Bren Hall on the campus of the University of California, Santa Barbara, is a modernist academic building perched on a bluff overlooking the Pacific Ocean. Housing the university's Donald Bren School of Environmental Science and Management, the sleek collection of geometric shapes includes classrooms, labs, study areas, offices and common rooms, and was completed in 2003 at a cost of about $26 million.

Former Vice President Al Gore's 10,000-square-foot mansion was constructed 80 years ago in the Nashville suburb of Belle Meade. Purchased five years ago for $2.3 million, it includes eight bathrooms and an industrial-size kitchen, and replicates the classic plantation architecture of the antebellum South, with a symmetrical facade and two-story Greek columns flanking the formal entrance.

Despite their apparent geographic and architectural dissimilarities, Bren Hall and Gore's home share one important attribute in an era of growing concern about the carbon footprint of the built environment and its implications for global climate change: Both structures have been recognized for their eco-friendliness by the nation's leading promoter of sustainable building design, the United States Green Building Council (USGBC).

Gore's home recently achieved gold status, the second-highest level, under the council's Leadership in Energy and Environmental Design (LEED) certification program. Bren Hall has platinum-level LEED certification, the highest rating, and is regarded as the most technologically advanced and resource-efficient laboratory building in the nation.

In the case of the Gore home, certification was the result of an ambitious renovation project that included installation of solar panels, a rainwater-collection system, geothermal heating and replacement lighting. Bren Hall, on the other hand, was designed for maximum efficiency from the start. The list of its special features runs to several pages, including photovoltaic panels; site and building design strategies intended to maximize availability of natural light and air flow; building materials incorporating recycled concrete, steel, wallboard and other components; water-efficient plumbing fixtures; and super-efficient motors, boilers and other mechanical devices.

Green building strategies are being embraced by a growing number of local and state governments. In some cases, the trend is being driven by a desire to reduce water and electrical use in areas where those critical resources are in limited supply or costly to import. Some elected officials also seem motivated, however, by frustration over the Bush administration's foot-dragging in response to scientific warnings about global warming, and are determined to take steps on their own to reduce greenhouse gas emissions.

Cities and counties cannot regulate tailpipe emissions or, for the most part, coal-burning power plants. They can, however, regulate land use and building design, and that's where they are focusing. More than 720 mayors nationwide have pledged to meet the emission-reduction targets of the Kyoto Protocol, an international treaty to address global warming that the Bush administration opposes. The local governments are using building design standards and zoning ordinances to cut emissions.

Los Angeles Mayor Antonio Villaraigosa, for example, has pledged to reduce the city's greenhouse-gas emissions 35% below 1990 levels by 2030. In November, the Los Angeles Planning Commission voted to require that new buildings with more than 50 housing units or 50,000 square feet of floor space meet at least the lowest level of LEED certification standards. The commission also approved rules that would expedite permitting, perhaps shaving as much as a year off the processing time, for builders who are willing to seek silver certification — the third-highest of the four LEED certification levels — for their projects.

Other cities have also adopted strict green building rules for private development, including San Francisco, Boston and Washington, D.C. Santa Monica has rules and incentives similar to those being adopted in Los Angeles, although they apply even to small projects. San Francisco intends to require new buildings of at least 25,000 square feet to meet LEED gold criteria by 2012.

There are practical advantages to building green. Although constructions costs can be inflated when builders employ recycled or low-impact materials and ultra-efficient lighting, heating, water and air-conditioning systems, the operating costs for such structures typically save owners and tenants money over time. There is also the appeal to consumer conscience as energy prices — and sea level — rise.

But it's easier to make green claims than it is to back them up. To weed out imposters, a number of third-party certification programs have popped up to verify the eco-friendliness of buildings and assure customers that they are getting their money's worth. Green-building certification programs include the U.S. Environmental Protection Agency's Energy Star homes project, the American Lung Association's Health House program, the Environments for Living program and the California Building Industry Association's Green Builder program. Some focus on energy efficiency while others concern themselves with encouraging use of least-toxic building materials or reducing use of virgin resources.

But the USGBC's LEED program is the most well-established and widely used set of standards, to the point that even developers outside urban areas are seeing LEED certification as a potential marketing tool for buyers with an ecological conscience. Ginn Development, for example, recently announced it would seek LEED certification of homes and condos it is building in association with a ski resort in Vail, Colo.

The LEED rating system was developed in 2000 by the USGBC, a nonprofit association of more than 12,400 member companies and organizations. Founded in 1993, the council includes among its membership building owners, real estate developers, architects, designers, engineers, contractors, manufacturers, nonprofits and government agencies.

The heart of the LEED certification program is an extensive checklist of materials, site strategies and design elements generally intended to reduce the environmental impact of a structure. The checklist is divided into six categories: sustainable sites, water efficiency, energy and atmosphere, materials and resources, indoor environmental quality, and innovation in design. Within each category is a set of specific green building criteria and prerequisites; buildings submitted for LEED review earn points for satisfying those requirements. Earn enough points and the building achieves one of the four levels of LEED certification.

It's neither easy nor cheap to get your building certified. Although the average fee is only about $2,000 when submitting building documentation for review (the amount varies with the size of the project), producing that required documentation is far costlier — as much as $100,000, according to some experts. That is not much to add to the price of a multimillion-dollar project, but it's a heavy burden for smaller ones.

The potential effect of greener structures is vast. According to Doug Newman, executive director of the National Energy Center for Sustainable Communities, buildings account for 65% of electricity consumption and 30% of greenhouse gas emissions in the United States. And over the next 25 years, the country will need 427 billion square feet of buildings to accommodate growth, about half of which will be new construction.

LEED-certified buildings so far are only a drop in the global-warming bucket. According to the USGBC, there are more than 10,300 homes across the country involved in the LEED certification pilot program for residential structures, and only 400 of them have been certified. That is not much when you consider that the U.S. housing stock increases by about 2 million units a year. But many analysts forecast that the green share of building starts will jump in coming years, and the eco-friendly sector will expand to account for 10% of the market by 2010.

The LEED program has recently expanded its focus beyond building design to community design, recognizing that the way you organize land use can have as great an impact on energy consumption as the type of light bulbs and windows you install in the buildings. According to Newman, 70% of a community's energy consumption is influenced by urban land-use allocation, site design and development practices.

LEED for Neighborhood Development (LEED-ND) is a rating system, according to the USGBC, "that integrates the principles of smart growth, new urbanism and green building into the first national standard for neighborhood design." The rating system has been developed cooperatively by the Congress for the New Urbanism, the Natural Resources Defense Council and the USGBC.

The LEED-ND program is still in its infancy. The call for applications to the certification pilot program was issued in 2007, and 238 projects from 39 states and six countries were selected. The proponents of those projects are still gathering the information that will be submitted to the USGBC for evaluation. The pilot program is expected to be revised this year before adoption of a final certification process in 2009.


Resources:

U.S. Green Building Council: http://www.usgbc.org/DisplayPage.aspx?CMSPageID=51
Guide to green building certification programs: http://www.pathnet.org/sp.asp?id=20978
National Energy Center for Sustainable Communities: http://www.necsc.us/
Center for Resource Solutions (certification program for low-carbon energy sources): http://www.resource-solutions.org/mv/index.htm
U.S. Environmental Protection Agency's Energy Star homes project: http://www.energystar.gov/index.cfm?c=new_homes.hm_index
American Lung Association's Health House program: http://www.healthhouse.org/
Environments for Living program: http://www.eflhome.com/index.jsp?action=fl_li
California Green Builder: http://www.cagreenbuilder.org/