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Do Green Building Ratings Need an Overhaul?
BUILDER / July 10, 2013
Yes or No?
Yes. New standards should include life-cycle assessments.
Robert Zabcik is director of R&D at NCI Building Systems, a metal components producer.
We anticipate a divergent evolution, where the rating system involves more complicated and holistic scientific models with sophisticated rubrics to determine a building’s performance.
This would be a kind of “rating system on steroids,” in which a computer does most of the calculation. Much of the simpler criteria that are currently in existing green building rating systems would appear as requirements in high-performance building standards (aka “green codes”), and some might even find their way into traditional building codes.
We are seeing hints of this evolution in commercial construction. LEED v4 is a traditional rating system, but will have credits that evaluate environmental performance using a Life Cycle Assessment (LCA) model. Meanwhile, many of the original LEED and Energy Star requirements can be found, in a tweaked form, within documents like ASHRAE 189.1 (high-performance design standard) and the International Green Construction Code, or IgCC.
A residential rating system might see ICC-700 evolve into a base code, with performance-based criteria for buildings that strive to achieve net-zero energy and carbon as an addendum.
By adopting this approach, NAHB, USGBC, and other standards-setting groups would be free to push the envelope with increased sophistication and LCA playing a critical part.
Much as an energy model simulates building energy systems, LCA tools simulate material and energy flows, which help determine the environmental impacts of the entire building life cycle. In LEED v4, this is limited to building creation, but it could naturally grow to include use-phase effects, including energy, deconstruction, and disposal/reclamation. With additional development, an LCA model has the potential to encompass the scope of LEED and ICC-700 as they exist today.