The AIA 2030 Commitment: The Right BaselinePosted: October 31, 2011
Dee, Bergmeyer’s LEED guru, was at the end of her very long rope. We signed the AIA 2030 Commitment and were beginning to collect Energy Use Intensity (EUI) data for our projects. Her first effort was to compare the energy use metrics of all our LEED Registered projects. But she saw no clear relationship between LEED Energy & Atmosphere points and target EUI. How could this be?
“See what you got us into?” she taunted me.
Remember that TV show “Who Wants to Be A Millionaire”? If you got stuck on a question you could do something they called “phone a friend”. One of the great things about the Boston Society of Architects is our huge network of professional friends. Some of them are engineers, too. We called Chris Schaffner (new LEED Fellow!) The Green Engineer, for help. Chris stopped by the office.
We talked baseline. The AIA 2030 Commitment asks us to compare our projects’ intended energy use to 2003 CBECS data. CBECS, the Commercial Building Energy Consumption Survey, prepared by the US Energy Information Agency, is a national sample survey that collects actual energy consumption data on privately owned commercial buildings. The energy use is expressed in kBtu/sf/yr and the AIA 2030 Commitment reporting tool has a pull-down menu with EUI’s by building type built right into it. Easy.
But comparing LEED Energy & Atmosphere points to CBECS Energy Use Intensity data is like comparing apples to pomegranates. LEED E&A points are a relative measure based on energy cost. EUI is an absolute measure based on intended energy use. Sure, there might be a rough correlation between the two, but there will always be “statistical outliers” (I love it when Chris talks like that). LEED E&A points vary depending on the cost of energy. EUI varies by fuel source: natural gas is a far more efficient fuel than electricity. That might be why our all-electric LEED Platinum building bombed when compared to CBECS metrics.
The answer? Use Energy Star “Target Finder”. Target Finder – which can also be used as a reference standard for AIA 2030 Commitment – takes the CBECS data and modifies it based on things like geographic location, hours of operation, and plug & appliance loads. Chris advised us to stick with Target Finder as a baseline and not beat ourselves up trying to reconcile things that were irreconcilable.
Lesson: there really is a whole lot of variance in different approaches to establishing building energy use metrics. All those calculations are produced by people, and people have different opinions about what should be calculated and how.
In the end, I think Chris enjoyed the conversation. “It’s good that you guys are doing this!” he said. ”It’s a lot more fun than work!”
Shh. Don’t tell anyone . . .