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- because many expenditure categories are covered, the level of d:tail is unsatisfactory, often, importnt variables such as price, fuel availability and end-use equipment are not included;

- typically, no time series data are generated by these exercises because they are undertaken infrequently and/or do not use the same methodology, including questions, for each iteration; and

- because these surveys mostly concentrate on cash purchases, collected fuels (wood, twigs, agricultural and animal residues) are not reflected in final consumption figures.

Still, there is room for improvement whereby t i- hehold energy module can be incorporated in the family budget survey to generate useful information for pi ning and implemenitation purposes An example<sup>of such</sup> a module, which was added to the 1987-88 Family Budget Survcy in the Yemen Arab Republic, is<sup>presented in</sup> Annex 1.

# Micro-survy

These data collection ex'rcises are aimed at understanding the social and microeconomic aspects<sup>of</sup> household energy demand in a limited geographical area. Generally, they can involve a sample of up to<sup>several</sup> hundred households, may cover several villages and could rely on re-surveying. They are attractive because: (a) micro-surveys are usually inexpensive; (b) because of their small sample size, they can be undertaken and analyzed relatively rapidly, and (c) because of their smali size and limited geographical focus, they are easily managed. On the negative side,

- their specific focus is also a limitation as one can rarely extrapolate results from the sample to the national, or even regional, population;

- in practice, they often don't measure such important characteristics as efficiency of end-use devices, the natural resource stock and income or expenditure level; and

- they are one-shot affairs which don't allow for comparison of results over time, especially regarding seasonality of fuel use.

So, micro-surveys are generally not appropriate for yielding a database that will allow for understanding and addressing energy problems at the national level. If carefully designed, they can be useful for assessing the situation in a pre-defined area and, as such, may have important applications in regions which have special problems.

# Additional Techniques for GQthering Specific Household Energy Information

Specialized investigatory techniques can be used to get important, detailed information on particular<sup>subjects,</sup> e.g. cooking efficiency, household decisionmaking and precise biomass fuel consumption. Laboratory and<sup>field</sup> tests should be conducted to determine theoretical and actual energy efficiencies of cookstoves and ovens.<sup>This</sup> will be essential for calculating the cost of useful energy in cooking. Sociological studies can be made<sup>to</sup> document how family decisionmaking occurs regarding inter alia purchase of fuel, ccioking practices and procurement of cooking equipment. For fuel consumption, a small, representative sample of households<sup>can be</sup> chosen for intensive investigation. Surveyors can visit residences on a daily basis over a period of several weeks to determine exact amounts of fuel used through weighing, volumetric measurements and detailed questioning. For example, FAO has been undertaking countrywide wood consumption surveys since the 1950s. These<sup>attempt</sup> to measure use of all types of wood products such as woodfiel, poles, sawnwood, panel products<sup>and paper.</sup> This has resulted in estimates of wood consumption for several countries, e.g. Sudan (1958), East<sup>Africa (1960),</sup> Tanzania (1970), Thailand (1970) and Zambia (1986). All of these specialized studies are useful and usually necessary supplements to methods described above as well as the household energy surveying detailed below.