THE GREEN ROOF ON TOP OF THE ALLEGHENY COUNTY OFFICE BUILDING IN DOWNTOWN PITTSBURGH. | COURTESY ALLEGHENY COUNTY

It has cut electricity costs by $80,000 a year.

It can capture an inch of rain in 24 hours.

It can cool a roof by 20 to 50 degrees compared to surrounding roofs.

It serves as natural insulation — cooling the building in summer, retaining the heat in winter.

And it’s become a natural habitat for wildlife, attracting bees, bugs like praying mantises and even hawks.

These are some of the results of the 8,400-square-foot green roof that was built on top of Downtown’s Allegheny County Office Building in 2010.

And it’s an example of what John Valentine, executive director of the Downtown Neighbors Alliance, is pushing to improve the livability of Downtown. He said he’s reached out to the Pittsburgh Cultural Trust and Point Park University — two of the largest real estate owners in the Golden Triangle — to work together to transform the city’s rooftops into vibrant green spaces.

“We intend to get more green roofs Downtown,” he told attendees at the nonprofit’s recent awards dinner. He said new technology has made the roofs lighter atop buildings and more efficient.

“Our organization will be the lead of the green economy of Downtown Pittsburgh,” he vowed.

The alliance is a community-based organization that partners with community leaders through projects and events that encourage residential development, assist small business and promote arts and entertainment. Essentially, it strives to “make the Golden Triangle a better place to live, work and play.”

The green roof on the top of the county office building, located at the corner of Forbes Avenue and Ross Street, was built as a demonstration project and uses four different technologies, which are constantly being monitored to determine efficiency. 

AN AERIAL VIEW, TAKEN BY A DRONE, OF THE GREEN ROOF ON TOP OF THE ALLEGHENY COUNTY OFFICE BUILDING | COURTESY ALLEGHENY COUNTY

One of the goals of the green roof is to reduce what’s called the “urban heat island” — the level of heat in concrete areas.

Carnegie Mellon University students, who have been involved in monitoring the project, have documented a 75% reduction in heat intrusion on green vs. conventional roof sections in cooling the air through evaporation.

There are several green roofs throughout the Pittsburgh area. As an example, 3 Rivers Wet Weather, an environmental nonprofit that aims to improve the region’s water quality, has awarded grants for green roofs on top of the Shadyside Giant Eagle, Hamerschlag Hall on the CMU campus and for a building at 213-215 East Eighth Avenue in Homestead.