The U.S. Government Accountability Office says that while most federal agencies use third-party green-building rating systems, they still find requirements tough to implement on new projects and renovations.

In a July 23 report, GAO says agencies use certification programs such as Leadership in Energy and Environmental Design (LEED), the Living Building Challenge and Green Globes to comply with green-building mandates—such as reduced water consumption and improved air quality—under various laws, executive orders and policies.

“Officials from all five select agencies … told us that third-party certification helps ensure compliance with key green-building requirements by holding contractors and agency project teams accountable for incorporating the requirements,” says GAO.

But many are finding implementation challenges because of large inventories of buildings that need to be built or renovated,or due to the need to build facilities for which the requirements are difficult to implement.

According to the report, the Veterans Administration has found it difficult to balance mission requirements—new safety mandates and extended hours to address patient backlogs—with implementing some energy and water conservation requirements,

A review by Pacific Northwest National Laboratory found that, of the three systems it evaluated, none met all the federal green-building requirements.

“Several select agencies … have developed crosswalks that align specific credit categories in third-party certification systems with key federal green-building requirements,” the GAO report says.

The U.S. Dept. of Energy’s National Renewable Energy Laboratory said it used crosswalks developed by the U.S. General Services Administration and the Interior Dept., while designing its Research Support Facility in Colorado. The building obtained a LEED Platinum rating, and it complies with 2008 guidance adopted by the federal Council on Environmental Quality. (ENR 4/11/2011, p. 46)

The council is expected to release updated “guiding principles” later this summer. In a statement, Sen. Tom Carper (D-Del.), urged it “to review the points raised in this report as it continues to revise the guiding principles for federal green buildings.”