Energy Consumption for Getting to and from Buildings Exceeds Energy Use for Operations

BRATTLEBORO, VERMONT,
Oct. 4
E-Wire

Getting people to and from buildings often uses more energy than the buildings themselves consume, according to a recent examination of the "transportation energy intensity" of buildings. The lead article in the September 2007 issue of Environmental Building News shows that for an average office building in the United States, office workers expend 30 percent more energy commuting to and from the building than the building itself consumes for heating, cooling, lighting, and other uses. For an office building built to modern energy codes, the fraction of energy used for transportation is much greater.

"This was a huge surprise," says Environmental Building News (EBN) executive editor Alex Wilson, author of the article. "I knew that transportation energy requirements were significant, but I was amazed at the differences." For the article, Wilson analyzed U.S. data on commuting distance and vehicle fuel economy, the split among commuting options, and the building square footage per employee to normalize transportation energy intensity in Btus per square foot per year. He then compared that transportation energy intensity to the average building energy use (also in Btus/ft2-yr) for average existing office buildings and buildings designed to comply with today's energy codes.

The bottom line is that for an average office building in the U.S., commuting to and from the building uses about 120,000 Btus/ft2-yr, or 30 percent more than the building itself consumes (93,000 Btu/ft2-yr). For an office building that is compliant with today's stringent energy code (ASHRAE 90.1-2004), the difference is even greater, with the transportation energy use 2.4 times the operating energy use of 51,000 Btu/ft2-yr. "The green building community has expended tremendous effort to reduce the operating energy use of buildings," notes Wilson, "but very little effort to reduce the transportation energy use of those buildings." He would like to see this change. "To achieve widely shared goals for mitigating climate change," says Wilson, "we simply can't ignore the energy consumption of getting to and from our buildings."

Many of the strategies for reducing the transportation energy intensity of buildings relate to location. The September EBN article, "Driving to Green Buildings: The Transportation Energy Intensity of Buildings," reviews a wide range of strategies for reducing vehicle use. Such strategies are often lumped under the heading "transit-oriented development" and include increasing development density, creating mixed-use development, providing various forms of public transit, restricting parking, and creating more pedestrian-friendly streetscapes.

"Although progressive urban planners have been advocating for such development features for years," says Wilson, "the building industry has only recently begun paying attention to these issues."

About Environmental Building News and BuildingGreen :

Environment Building News (EBN) is the oldest and one of the most respected sources of green building information in North America. Celebrating its 15th year of publication in 2007, EBN has never carried advertising and is supported entirely by subscription revenue. BuildingGreen, Inc., the publisher of EBN, is a 20-person company based in Brattleboro, Vermont. The article on transportation energy intensity can be accessed free at www.BuildingGreen.com.

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