Say anything remotely negative about green building these days and you're likely to raise eyebrows in certain politically correct circles, but that does not mean we shouldn't be taking a hard-nosed look at some of the claims being made for sustainable buildings.
That's why the research being conducted by the U.S. Energy Department's Paul Torcellini and colleagues at the National Renewable Energy Lab in Golden, Colo., is so refreshing.
For the last couple of years, the NREL team has been documenting the operating performance of six green buildings to determine their actual performance relative to their design goals. The six are the Lewis Center for Environmental Studies at Oberlin (Ohio) College; the Zion (Utah) National Park visitor center; BigHorn Home Improvement Center, Silverthorne, Colo.; NREL's own Thermal Test Facility; the Cambria Office Building, Ebensburg, Pa.; and the Chesapeake Bay Foundation, Annapolis, Md.
In an article in the September ASHRAE Journal, Torcellini, NREL colleague Ron Judkoff, and the DOE's Drury Crawley report that energy performance in each of these buildings was "significantly better" than minimum code requirements, and each "broke new ground" in sustainable design.
But, the authors note, "even though each building is a good performer, each used more energy than calculated during design." Design teams were "a bit too optimistic" about how occupants of these buildings would accept advanced technology systems and how they would behave toward them.
As a result, the researchers say, energy consumption was higher and photovoltaic energy production was lower than simulations predicted. Daylighting contributed less to energy savings than predicted, "which meant more electrical lighting was used." Sensors and controls for electrical lighting often did not work properly, resulting in energy loss.
The DOE researchers found that construction details and specifications were not always installed as designed, leading to thermal leaks in the building envelope. And while they praise the design teams for setting concrete goals, they note that these goals were not always optimal or comprehensive. For example, the Chesapeake Bay Foundation met its goal of achieving LEED 1.0 Platinum, but "energy was not a prime goal, and although the building is a good energy performer, the energy use is greater than some of the other buildings." Oberlin had the most aggressive energy goal (which it met), but it did not do well in terms of energy cost.
I don't want to create the impression that the DOE team is a bunch of naysayers when it comes to green technology. Clearly, they're all for experimentation in daylighting, radiant heating, mixed-mode ventilation, photovoltaics, and ground source heat pumps. They're just not willing to accept the sometimes inflated claims being made for these green technologies.