While average energy consumption dipped slightly over the winter, due to mild weather, the overall trend reflected in the survey is continuing, according to recent estimates by the Department of Energy, based on its short-term energy outlook.
Why? Improvements in efficiency for space heating, air-conditioning, and major appliances have all led to decreased consumption per household. Newer homes also tend to feature better insulation and other characteristics, such as double-pane windows, that improve the building envelope.
There are huge differences in energy spending among the states. The agency broke out data for 16 states and found that the average energy expenditure for a New Jersey household was $3,065, more than twice as much as the $1,423 for the average California household.
The difference in these expenditures is mainly due to the higher demand for heating in New Jersey, the agency said. The state's households consume 127.4 million British thermal units annually.
But Pennsylvania households spend just $2,353 on energy each year, or 96.4 million Btus annually.
The Northeast has the highest average expenditure for energy, at $2,595, which is up 11.9 percent from $2,319 in 2005. The West has the lowest, $1,570, which is up 5.3 percent from $1,491 in 2005.
How we use energy in our homes has changed substantially over the last three decades. In 2005, energy use per household was 95 million Btus of energy compared with 138 million Btus per household in 1978, a drop of 31 percent.
In 2009, 58 percent of housing units had energy-efficient, multipane windows, up from 36 percent in the 1993 survey.
Multipane windows are much more prevalent in newer homes. About 80 percent of houses built post-2000 have double- or triple-pane, energy-efficient windows, up from only 52 percent of homes constructed before 1990.
The survey shows that more than 40 million householders used caulking or weather-stripping to seal cracks and air leakages around their house, 26 million added insulation, and 68 million have at least some energy-efficient compact fluorescent (CFL) or light-emitting diode (LED) lights.
In the breakout of the 16 states, the energy agency found that 70 percent of households in California use energy-efficient lightbulbs, compared with 47 percent of households in Pennsylvania.
The survey showed that more than 44 million households now have an Energy Star-qualified refrigerator and that 41 million households have purchased an Energy Star clothes washer.
Energy Star and other federal programs have been enacted with the goal to further improve the efficiency of household equipment and appliances, from furnaces to refrigerators.
Natural gas remains the most prevalent fuel for heating homes in the United States. More than 55 million homes used natural gas as the main fuel source for space heating.
Electricity as the main heating fuel increased from 29 percent of homes in 2005 to 34 percent in 2009, while the use of fuel oil as the main heating source continued to decline.
In 1993, more than 10 percent of homes were heated with fuel oil, but by 2009, this had declined to about 6 percent.
Nearly every U.S. home has a television, and the number and size of televisions and the devices attached to them have been increasing rapidly, the survey showed.
In 2009, more than 45 million households (40 percent) had a digital video recorder attached to the most-used television. DVRs had not been widely adopted at the time of the last survey in 2005 and were not included in that survey.
The increased popularity of DVRs is significant because they are replacing or supplementing VCRs and DVD players, which consume less energy per unit than DVRs.
Personal-computing products also showed an increase in use from the 2005 survey. More than three-fourths of households now have a computer, and 39 million homes have at least two computers.
Now, to the question everyone asks, even though the answer is known in advance: Is it hot enough for you?
Air conditioners are now standard equipment in most U.S. homes.
As recently as 1993, only 68 percent of all occupied housing units had air-conditioning, but the latest survey shows 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.
Housing types and the age of the stock can determine what kind of air-conditioning predominates in an area. For example, 69 percent of air-conditioned homes in New Jersey use central equipment, compared with 28 percent in neighboring New York.
Nearly 90 percent of new homes are built with central air-conditioning. When central air-conditioning is included at the time of construction, installation is easier, and consumers can amortize costs over the life of a mortgage.
In contrast, air-conditioning retrofits or upgrades are often financed separately from a mortgage, over a much shorter time period at higher interest, and may require capital improvements such as the addition of ventilation systems and ductwork.
Contact Alan J. Heavens at 215-854-2472 or email@example.com, or follow on Twitter @alheavens.