The average American home size shrunk in 2009 as buyers look for energy efficiency. (Photo: visulogik/flickr)

The average size of a new American house shrank 100 square feet last year to roughly 2,400 square feet

Homebuyers preferences are undergoing a green shift, including growing demand for smaller homes and energy-efficient features and appliances, according to new research from the National Association of Home Builders and Better Homes and Gardens.

Driven largely by the huge bubble in the housing market, the slumping economy has ended the long upward trend in the size of new homes in the United States, at least for now.

"The average new home size actually declined in 2009," said NAHB economics researcher, Rose Quint, at the National Association of Home Builders’ International Builders’ Show in Las Vegas last week. "There has been almost 30 years of growth in the size of homes."

Houses started in 2009 but not yet finished by the end of the year were even smaller, according to the research. The median size of these homes fell further, to 2,094 square feet.

"This year is going to be a big change in the production [building] environment," said consultant Steve Bertasso, who helps builders develop green building and energy efficiency measures.

Up to a quarter of all new homes built last year received an Energy Star rating, which means they met the guidelines for energy efficiency set by the U.S. Environmental Protection Agency, up from 11 percent in 2007.

Said consultant Bertasso, "Consumers are asking questions they didn’t ask two and a half years ago and contractors are making better decisions."

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Image adapted from visulogik at flickr under Creative Commons 2.0