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.

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.

Although the rollout of the Green Building Design and Evaluation Labels was slow at first, industry sources report that hundreds of buildings are being certified currently, thanks to strong support from the Chinese government. The government set green building as one of its major priorities in its 11th Five Year Plan. While there are few (if any) prescriptive policies demanding building certification, it is likely that the Chinese labels will start to appear with greater frequency in governmental buildings in the near future.

On the ground, the China Green Building Council has helped kickstart a broad network of professionals working on green building around the country. This is no small task in a country that is adding 2 billion square meters (about 20 billion square feet) of new space every year.

While the potential scale of green building activity in China will likely eclipse that of other countries in the coming years, green building leaders are reaching out to other countries to collaborate and share best practices. For example, in April, Rick Fedrizzi, the chairman of the U.S. Green Building Council (USGBC) signed a memorandum of understanding (MOU) with Youwei Wang, the chairman of the China Green Building Council. The purpose of the MOU was to initiate collaboration on green building activities and to partner on carbon emissions reductions in the two countries. It will be interesting to see how the partnership plays out.

China will have to smooth out a few bumps in the road before green building really takes off, though. The construction supply chain in China is not well adapted to programs such as LEED, and certification costs can soar when there are few contractors and building materials vendors with products and services that comply with LEED. Inevitably, China will retool its construction industry in support of green building certification as it looks to address energy and environmental challenges as a country.

In the day-to-day competitive battles between smart meter Neighborhood Area Networking (NAN) and radio technologies, discussion of the “best” transmission frequency is often at the forefront, and for good reason. Transmission frequency influences range, propagation through objects such as foliage, and the communications data throughput. So the win by Trilliant at Maine Central Power (CMP), announced last week along with a big $106 million investment by ABB, GE, and others, is especially interesting.

Trilliant has been a bit of a lone wolf in the use of 2.4 GHz for their RF mesh NAN, based on an IEEE 802.15.4 standard-based MAC/PHY protocol layer. Virtually everyone else, including Silver Spring Networks, Itron, Landis+Gyr, and Elster, use proprietary MAC/PHYs in the 902-928 MHz frequency range. Why? Because according to the physics of the Friis Transmission Equation, all else being equal, communications will travel farther at 900 Mhz than 2.4 GHz. The “2.4G vs. 900M” arguments go well beyond the NAN; a quick Google will get you similar battles over cordless phones, headsets, and other applications. This is also a fixture of the ZigBee vs. Z-Wave war for wireless home automation.

The issue is that the “all else being equal” caveat is rarely true in practice. Radio transmit power, encoding scheme efficiency, receiver sensitivity, noise rejection characteristics, and antenna design are all major factors in real-world performance. A slightly more robust form of Friis’ equation (see figure below) contains enough variables to make one think it really is rocket science. A major benefit of 2.4 GHz is the possible increased data bandwidth. For example, the IEEE 802.15.4 MAC/PHY used by Trilliant has a link data rate of 250 kbps, while the competing 900 MHz offerings range from 19.2 kbps to ~150 kbps – a significant difference.

What makes Trilliant’s win at Central Maine Power most interesting is the nature of CMP’s service territory, which covers about a third of Maine. Those outside New England may not realize that Maine is a very big place. CMP’s service territory is bigger than nine U.S. states, including each of the remaining New England states. With a relatively low customer density (only 600,000 customers), one would assume than NAN communications range was a major decision factor.

So the lesson may be that NAN evaluation should not stop at Friis. There are many other considerations, including potential interference from other unlicensed users at that frequency, immunity to weather, operation in a multipath environment, mesh protocol robustness, and radio design characteristics, that should be included in any assessment. One thing is sure – the arguments will continue to be made on both sides, and real-world experience will trump fancy equations every 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).

However, the tides have shifted in the last 18 months toward the existing building stock. In 2009, LEED EB surpassed LEED NC in terms of certified floor area by 15% in the U.S. How can we explain this shift?

One reason is that the last few years have witnessed a trend toward consolidation of building service companies. Many of the largest building service providers in the United States—including CB Richard Ellis, Jones Lang LaSalle, and Hines Corporation—are also the leaders in providing green building services. As a result, the early efforts of these companies to establish themselves as leaders in the green building sector are being amplified through their recent acquisitions as well as their prior service base.

The recession has also driven interest in existing buildings. Just as the recession all but halted new construction, it also drove many building managers to look at ways to reduce operating expenses in their existing building stock. Financing options such as energy performance contracts have helped capital-constrained building managers finance energy efficiency projects for existing buildings even through the recession, and LEED EB certification has accompanied many of these projects.

The recession has also placed pressure on certifying buildings in the slow but competitive rentals market. LEED certification can help differentiate a building from non-certified buildings and, for the few commercial tenants looking to relocate or rent for the first time, a LEED certification is highly attractive.

There is tremendous untapped opportunity for certifying the existing building stock. The momentum that LEED EB has gained even in the recession will only grow stronger as the building industry picks up as whole.