The main floor of the addition is topped with a green roof.

An architecture firm is looking for “innovative points” to achieve a Leadership in Energy and Environmental Design (LEED) Gold certification for an expansion of the law library at the University of California at Berkeley School of Law.

A need for new space on a crowded urban campus with height restrictions drove the designers to put two of three stories of the new 52,000-square-foot addition underground. While the overall footprint of the building is reduced, the move introduced challenges to LEED certification, says Joseph Nicola, associate principal at Emeryville, Calif.-based Ratcliff Architects. It also added 5 percent to 6 percent to the $40 million expansion tab.

Most designers of LEED Gold-certified buildings can chalk up points by using natural lighting, the efficiency of steel construction and other common efficiency techniques. Such points are not available in a building that is mostly below grade, however. Even the structure’s 8,500-square-foot green roof is not large enough in proportion to the building’s area to garner any points, Nicola says.

“It’s different opportunities,” Nicola says.

The school is taking advantage of opportunities in efficiency by taking into account the natural insulating properties of the surrounding soil, looking into what Nicola calls “natural vent systems” and by putting exhaust systems below grade.

Ratcliff is also putting into place standard green building techniques such as high-efficiency glass, skylights, wood certified by the Forest Stewardship Council and low-flow toilets and faucets.