Step into a new building in certain parts of U.S. and chances are pretty good that it has been built with the environment in mind (and that there is a plaque bragging about it). Maybe there’s natural lighting, a smart HVAC system, or incredible insulation. It doesn’t really matter. No matter what LEED-certified credentials the building can offer, retrofitting the teardown that came before would probably have made more environmental sense.
Preservation Green Lab, a Seattle-based think tank, released a study this week showing that, in the think tank’s words, "the greenest building is the one that’s already built, in almost every case." It’s something that intuitively makes sense, but up until now, the evidence hasn’t been quantified quite to this extent.
The study uses life cycle analysis (a method of measuring impact from cradle to grave) to compare the environmental impacts of reuse and building renovation versus construction over 75 years of use. Preservation Green Lab measured six building types-- single-family home, multifamily building, commercial office, urban village mixed-use building, elementary school, and warehouse conversion--across four U.S. cities with varying climates (representative of Portland, Phoenix, Chicago, and Atlanta).
The results are surprising, if not entirely shocking. It can take 80 years for a new "green" building to make up for the climate impact of its construction process with energy efficient features. If Portland reused and retrofitted all the commercial office buildings and single-family homes it plans to tear down over the next decade, the city could save 231,000 metric tons of CO2. That’s 15% of the country’s CO2 reduction targets for the next 10 years.
The report also presents an alarming statistic from The Brookings Institute: one-quarter of today’s buildings in the U.S. are being demolished between 2005 and 2030, creating massive amount of CO2 emissions. But at least some people are getting the hint. According to the U.S. Green Building Council, most buildings across the world that use LEED certification are now retrofits. Up until December 2011, new buildings claimed more LEED certifications.
There are numerous high-profile examples of LEED retrofits, including the Empire State Building (it expects to cut energy use by 38%) and San Francisco’s Transamerica Pyramid, which saves $700,000 each year in energy costs thanks to an onsite co-generation plant. And yet, there’s still something exciting about a new tricked-out LEED building. It’s a novelty that will hopefully fade with time.