The use of natural gas by households varied widely among the four different types of housing units (Figure 1). Two types—single-family units and two-to-four household units—used natural gas more widely for any end-use and for space heating. Mobile homes used the fuel less commonly. Less than 40 percent used natural gas; in those units, electricity and liquefied petroleum gas (LPG) were more often used for heating.

Natural gas consumption and expenditures were lowest for households that occupied structures with five-or-more units (Figures 2 and 3). Those units were much smaller than average, had common walls between the units, and required less total energy for heating. In contrast, mobile homes consumed and spent relatively more for natural gas. Although they were similar in size to five-or-more household units, they had greater external wall area through which heat could be lost.

The various residential housing types showed little variation in natural gas prices (Figure 4). The impact of higher natural gas prices projected by STEO for 2001 is shown in Figure 3. At 2001 prices, single-family households would spend 34 percent more per household than in 1997.