Living Future 2010 and the Emergence of zEPI (Zero Energy Performance Index)

This year’s Living Future conference in Seattle provided many highlights. From the simple yet inspirational message of working together provided by Dr. John Francis to the heartfelt thanks (and slight roasting) NBI’s technical director Mark Frankel received as outgoing Director of the Cascadia Board (don’t worry, he was reelected to the Board). Amongst spirited discussions on realizing the Living Building Challenge and educational sessions on such topics as occupant behavior there were a number of comments concerning Seattle’s impending building disclosure ordinance, which was approved at the end of January. This makes Seattle the third U.S. city (after New York City and Washington DC) to require buildings to benchmark their energy use and provide the City with ratings that can be compared from building to building. The frequency of comments illustrated the importance of this topic and perhaps offered an explanation for why both sessions related to measured performance on Friday were standing room only.The morning session on outcome-based energy codes was moderated by Liz Dunn (Preservation Green Lab), whose panelists included Dave Hewitt (NBI), Jayson Antonoff (City of Seattle) and Dave Ramslie (City of Vancouver, BC).  While Dave Hewitt made the broader case for the move to outcome-based codes, Jayson and Dave Ramslie talked about how their respective cities plan to use outcome-based codes to distribute incentives and meet targeted carbon reductions. A question posed by an audience member regarding an established code baseline set the stage for the introduction of the Zero Energy Performance Index (zEPI).The basis for zEPI can be traced back to a scale presented in a paper written by Charles Eley called Rethinking Percent Savings. Eley makes the compelling case for the adoption of a more stable,  absolute scale that would be used to benchmark buildings as opposed to the percent-better-than-code baselines (ASHRAE 90.1 2004, 2007, etc.) which are continuously shifting as more stringent codes are developed and adopted. The scale establishes zero net-energy as the absolute goal. This makes the need for a baseline obsolete; the only measurement that matters is how far a building deviates from zero net-energy. The scale would go from zero to 100, with 100 representing the average energy consumption based on 2003 CBECS (Commercial Buildings Energy Consumption Survey) data.The absolute nature of Eley’s scale has made it easily applicable to code language, and it is currently written in draft form into the ICC’s new Green Code (IgCC) as zEPI. NBI has become a big proponent of zEPI because it sets a constant goal (zero) and shifts the conversation from percent better than code to percent from zero, which is the kind of market shift we believe needs to happen if net-zero is to ever be fully realized.

Update: In a recent New York Times op-ed piece, author Alec Appelbaum faults the LEED rating for functioning “more like a snapshot taken at its [the building’s] opening, not a promise of performance.”  Moving forward with an outcome-based code would enable governmental agencies to “ensure long-term compliance with the program’s ideals … .”