LEED bashing seems to be very fashionable today.It is inevitable, and predictable, that once a company or organization achieves a certain size and influence it attracts more criticism.Indeed, LEED is getting its fair share.
Much of the recent criticism of LEED is rooted in a class action lawsuit brought against the U.S. Green Building Council by Mr. Henry Gifford, a New York mechanical contractor we first wrote about here in 2008. Mr. Gifford raised questions about the energy efficiency claims of LEED certified buildings and USGBC’s methods for making those claims.Perhaps because of his high profile lawsuit, now more often than ever before, I see articles with over-generalized, inflammatory titles like “The LEED Conspiracy” or “LEED exposed!” or “LEED is a Scam!” that go on to say that LEED buildings don’t deliver and/or that non-LEED buildings are just as efficient (or more efficient) than their LEED certified counterparts.
Everyone needs to calm down… To me this rhetoric boils down to a lack of appreciation for what LEED is and what the systems are intended to do. Let’s be specific, even if we’re being vague… The fact of the matter is that every building is different and that building green is a complex process involving many trade-offs and potential conflicts… One LEED certified, silver, gold, or platinum building is not the same as another, nor is one non-LEED building the same as another non-LEED building.
Indeed, I would submit that the entire Gifford lawsuit stems from the following single sentence in a 2008 NBI study that USGBC touted as proof of LEED’s value:
“For all 121 LEED buildings, the median measured Energy Use Intensity (EUI) was 69 kBtu/sf, 24% below (better than) the CBECS national average for all commercial building stock. Comparisons by building activity type showed similar relationships. For offices, the single most common type, LEED EUIs averaged 33% below CBECS.”
This sentence, because it compares median to mean numbers (an apples to oranges comparison), so pissed Mr. Gifford off that he couldn’t keep himself from suing just to call out the lack of care when making such sweeping claims.
While it’s ridiculous to claim “LEED is not sustainable” or “LEED is crap” as I’ve seen some people write, it’s equally silly to say, as USGBC has learned in the past, that “LEED buildings are more efficient than non LEED buildings”, without being incredibly specific.
Every building and its systems and parts needs to be evaluated individually and considered on its own. Some LEED buildings will perform and others may not… Building efficiency is an iterative constantly changing concept and inevitably conflicts and tradeoffs bubble to the surface that may not have been properly addressed or that lead to poor performance.
The following are three tradeoffs that may lead to unintended consequences in LEED projects:
Daylighting: Daylighting and increased glazing (i.e. windows vs. walls) is proven to save energy by reducing the amount of artificial light that must be produced by electricity. It also can increase employee productivity. It’s a fact, however, that windows do not insulate as well as walls, which can reduce efficiency, unless additional steps are taken (such as adding low-e window films to windows) to offset a high window to wall ratio. As such, buildings with lots of windows may use more energy than buildings with fewer windows.
Occupancy rates: Buildings that are newer and/or well-designed may have higher occupancy rates and/or longer operating hours than outdated buildings that are not well designed. LEED buildings are all required to be designed with Indoor Environmental Quality aspects applied to them, which are aimed at increasing occupant well-being and improving productivity. Some LEED IEQ credits require increased mechanical conditioning of outdoor air… the more occupants in a building, the greater amount of Co2 in a building, demanding more fresh air. Obviously, all else being equal, a building that has a higher occupancy rate than another will use more energy and electricity as those things will increase along with the number of occupants in that building and the number of hours that those employees are working.
Natural vs. Mechanical Ventilation and Indoor Comfort: Natural ventilation provides a high level of indoor comfort and is very energy efficient because power sources are not required to operate natural ventilation systems. However, with the new glass facade designs preferred by many architects, operable windows are not made available. This requires powerful mechanical HVAC systems to maintain indoor comfort to ASHRAE levels required by LEED. While the light levels indoors may be greater thanks to increased glazing, greater reliance on mechanical systems can lead to increased energy usage, even if occupants are more comfortable (and productive) as a result. Conversely, older buildings may not provide the same level of indoor environmental quality and natural light, but offer some operable windows.
What are the impacts of these small differences on occupant comfort, productivity and performance? The answer is it depends on the particular building, its occupants and their behavior in the building.
IMHO, LEED is an excellent system not only for understanding sustainability, but also for evaluating and applying the concepts of sustainability to buildings. More importantly, it is a system that will continue to evolve and improve over time… that’s the beauty of LEED!
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