Through prediction or performance, how do we meet our energy challenges?
There is a LEED for New Construction (NC), LEED for Homes, and LEED for Existing Buildings (EB), among other certifications. The rub for Gifford is that LEED is a very popular and widespread program—some municipalities require LEED certification for new city buildings—that makes claims about energy efficiency that it can’t back up. The claims of energy saving attract builders and developers to seek LEED certification, and people in architecture firms, building energy consultants, and others in the building industry have rushed to become LEED approved providers; that means they are able to help builders meet the building requirements and fill out the paperwork needed to apply for certification. Buildings with LEED certification draw higher rents and people with “LEED AP” after their names make money shepherding builders through the certification process.
The issue hinges on a study commissioned by the USGBC in 2008. The New Buildings Institute (NBI) study compared buildings that are LEED certified with similar buildings that are not certified. NBI claims that LEED buildings use about 25-30% less energy than conventional buildings. But according to Gifford, who examined the data from the study, LEED buildings actually use about 29% more energy than conventional buildings. Gifford has legitimate concerns about how NBI gathered, sorted, and analyzed the study data. For example, the data on LEED buildings was submitted by a small percentage of LEED building owners; those who take the trouble to keep records and who want to share information on how their building performs. In another example, the mean energy use of one set of buildings is compared to the median energy use of another set, possibly skewing the results in favor of the LEED buildings.
The USGBC counters that they do not guarantee energy savings. They model energy use using a software program and only certify that a buildings meets its design specification—sustainable wood, recycled steel, interior building material that doesn’t off-gas noxious chemicals, and so on—with predicted energy efficiency only a part of the requirements for certification.
Gifford has been a thorn in the side of the USGBC for years. His criticism, along with that of others, has pushed the USGBC in the right direction. The LEED EB program requires that buildings actually perform; that they save as much energy as is predicted through the modeling software. USGBC is encouraging LEED NC building owners to take part in the LEED EH program; they are also asking LEED NC building owners to submit energy-use data that can be used to a study the effectiveness of the program. But this is not required for LEED NC certification.
Gifford is afraid that in the future someone will do a thorough study of green building performance and use the information to discredit the whole green building movement. “I predict that someday, energy will be so important that we will start to measure it,” writes Gifford in a recent Press Release. “And I predict that when that happens, building energy efficiency will start to be measured by building energy use. At that time, the currently popular systems based on computer predictions of energy use will be shown to be useless, and abandoned.”
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