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close this book Boiling Point No. 02 - May 1982
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View the document Firewood Consumption Survey in Sri Lanka

Firewood Consumption Survey in Sri Lanka

As part of ITDG's programme to develop suitable field testing procedures, Jan Bialy surveyed fuelwood consumption in a village in Sri Lanka.

"This survey was carried out at the home of a farming family in a small village near Anuradhapura where the writer had worked three years previously. The cooking place consisted of the common '3-stones' arrangement, made in fact with 6 bricks placed two high as shown in Figure 1.

The quantities of wood used for each cooking operation, the quantities of food cooked and the vessels used were recorded over a period of 23 hours from 1500 hr on Friday, 17th July. The results are presented in Table 1. All weighings were made with a Salter plastic kitchen scale weighing up to 4.5 kg by 25 g divisions. This scale was not really suitable for weighing firewood or heavy ceramic vessels as the reading was particularly sensitive to the positioning of the weight on the pan. Besides, some ceramic vessels, when filled with food, were too heavy to be weighed, so that some of the food had to be removed and weighed separately. A spring balance would have been more suitable and would have lessened the disturbance to the cook. The full co-operation of the family is essential in making a survey of this kind and every effort must be made to minimise the inconvenience caused in carrying out the necessary measurements. It is very easy to forget to use wood only from the measured pile, or to add wood to the pile without informing the researcher. It is necessary for the researcher to be present in the kitchen the whole time, because the fire is frequently used outside the normal cooking times for minor operations like boiling water for tea, reheating tea, roasting chillis prior to grinding them or boiling buffalo milk to make curd.

The summarized results on the survey given in Table 2 (6.4) reveal that about 20% of the total weight of wood burnt was not in fact used for any cooking operation, but was consumed when the fire was shouldering between operations. The quantity of wood consumed when the fire was burning without any vessel on top came to only 1% of total weight used, but it is likely that if the writer had not been making measurements, the quantity consumed in this way would have been higher. It is worth noting that changing the design of the stove would probably have little effect on the quantity of wood lost in smouldering, in this case 1.3 kg a day.


FIGURE

Of the quantity of wood used for cooking, that is 5.3 kg in the day, 60% was used for cooking the rice and curry for lunch and dinner, and almost a quarter was used in boiling water for tea and reheating tea. It has been suggested that information about the quantities of wood used for different cooking operations could be obtained by measuring the duration of each operation and by assuming an approximately constant burning rate. Unfortunately, the burning rate does vary in some operations such as cooking rice, because the rice is usually allowed to simmer for some time on the remains of the fire after the flames have been put out. Thus it can be seen from the second half of Table 2 that of the total time spent cooking, the cooking of the main meals (rice and curry) accounted for only 45% (compared to 60% of the total weight of wood used for cooking). Similarly, because the fire used for making tea is generally smaller than that used for cooking food, the percentage of the total time spent cooking which is devoted to making tea is over 30%.

Exerpt from report by J. Bialy


FIGURE