.15 0.138

Data Analysis Time taken to light the stove min. 5 5 3 10 35 25 Time taken for cooking No 185 140 144 200 232 227 Total weight of wood consumed kg 28 13 42 43 31 38 *Equivalent dry weight of wood consumed kg 12.85 7.22 24.52 26.35 18.83 22.55

Total weight of food cooked kg 185.0 102.3 202.5 202.0 162.7 188.6 Specific Fuel Consumption 69.435 70.605 121.084 130.462 115.716 119.544

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A1.2 Improved stove (First set of tests)

Date

(Day 1) 24-09-2014 Type of meal

Lunch Dinner

Food type

Alicha kik Key Kik Alicha Miser Key Miser Pot type

Empty weight of pot kg 8 8 8 8 8 8 8 8

Initial weight of wood kg 26 26 26 25.5 10.5 10.5 10 10 Wood moisture content (wet basis) % 18% 18% 21% 21% 21% 21% 21% 21%

Time fire lit

7:37 AM

7:49 AM

7:43 AM

7:46 AM

12:37 PM

12:38 PM

12:40 PM

12:39 PM

Starting time

7:41 AM

7:54 AM

7:52 AM

7:52 AM

12:43 PM

12:45 PM

12:47 PM

12:49 PM

Additional weight of wood kg 0 0 0 0 0 0 0 0 Final measurements

Time cooking ended

9:47 AM

10:34 AM

9:47 AM

9:37 AM

3:43 PM

3:26 PM

3:23 PM

3:40 PM

Weight of wood remaining kg 20 21 20 19.5 5 5 3.5 4 Weight of char remaining kg 0.75 0.5 1.5 1 0.25 0.5 0 0.5 Empty weight of smaller pot-1 kg 4.5 3 3.5 3 3.5 3 3.5 3 Weight of smaller pot -1 with food kg 27 25 25 26 25.5 25 27 25 Empty weight of smaller pot-2 kg 3.5 4 3.5 3 3 3.5 3 3.5 Weight of smaller pot -2 with food kg 26 28.5 29.5 27 25.5 26 27 28 Empty weight of smaller pot-3 kg 4.5 3.5 3 3 3 3.5 3.5 3 Weight of smaller pot -3 with food kg 25 24 24 25 24 25.5 24 25 Empty weight of smaller pot-4 kg 3.5 3.5 3 3.5 3 3 3 3 Weight of smaller pot -4 with food kg 25 25 25 19.5 17 13 17.5 17 Ammount of food served per student kg 0.3 0.3 0.3 0.3 0.4 0.4 0.4 0.4 Data Analysis

Time taken to light the stove min. 4 5 9 6 6 7 7 10 Time taken for cooking min. 126 160 115 105 180 161 156 171 Total weight of wood consumed kg 6 5 6 6 5.5 5.5 6.5 6 *Equivalent dry weight of wood

consumed kg 3.65 3.23 2.36 3.11 3.85 3.47 4.99 3.86 Total weight of food cooked kg 87.0 88.5 90.5 85.0 79.5 76.5 82.5 82.5

Specific Fuel Consumption (21/20) g/kg 41.9 36.4 26.0 36.6 48.4 45.4 60.5 46.8