The case for reducing embodied greenhouse gas emissions

The Clock is Ticking

May 2011 - Most of the focus on reducing greenhouse gas (GHG) emissions (CO2 and CO2 equivalents) in the built environment has been on building operations. Rightly so: building operations—heating, cooling, lighting, and equipment—are responsible for close to 40 percent of the GHG emissions in the United States. But we also need to consider embodied GHG emissions—those from the materials and construction processes that go into making buildings. Embodied emissions are not as large as operating emissions—between 8 to 12 percent in the United States—but there are compelling reasons we should be focusing on reducing embodied GHG in our projects.

Embodied GHG emissions are often measured in terms of years of operating GHG emissions. Depending on the building's efficiency and the materials used to make the building, embodied GHG emissions typically equal 10 and 20 years' worth of operating GHG. If we assume a 100-year building life, embodied emissions don't appear very important. In Siegel & Strain's Portola Valley Town Center project, with predicted energy use about 50 percent below California's Title 24 energy code and a strong focus on using low-embodied carbon materials, we estimated the embodied GHG emissions at about 14 percent of operating emissions. read more>>>