The analysis states that homes built since 1990 are 27 percent larger on average than homes built in earlier decades, according to the EIA. As square footage increases, the burden on heating and cooling equipment rises, lighting requirements increase, and the likelihood that the household uses more than one refrigerator increases.

Central air conditioning is installed in 85 percent of homes built in the last two decades, resulting in a dramatic increase in the amount of residential space that is cooled — contributing to a nearly two-fold increase in electricity consumed through air conditioning. Of the 139.8 billion cooled square feet in the U.S. housing stock, over 58 billion, or 40 percent, is attributable to homes built in the last two decades. Population migration to the warmer climates of Southern and Western states accounts for much of the rise. More than 31 billion cooled square feet have been added in the South in the last two decades, which is more than the cooled square footage of homes built in that region in the previous five decades combined.

Except in the temperate climate regions along the West Coast, air conditioners are now standard equipment in most U.S. homes. As recently as 1993, only 68 percent of all occupied housing units were equipped with air conditioning units. The latest RECS results show that 87 percent of U.S. households are now equipped with air conditioning. This growth occurred among all housing types and in every census region. Wider use has coincided with much improved energy-efficiency standards for equipment, a population shift to hotter and more humid regions, and a housing boom during which average housing sizes increased.

According to results from EIA’s 2009 RECS, the stock of homes built in the 1970s and 1980s averages less than 1,800 square feet. That average increases to 2,200 square feet for homes built in the 1990s, and to 2,465 square feet for homes built in the 2000s. While the average floor area has been increasing, so has the ceiling height of many new homes. RECS data show that just 17 percent of homes built in the 1970s have higher than traditional 8-foot ceilings, while that number increases to 52 percent in homes built in the 2000s.

EIA reports reveal that the coldest areas of the U.S. have the largest homes, while the smallest homes are in milder climates. In the Midwest, where space heating accounts for half of home energy consumption, residents heat more space on average than any other part of the country. In Wisconsin, for example, the average heated square footage is nearly 2,100 square feet. By contrast, homes tend to be smaller in parts of the country where space heating is less intense. In California, where most of the population resides in mild or hot climate regions, the average heated square footage is 1,180. Differences in home size are attributed to housing market prices, income, and urbanicity, but the fact remains that homes on average are larger in areas with the most extreme winter weather.

While overall home size and air conditioned space have been increasing, the likelihood that a home will have key energy-efficient features rises as its square footage increases. Residents in larger homes consider their homes to be better insulated than those in smaller homes, and these homes tend to have more efficient windows. These trends, as well as changes in equipment, appliance, and construction standards in the last 15 years, are tempering energy consumption in larger homes.

Publication date: 05/21/2012