A Material Issue

USGBC's proposed credit changes focus on life cycle assessment.

It can take between 20 and 80 years for the impacts of a building's operation to catch up with the impacts of its initial construction: For the first few decades of a building's life most of its environmental footprint is from the materials used to make it. That insight is behind the effort to reinvent the materials credits in the next version of LEED, according to Scot Horst, SVP for LEED at the U.S. Green Building Council.

The proposed LEED v4 rating includes points for using environmental life-cycle assessment (LCA) to reduce the environmental burdens of a building's structure and shell. That approach should encourage techniques to optimize material quantities, says Horst.

LCA is also at the heart of a new credit called Material Disclosure and Optimization, encouraging the use of products with Environmental Product Declarations (EPDs), which are independently verified summaries of LCA studies. LEED v4 also includes separate credits dealing with human and ecological health hazards and habitat disruption.

The proposed changes are highly controversial. Major trade associations, led by the American Chemistry Council, object to the new disclosure and avoidance requirements, calling them unscientific and biased. These groups are using their political muscle to undermine government support for LEED.

Building professionals don't necessarily disagree with the direction of the new credits, but are wary of changing the system so radically all at once, and concerned that tools and resources needed to meet the new credits are not yet available. In response to these latter concerns, the USGBC has delayed the launch of the new system from 2012 to 2013, and promised that the previous system would remain available as an option until 2015.

Keywords:

• LEED v4;
• LEED 2009;
• materials;
• life cycle assessment;
• LCA;
• Environmental Product Declarations;
• EPD