When the roof of the Robert J. Dole U.S. Courthouse in Kansas City, Kan., began leaking last summer, it couldn't have come at a better time.

Had the roof failed a year earlier, it likely would have been replaced with a standard-issue asphalt topper that would have kept employees and visitors dry but wouldn't have been anything special.

But the 15-year-old roof failed just months after Congress approved the Recovery Act, which funneled $5.5 billion to the General Services Administration to build and repair federal facilities and make them more energy efficient. GSA decided to use $1.6 million in Recovery Act funds to replace the courthouse roof with an energy-efficient alternative that will not only lower electric bills but also take part of the building off the commercial power grid entirely.

"Normally, in the average year, we would have put on the typical roof — not anything bad, but it wouldn't have been anything great," said Linda Phillips, who manages GSA's Recovery Act spending for the Heartland Region, where the courthouse is located. "What Recovery has done is allow us to put on a superior roof."

The new roof, which was completed in December, uses a mix of two clean-energy technologies that are at the cutting edge of roof design.

The first is a white membrane roof — a so-called cool roof — that deflects the sun's rays, keeping the building cooler in the summer and generating less heat for the surrounding area.

The roof also is highly insulated. The effectiveness of roof insulation in resisting heat flow is measured by a metric called an R-value, which increases numerically depending on thickness, density and material used. Current building standards require R-values of between R-15 and R-20, depending on region. The courthouse roof, which consists of 16 individual roof components, has R-values of up to R-50.

The second element is a 22-kilowatt photovoltaic array that stretches across a 6,000-square-foot section of the roof, enabling the building to generate electricity from the sun. Contrary to the heavy crystalline silicon panels that most people imagine when they think of solar arrays, the PV system installed on the courthouse roof is made of thin-film solar modules that are lightweight and don't require the roof to be reinforced to handle the additional load.

"It's literally a peel-and-stick thing," said Jean Dodd, who managed the project for GSA. "They just roll it out and stick it on."

The 200 solar panels will generate about 5 percent of the building's electricity, enough to power the facility's day care center. That alone will cut the building's electric bill by about $2,400 annually. The heavily insulated cool roof also will result in additional savings, although building managers will need to study energy bills over time to assess the actual impact.

Employees can track how much energy is being generated by the solar panels at any time of the day by viewing a 42-inch television monitor in the courthouse lobby.

The Dole courthouse is one of 72 GSA-managed facilities that are receiving green roofs with Recovery Act dollars. Fifty-four buildings are being topped with solar roof panels. The rest are receiving insulated roofs that repel heat, vegetative roofs or some mix of the three options.

Replacing roofs with more energy-efficient alternatives is a wise use of taxpayer dollars, since it's one of the areas that generates the biggest return on investment, Dodd said.

"Most of your heat escapes from your roof. It's the most vulnerable area of your building," she said.