The New LEED: All About Weightings

The LEED 2009 rating systems are about to debut. In this space over the next few months, I’ll discuss various aspects of the new LEED. Today’s post is all about credit weightings—scientifically grounded re-evaluations that place an increased emphasis on energy use and carbon emission reductions.

Recognition that everything isn’t equally important in large part drove the reorganization of LEED 2009. In the current system, credits are weighted equally with extra points available only for better performance, a criticism levied at LEED since the beginning. For example, if a project team spends $1500 on bike racks they get one point; if they spend $20,000 on commissioning, they get one point. The bike racks are important—they get automobiles off the roads—but the environmental and human health impacts that result from commissioning are multidimensional.

Holley Henderson of H2 Ecodesign and the interior design representative to the LEED Steering Committee explains how each credit was dissected and evaluated according to its environmental good. “With these changes the point allocations are no longer subjective. Rather, they have validity that can be traced back in an analytical way to environmental and human health impacts.”

The value of credits are now determined through a basic weightings equation which brings together information on building impacts, building functions and the performance of individual credits. The tool, developed to synthesize large quantities of relevant information, is complex but also a logical, transparent framework that incorporates the best available science.

Clearly there are practical implications of the weightings changes that will affect LEED projects as we move forward. As shown on the charts, the current LEED-CI emphasizes Indoor Environmental Quality (IEQ) and Materials and Resources (MR) over the other credit categories. Conversely, LEED 2009 allocates a greater number of points to Sustainable Sites (SS), Water Efficiency (WE) and, in particular, to Energy and Atmosphere (EA).

This begs the question, are the impacts of materials and the importance of human well-being in buildings being diminished or are they rightly overshadowed by the critical importance of climate and carbon? Scot Horst, chair of the LEED Steering Committee, admits that little attention was paid to the MR credits during the weightings exercise because of ongoing work on an LCA approach that will significantly alter how materials are considered in projects. We’ll eagerly await this development, but still, this discussion needs to happen.

Visit my blog post on the LEED 2009 Timeline.