Through my work on building efficiency at Pike Research, I am often asked the question, “Which green building certification program is the most stringent?”

In short: 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 kind of "moving target," so it’s hard to know which is the most “stringent” at any given time.

To date, most LEED certifications in the U.S. have covered new buildings. By the end of 2009, about 46% of cumulative LEED certifications were under the LEED for New Construction (NC) program, with an additional 15% under the Core and Shell (CS) program. CS program certifies the “guts” of a new building project if the builder doesn’t have control complete control over the interior spaces.

In contrast, only about 31% of LEED certified space is under the Existing Buildings Operations & Maintenance (EB) program. (An additional 6% is under the LEED for Commercial Interiors (CI) program, which certifies spaces within new and existing buildings, as well as another 2% under specific LEED applications for schools, retail, and certain other types of buildings).

North America and Europe are typically viewed as the leaders in the green building marketplace. Collectively, they have thousands of commercial and residential properties certified under an alphabet soup of programs such as LEED, BREEAM, and HQE. However, the Chinese market is catching up quickly—with the force of the Chinese government behind it.

There are two major green building certification offerings in China. About 150 properties in China have registered under the ubiquitous LEED program, the main label for buildings in China to date. However, the China Green Building Design and Evaluation Labels, officially launched by the Chinese government agency MOHURD (Ministry of Housing and Urban-Rural Development) in 2007, cover a similar selection of green building characteristics such as energy, land use, water, materials, and indoor air quality, and are likely to surpass LEED in China. In total, green building certifications in China could total 3 billion square feet by 2015.

If you’re a commercial building tenant looking for new office space, you’re probably comparing a few potential spaces on the basis of rent, location, the condition of the space, and maybe even the carpet color. One consideration you’re probably not looking at is the energy bills the space typically commands, either because you don’t care or because they’re simply not available.

Enter commercial benchmarking laws. These laws, which are starting to appear at the city, state, and national level worldwide, can transform the role that energy efficiency plays in driving tenant and owner decisions. The idea is that, when tenants have access to an energy profile for office space they’re considering, they may compare the energy costs of different spaces. Efficient spaces end up more desirable and less efficient spaces face higher vacancy rates. In turn, building owners looking to minimize vacancy rates, invest in energy efficiency upgrades to keep their buildings competitive in the market.

The energy efficiency retrofit industry for public buildings is relatively well developed worldwide compared to the private building retrofit industry. It is a large market in the United States, with annual revenues for energy service companies in the vicinity of U.S. $4 billion. However, long-term energy efficiency and carbon mitigation targets worldwide will rely heavily on improving the efficiency of the entire building stock. Public buildings represent only about a quarter of the total commercial building stock in the United States, and retrofits have barely begun to touch the private building stock.

One reason for the sluggishness of efficiency in the private building stock is the lack of post-retrofit data on building performance. Although there are many successful examples of retrofits in the private sector, the industry as a whole needs a robust set of data on post-retrofit performance and payback before they will be convinced that the opportunity to reduce operating costs is real, the risks are low, and the ROI is high enough to justify investments in efficiency.