In the five years since its launch, Leadership in Energy and Environmental Design has become widely accepted as the standard of ‘greenness’ for buildings. This acceptance has come despite complaints from users that the rating system, known as LEED, it is not always an accurate indication of sustainability. Its popularity continues to grow even though little is known about how buildings certified under the still young system perform over the long run.

One of the few efforts to quantify the performance of LEED buildings is under way at the Center for the Built Environment at the University of California, Berkeley. It hopes to use its indoor environmental quality survey to compare the performance of LEED and non-rated buildings. As of November 2004, the center had collected a database of responses from 25,000 occupants of 150 buildings to questions on such topics as thermal comfort, indoor air quality and lighting. Only six of these buildings were LEED rated.

Satisfaction levels for those six buildings were "all over the map," says Charlie Huizenga, CBE research specialist. However, the second highest scorer for "overall building satisfaction" was the LEED-rated headquarters for the Chesapeake Bay Foundation, Annapolis, Md., completed in 2000. With so few rated buildings in the database "the statistics are not necessarily rigorous," admits Huizenga. CBE is actively pursuing more rated projects. Click here to view chart

In the absence of hard data, some critics contend LEED lacks scientific rigor. But the system’s creator, the nonprofit U.S. Green Building Council, counters that ease of use and widespread adoption are central to its mission. "We are trying to achieve market transformation, which requires balancing technological rigor with practical reality," says Peter Templeton, USGBC director of LEED and international programs.

Proponents of the rating system say there is evidence that this transformation is well under way. They point to such developments as competitive prices and more selection for materials once considered alternative. They also cite the growing list of municipalities, state governments and federal agencies that have adopted LEED requirements.

Users say the system also has other benefits. "Before LEED [green building] was more hit or miss," says Dennis Wilde, senior project manager for Gerding/Edlen Development Co. LLC. The developer is seeking a LEED rating for a 245-unit residential project to be complete in spring 2006 in its home city of Portland, Ore. Without such a metric, "it would be easy to ‘greenwash,’" he says.

Some sources say the resulting product is superior. "It is a systematic approach to better buildings–not just ‘green’ buildings," says Pamela Lippe, principal of E4 Inc., a New York City-based high-performance building consultant. LEED addresses problems like sick building syndrome and mold, she says.

To be successful, LEED projects require buy-in from the whole team, users say. "It gets away from ‘it’s not my job’ attitude because everyone is involved," says Thomas Perry, director of engineering services for Shawmut Design and Construction, Boston.

The certification process typically begins in an early phase of design with project "registration." The owner completes a checklist that outlines goals in six...