21 those who had stopped fuel stacking, perhaps reflecting the ease of cooking with LPG for small families. Figure 13 compares household size for the top two expenditure quintiles in the countries covered in Table 1. The top quintile in Cameroon, Ghana, and urban Kenya had the largest disparity in household size between those abandoning and those stacking polluting fuels. Table 1 shows that households abandoning other fuels in the top quintile in these three countries spent considerably less on LPG in absolute terms than fuel-stacking households, but up to 20 percent more in terms of LPG expenditure shares. Given the LPG expenditure share was only 1 percent in Ghana in the top quintile even for those who had abandoned polluting fuels and yet four-fifths of all households in the same quintile had retained the use of polluting fuels, affordability may not be the main reason for fuel stacking.

**Figure 13  Comparison of sizes of households abandoning versus stacking polluting fuels**

<!-- Start of picture text --> Q4 abandoning<br><!-- End of picture text --> _Source_ : World Bank staff calculations using household survey data. _Note_ : The solid portions are incremental household sizes for those staking fuels. For example, in the top quintile in Cameroon, the average size of households abandoning polluting fuels was 2.1, and that of the households stacking fuels was 3.9. * = urban households only; Q4 = quintile 4; Q5 = quintile 5; abandoning = LPG-using households that had abandoned polluting fuels; stacking = households citing LPG as their primary cooking fuel and were using polluting fuels in parallel.

When household sizes are compared across expenditure quintiles, unsurprisingly it becomes clear that there is no simple pattern with respect to household size. In every one of the 10 countries, the average size of the households with fuel stacking in the top quintile was smaller than that of LPG-consuming households abandoning all other fuels in the fourth quintile. This can be seen by comparing the full height of the green bar in Figure 13 with the patterned (non-solid) portion of the blue bar in every country. That is, the latter group of households was cooking exclusively with LPG and electricity despite being poorer in every case and larger on average than those in the top quintile who kept on using other fuels. Possible explanations include differences in market conditions and personal preferences. With respect to market conditions, some households may live closer to LPG retail outlets than others or near LPG retailers who respond immediately to requests for refills, making it easier to abandon other fuels. For differences in personal preferences, some families may like dishes that are difficult or costly to cook with LPG more than others. An example is tuo zaafi—a popular dish in northern Ghana, the goat stew of which is cooked over many hours and making of the sauce requires vigorous stirring—and such families may own stable and large wood-burning stoves to make these traditional dishes in large quantities.

What combinations of energy sources are most common among households? To answer this question, all possible combinations of energy choices were examined in several countries. The distinct combinations numbered as many as 158 in Sudan, although the top 17 combinations covered 90 percent of all households. Table 2 shows results for seven of the countries studied for abandonment of polluting fuels, listing top-ranking combinations observed in order of decreasing frequency. The combinations are