Here’s more information from the federal Energy Information Administration: The number of households in the U.S. will increase slightly between 2010 and 2030, but the persons per household will fall just a bit — from 2.67 persons to 2.65 persons. The residential space per person will increase from 634 square feet to 727 square feet. The total energy use per household will fall from 188 million Btu in 2010 to 170 million Btu in 2030. On the average, each household will consume the energy equivalent of a bit more that 1,000 gallons of oil.