Allegheny County Executive Dan Onorato today dedicated the green roof on the County Office Building located at 542 Forbes Avenue in Downtown Pittsburgh. The green roof is the first of its kind on a public building in Allegheny County.
“The County Office Building green roof is already saving energy, reducing stormwater runoff, and cutting down on the amount of pollution reaching our rivers,” said Onorato. “We will use the green roof to show residents and businesses how they can employ green infrastructure to benefit the environment and be energy efficient as well.”
Half of the County Office Building’s roof, an area of 8400 square feet, was covered in waterproof fabric, various insulating and water-trapping materials, and soil and plants native to Southwestern Pennsylvania. It features four distinct types of green roofing methods, including mat and tray systems, as well as semi-intensive and intensive systems. Additionally, a vegetative green screen surrounds the cell tower that sits atop the building. Green screens provide many benefits, including an aesthetically pleasing alternative to fencing, improved air quality, and a natural shield in weather. The green roof’s unique design also reflects our region’s hills, valleys and rivers.
As part of the demonstration project, the other half of the roof remains as-is and serves as a control so the County can measure differences between the two sides. Monitors on both halves of the roof collect data regarding temperature, humidity and rainfall. The data will be available online so the public can track the benefits and impact of the green roof versus the normal roof.
The green roof is already providing an insulating effect for the County Office Building, reducing heating and cooling costs for taxpayers. Preliminary results indicate that electricity usage in the building was 35,400 kilowatt hours less in June 2010 than it was in June 2009, a savings of $7000. Additionally, preliminary data for July 2010 show a reduction in electricity usage of 33,600 kilowatt hours compared to July 2009, resulting in savings of $6500. In September, Carnegie Mellon University will begin to quantify the actual temperature differences inside and outside of the building to help determine actual cost savings.
In Southwestern Pennsylvania, an average rain storm can produce two inches of rain in a 24-hour period. Even two inches of rain falling on a roof can result in more than 600 gallons of water rushing through downspouts and into sewer systems. As little as 1/10 inch of rain can cause combined sewers to overflow.
As rain travels over hard surfaces, it picks up and carries pollutants. The large amount of impervious surfaces in urban areas does not allow rainwater to permeate into the soil. Instead, rainwater flows into storm and sanitary sewers, as well as local streams, which are often unable to handle the higher water volumes, causing back up and eventual flooding.
The County Office Building green roof absorbs rainwater, thereby alleviating stress on Pittsburgh’s combined sewer system and reducing pollutants entering the rivers. The roof is designed to capture one inch of rain once it has fully matured. Monitors show that the roof is already capturing 60 percent of rainwater that falls on it based on data collected from a recent rainfall of 1.02 inches.
“We must come together as a community to address the issue of stormwater management, and green infrastructure is a key component,” added Onorato. “Allegheny County government is proud to provide leadership in this area, and our green roof can be used as a model for residents and businesses. In fact, our green roof has already hosted tours for several businesses that are considering constructing green roofs on their buildings.”
Data also show that the temperature of the green roof is 40 to 50 degrees cooler than the control roof, thereby decreasing the “urban heat island” effect in Downtown Pittsburgh. In addition, the green roof is reducing air and noise pollution and providing habitat for birds and butterflies.
Allegheny County worked with the Penn State Center and Pennsylvania Environmental Council to develop a request for proposals to attract a contractor that could develop the green roof. Cuddy Roofing, a women’s business enterprise headquartered in Pittsburgh, was selected as the contractor to perform the initial roofing work and provide the protective layers. Eisler Landscapes, a women’s business enterprise headquartered in Prospect, Pa., planted the roof, and John Buck of Civil & Environmental Consultants Inc. provided the monitoring equipment and protocol. The green roof cost $621,400 and was funded through federal stimulus grants.
Residents can learn more about green roofs and other energy- and water-saving initiatives at the Allegheny Green & Innovation Festival, which will take place from 11:00 a.m. to 8:30 p.m. on Saturday, August 14, at the Hartwood Amphitheater. The free event will celebrate Allegheny County’s evolution to a green economy and feature ways for residents to become more sustainable in their everyday lives. The festival will be a zero-waste event and will include earth-friendly food and product vendors, crafters, green living demonstrations, musical entertainment, and children’s activities.