Through our work on building efficiency, we here at Pike Research are often asked the question, “Which green building certification program is the most stringent?”
Short answer: It’s a really hard question to answer, and few academics and building scientists—the main groups that would be in a position to answer the question with authority—have investigated it in depth. Essentially, such a comparison would require a complex analysis of the criteria (particularly for energy efficiency) for different buildings in different climates. And with programs and the legislative landscape changing on a regular basis, the green building industry is a moving target, so it’s hard to know which is the most “stringent” at any given time.
There are dozens of green building certification programs available around the world, and builders interested in certifying a building likely have numerous options whether they’re in New York, Johannesburg, or Singapore. These programs vary in the value given to certain measures given differences in climate, construction industry norms, and other factors. Local green building professionals are likely to know the differences between programs, but the comparison may not be apples-to-apples.
What we can say for certain is that, in general, green building certification programs are becoming more stringent. The USGBC has released new versions of the LEED system on a four to five year cycle, with LEED Version 3, released in August 2009, being the most recent update. Each version is generally more rigorous than the previous one.
And that’s to be expected. If certification programs are not stringent enough, they lose their credibility and differentiating power in the market. On the other hand, if certification programs are too hard to achieve, many in the building industry are discouraged from adopting them, and uptake is limited.
An example: Although the number of available LEED points for energy efficiency is roughly the same in Versions 3 and 2.2, Version 3 is based off of the ASHRAE 90.1-2007 baseline (the energy baseline used for LEED), which is about 3-7% more stringent than 90.1-2004*. The DOE, which tracks progress on the ASHRAE 90.1 standard, is targeting an additional 30% improvement between 90.1-2004 and 90.1-2010.
Administrators of green building certification programs are trying to hit the “sweet spot” between stringency and accessibility and, as more and more building industry professionals gain familiarity with green building concepts and legislation on energy efficiency gets tougher, that sweet spot trends toward higher performing buildings. So, while it’s hard to say which program is the most stringent (and, even if we could, it could all change very quickly), the trend is definitely toward more rigorous programs.
*The results of the DOE’s determination of the difference in stringency for the two are not complete yet.