Notwithstanding the overlapping challenges of illiquid credit markets, "toxic" mortgage debt, increasing unemployment and lower fuel prices, the trend for growth in the green building movement continues to trend upward. This is evidenced not only by the growing number of green buildings, but also through the continued escalation of professionals trained in green design, and of cities that have adopted green building programs, guidelines or requirements.

Green Building is a collection of design, construction, and operation practices that significantly reduce or eliminate the negative environmental impact of development on the environment and occupants, by addressing such issues as energy efficiency, water conservation, indoor air quality, waste reduction and occupant productivity and health. The two most popular green building programs helping to drive this transformation in the building construction industry are the U.S. Green Building Council's Leadership in Energy and Environmental Design (LEED®) rating system and the U.S. Environmental Protection Agency's ENERGY STAR® Label for homes and commercial and industrial buildings. The National Association of Home Builders (NAHB), which launched its national green home building certification program in 2008, is also viewed as a driving force behind green building in the residential sector.

LEED Certification System
The U.S. Green Building Council (USGBC) is a nonprofit organization that was started in 1993. Today, the USGBC has 79 local chapters, almost 18,000 organizations and members, and thousands of volunteers. Since 2000, the USGBC's membership has more than tripled. Additionally, more than 62,000 industry participants have passed a national exam to become "LEED Accredited Professionals."

Additionally, more than 4.2 billion square feet of commercial building space is involved with the LEED green building certification system. There are a total of 31,000 LEED registered and certified projects in the U.S.

The USGBC's LEED green building certification system is a voluntary, consensus-based national standard for developing high-performance, sustainable buildings. Points are awarded for sustainable sites, water efficiency, energy and atmosphere, materials and resources, indoor environmental quality and design innovation. LEED certification provides independent, third-party verification that a building satisfied the USGBC's requirements for green building. Higher point scores can result in Silver, Gold and Platinum ratings. The LEED for New Construction rating system was first released in 2000. LEED now consists of the following menu of rating systems:

• LEED for New Construction (2000)
• LEED for Commercial Interiors (2004)
• LEED for Existing Buildings (2004)
• LEED for Core and Shell Construction (2006)
• LEED for Homes (2007)
• LEED for Neighborhood Development, Retail and Healthcare are currently in pilot test.

Despite the promising forecast ahead, it must be noted in USGBC's 2008 Annual Report that there are that challenges that lie ahead. USGBC recognizes the green building successes of the past few years must be tempered by the fact that "the biggest danger is calling green ‘mainstream' when out of the 100 million homes out there only 2% to 10% are green."

ENERGY STAR for Commercial Buildings
The U.S. EPA ENERGY STAR label for commercial buildings was first introduced in 1999. As its name implies, this program focuses on energy efficiency, which is different than LEED, which includes energy efficiency as one of several green building categories. EPA's online tool, Portfolio Manager, is used to rate commercial buildings on a scale of 1 to 100 against similar buildings nationwide.

To earn an ENERGY STAR label, a facility must achieve a score of 75 or higher, which indicates that it ranks among the top 25% of facilities in the country for energy performance. According to Energy Star's 2007 Annual Report, the number of ENERGY STAR labeled buildings reached 4,000 in 2007, representing over 740 million square feet. It represents the most buildings that have ever qualified for the ENERGY STAR label in one year.

In 2007, over 62,000 buildings and 7.5 billion square feet were rated by EPA Portfolio Manager, which is an increase of more than 50% compared to 2006. The portfolio of rated buildings includes 55% of hospital space, more than 50% of supermarket space, 30% of office building space, nearly 25% of school space, and nearly 25% of hotel space across the country.

U.S. EPA data shows that for the first 11 months of 2008, roughly 2,000 commercial buildings have received the ENERGY STAR label. This represents a quarter of the total number of buildings that have been labeled during the program's 10-year history. The data also shows that more than 2 billion square feet of U.S. commercial space was benchmarked through ENERGY STAR in the first half of the year alone. According to December 2008 tallies from the EPA, the current total is 6,086 for ENERGY STAR labeled buildings.

ENERGY STAR Qualified New Homes
The ENERGY STAR label is also available in the residential market. To attain it, a home must meet energy efficiency guidelines set by the U.S. EPA. According to the EPA, these homes are at least 15% more energy efficient than homes built to the 2004 International Residential Code (IRC), and may include additional energy-saving features that make them, on average, 20-30% more efficient than conventional homes.

According to ENERGY STAR's 2007 Annual Report, in 2007 ENERGY STAR qualified homes represented about 12% of the housing market nationwide and equaled or exceed 20 percent of the housing stock in more than 50 markets. To date, a total of almost 850,000 ENERGY STAR qualified homes have been constructed.

