BRATTLEBORO, VT. — An examination of the “transportation energy intensity” of buildings has found that getting people to and from buildings uses more energy than the buildings themselves consume. The article in the September 2007 issue of Environmental Building News shows that for an average office building in the U.S., office workers expend 30% more energy commuting to and from the building than is consumed by the building itself for heating, cooling, lighting, and other energy uses. For an office building built to modern energy codes, such as ASHRAE 90.1-2004, more than twice as much energy is used by commuters than by the building.
“This was a huge surprise,” said Alex Wilson, Environmental Building News executive editor, author of the article. “I knew that transportation energy requirements were significant, but I was amazed at the differences.”
For the article, Wilson collected average U.S. data for commute distance, vehicle fuel economy, the split among different commuting options, and the number of square feet of building per office worker to normalize transportation energy intensity in Btu/sq.ft./ year. He was then able to compare that transportation energy intensity to the average building energy use (also in Btu/sq.ft./year) for average existing office buildings and energy code-compliant buildings.
“The green building community has expended tremendous effort to reduce the operating energy use of buildings,” noted 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 dealing with climate change,” said Wilson, “we simply can’t ignore the energy consumption getting to and from our buildings.”
Many of the strategies for reducing the transportation energy intensity of buildings relate to location. The article, “Driving to Green Buildings: The Transportation Energy Intensity of Buildings,” reviews a wide range of strategies for reducing vehicle use. Such strategies 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,” said Wilson, “the building industry has only recently begun paying attention to these issues.”
In an editorial in the same issue of EBN, Wilson calls for changes to the LEED Rating System to make the credits relating to location and transportation performance-based, rather than prescriptive.
“While the prescriptive approach in LEED to site and transportation issues has served an important role,” Wilson said, “it’s time to provide a more rigorous basis for these credits.”
The full article on transportation energy intensity and the accompanying editorial can be accessed at www.BuildingGreen.com. The articles are part of BuildingGreen Suite, an online resource on green building. While this is a paid-access site, with members paying $199 per year, the articles are provided free as a sampling of content.
Additional information is available at www.BuildingGreen.com.