The U.S. Green Building Council's (USGBC) original Leadership In Energy and Environmental Design (LEED) Green Building Rating System, in place for eight years now, has spawned several offshoot green building certification programs, including LEED for Homes and the LEED for Neighborhood Development program (currently in pilot phase).

LEED's creators now see the need to align and unify the credits across the various rating programs to make the system more user-friendly, adaptive, and flexible. They also wish to implement several other initiatives that will drive its next evolution. Although the rating system will still reflect differences in building types, as LEED programs have evolved to address the complete life cycle of buildings, there has been some duplication and drift among similar credits in the different systems.

According to USGBC, further development and refining of LEED's technical framework will integrate the core elements of all the rating systems, reducing duplication and "credit drift" between systems, and giving users greater accessibility to certification information. Architect Scot Horst, LEED Steering Committee chair, says such efforts will create one unified LEED "bookshelf" that also accommodates specific building types.

"The rating systems that we have are not going away, but when someone first comes into the LEED system, they'll see a single LEED program. There will just be one," Horst explains. "In LEED online, [builders] will put in information on their project and they'll be given one of the ratings systems [to work within]. This allows us to create new rating systems for different building types much more easily. Because we can pull credits from the bookshelf, but it also allows us to recognize what's missing."

USGBC's ultimate goal is to respond to the needs of the green building marketplace without compromising LEED's rigorous standards. The group expects to introduce a more streamlined and adaptable LEED rating system by the end of 2008.