To further promote ENERGY STAR qualified homes, the EPA is working to promote ENERGY STAR standards as a prerequisite to other green building programs. For example, LEED requires, at a minimum, that a LEED Home be built to the ENERGY STAR requirements. The ENERGY STAR Indoor Air Package, which addresses the indoor environment quality of green building, also requires that homes are first qualified as ENERGY STAR. While the EPA's newest program, Water Sense Labeled New Homes, does not require ENERGY STAR-qualified homes as a first step toward certification, it does require new appliances, such as dishwashers and clothes washers, to carry the ENERGY STAR label. The program, currently in draft phase, will establish water-efficient guidelines for single-family homes to help reduce both indoor and outdoor water use.

NAHB National Green Home Program
The National Association of Home Builders (NAHB) National Green Building Certification Program began in January of 2008. The certification program is based on the NAHB voluntary Model Green Home Building Guidelines, published in 2005. Over 100,000 green homes have been built and certified by NAHB members participating in voluntary local green building programs that utilize the NAHB Model Green Home Building Guidelines since 2006. These programs are expected to certify another 35,000 green homes by the end of 2008.

As of late 2008, homes certified under the national program also had the option of being certified based on the National Green Building Standard (ICC 700-2008). There are three green home certification levels available in the NAHB Model Green Home Building Guidelines—Bronze, Silver, and Gold. (An additional Emerald level will be available in the National Green Building Standard.) The green levels and certifications address seven key green construction areas: Site, Resource Efficiency, Energy Efficiency, Water Efficiency, Indoor Environmental Quality, Homeowner Education, and Global Impact. Currently there are 79 NAHB green certified homes.

‘REGREEN' for Existing Homes
With the exception of LEED-EB (Existing Buildings), the programs described above are for new construction. Equally if not more important to the realization of green building objectives, are trends in green home remodeling. Moreover, expenditures on existing homes tend to be somewhat inversely related to expenditures on new construction. Therefore, green home remodeling may be thought of as a kind of trend "hedge" should new construction in the green sector start to contract with the overall downturn in the economy.

Home Performance with ENERGY STAR is a program supported by U.S. EPA and U.S. Department of Energy (DOE) to provide home performance audits by qualified auditors and energy efficiency retrofits by qualified contractors. According to the EPA, the average home can realize typical energy savings of more than 20%, and save between $400 and $500 a year if homeowners implement energy efficient recommendations.

According to ENERGY STAR's 2007 Annual Report, more than 11,000 Home Performance with ENERGY STAR retrofits were completed in 2007, bringing the total number of homes improved under this program to over 38,000 retrofits. EPA projects that more than 50,000 homes will improve through Home Performance with ENERGY STAR.

REGREEN is a comprehensive remodeling program aimed at greening existing homes in several green building categories. It is a set of green home remodeling guidelines that was developed by the American Society of Interior Designers (ASID) Foundation and the U.S. Green Building Council (USGBC) in 2008. Unlike the LEED for Homes rating system, which offers a certification program for new homes, REGREEN provides guidelines for remodels and renovations but does not certify projects. It aims to provide the information and resources necessary to increase the demand and capacity for green home remodeling.

Future Green Building Trends
By 2010, approximately 10% of commercial construction starts are expected to be green, and the value of green building construction is projected to increase from $10 billion in 2005 to $36-$49 billion, and could reach $60 billion by 2020 and climb to $96-$140 billion by 2013. Policy makers are contributing to those numbers by mandating LEED-certified development projects or ENERGY STAR benchmarking in cities such as Dallas, Portland, Los Angeles, San Francisco and Washington, DC.

There are also examples of cities and states that have instituted their own green building program, as in the case of the State of Minnesota Sustainable Building Guidelines. According to a report from the American Institute of Architects (AIA), the number of cities with green-building programs has increased 418% since 2003. In addition, several states have implemented greenhouse gas emissions targets, and carbon and solar renewable credit trading platforms. These contribute to demand for green building. Finally, the updated national building codes that are due out this year and next are expected to push the envelope farther when it comes to key aspects of green building such as energy efficiency and indoor air quality.

In the 1990s, during the early days of LEED, green building was adopted mainly by government projects, schools and nonprofit organizations. By early 2005, the private sector had discovered the "business case" for green buildings and now leads the way in new green projects for all sectors, including office buildings, retail, hospitality, recreation and healthcare. By 2009, 82% of corporations are expected to be greening at least 16% of their real estate portfolios. Of these corporations, it is predicted that 18% will be greening more than 60% of their real estate portfolios.

There is strong evidence that green building—or at least aspects of it—constitutes a long-term trend and not a passing fad. As green building continues to mature, key questions as to its performance are becoming more common. A standardized set of metrics and routine data collection needs to be established as part of the growing practice of Building Performance Evaluation (BPE). For green building to evolve, systems need to be put into place to track real-time and long-term trends, and to provide individual and collective feedback on the performance of green buildings.

Jennifer Senick is executive director, with Rutgers Center for Green Building, Rutgers University.