LEED continues to receive considerable attention in the media since it is the country's leading green building certification program. However, questions about the program's true effectiveness are beginning to surface. A recent New York Times article (August 31, 2009, "Some Buildings Not Living Up to Green Label") reported that a LEED-certified Federal Building in downtown Youngstown, Ohio was "hardly a model of energy efficiency." In fact, according to an environmental assessment conducted last year, the building reportedly did not even score high enough to qualify for the Energy Star label. This is not really "news" as the U.S. Green Building Council (USGBC) that administers the LEED program in a study last year of 121 new buildings certified through 2006 itself found that more than half (53%) did not qualify for the Energy Star label and 15% scored below 30, meaning that they used more energy per square foot than at least 70% of comparable buildings. One of the problems appears to be where the LEED points come from. The General Services Administration, which owns the Youngstown building, indicated in the Times article that points were "racked up for things like native landscaping rather than structural energy-saving features." The inferrence clearly is that perhaps the LEED criteria need re-visiting.
Interestingly, the USGBC also found from its own research that a quarter of the new buildings that have been certified do not save as much energy as their designs predicted, probably because the energy models used to predict how much energy a planned building will consume are inexact. Clearly, much still needs to be done to develop a comprehensive database of modelled versus actual building energy use information. Such a database would unquestionably improve building energy performance models.
LEED assigns credits before a building has been operated, but the only real way to know how a building is performing is to collect energy use data over time. Fortunately, as of this year the LEED program will require all newly constructed buildings to provide energy and water bills for the first five years of operation as a condition for certification.
The Canadian National Research Council also recently published an interesting study by Guy Newsham, Sandra Mancini and Benjamin Birt in August (Report NRCC-51142) that added more fuel to the fire. Their analysis of 100 LEED-certified buildings found that while LEED buildings used 18-39% less energy per square foot than their conventional counterparts in the CBECS database, 28-35% of LEED buildings used more energy. In addition, the measured energy performance of LEED buildings had little correlation with the certification level of the building or the number of energy credits achieved by the building at the time of design. This clearly presents a problem for building owners and operators who are not realizing the energy performance they were expecting.
These problems and issues have the potential to raise questions about the credibility of green building rating systems. This would be unfortunate as it could jeopardize the overall societal benefits that still accompany these rating systems. The fundamental problem in my view is that we are not giving sufficient recognition to the fact that there is a large variability between buildings (even between the same types of buildings in the same geographic location) and to do true comparisons at a statistically meaningful confidence level requires a much larger dataset than currently exists. As such, many of the comparisons (particularly against the relatively small CBECS dataset) leave much to be desired, and may in fact do more harm than good as they can be misleading. Unfortunately, the media, as expected, will often pick up the newsworthy conclusions of a just-published study, but fail to note any of the limiting conditions upon which the conclusions were drawn. As such, a top priority of our industry should be to build a much larger and more complete (and transparent) building energy performance dataset against which statistically significant energy consumption benchmarking can be done.