When the old U.S. Post Office in Town Center reopens as the new Rockville City Police Department headquarters this summer, will feature a roof with a field of green.
Officials behind the plan say that a "green roof"—making the police station the first city building topped with plants—will cost more up front for installation and maintenance, but will save the city money in the long-term.
The roof will pay for itself with its many benefits, said Burt Hall, the project manager overseeing the station's construction for the city.
“With the green amenities, including the green roof, we will see sustainable stormwater management, a longer lifespan of the roofing membrane, and a reduction in heating and cooling costs,” said Hall, who could not provide an exact cost analysis of the green amenities. The vegetation that will cover the roof absorbs rain water, protecting the roof from water damage, reducing the need for drainage holes on the ground, and slightly decreasing the need for air conditioning by providing some shade.
A recent study by the American Society of Civil Engineers suggests green roofs are not cost effective but that they are still worthwhile when other benefits are considered. Such benefits include a reduction in the heat island effect. The phenomenon causes urban areas with buildings, roads and other impervious surfaces, instead of vegetation, to be warmer than surrounding areas that are covered in plants. Click the PDF above to read the ASCE report.
While installation costs for green roofs are higher than those of standard roofs, energy savings need to be taken into account, said Mark Charles, Rockville's chief of environmental management.
Charles offered a hypothetical: "Say we spend $14,000 on the green roof and we would spend $10,000 on a typical roof. But with a green roof we spend $10,000 less in energy costs. We know that the green roof is definitely cheaper.”
The green amenities don’t stop at the roof. The annex was designed with large windows to increase natural light, reducing lighting costs.
Using green roofs has become a popular way to treat stormwater onsite, something that is difficult to do on the ground in land-strapped urban area, Kline said. "Stormwater management regulations have become more stringent recently," he said. "The model has changed where it is preferred if the water was treated onsite."
Click the second video above to view a computer animated "flyover" and virtual tour of the project showing the green roof.
The green roof will take the city one step closer to its goal of being “more sustainable and more efficient, Charles said. The broader goal is to improve the city's environment for later generations.
The project falls within the environmental standards set by the city’s 2010 Green Building Ordinance, Hall said. The ordinance places certain requirements on new buildings and redevelopment.
“A lot of people think that cars are the biggest polluters, but buildings actually are," Hall said. "They use more energy."