Visit the Albemarle County Green Roof Project home page here, where you can see photos and access research data. It is open for tours during normal business hours. For project info, contact Water Resources Engineer Gregor Patsch at: firstname.lastname@example.org. Read the DailyProgress.com articles “County building?s green roof a tourist draw” of 7.16.08 here and “City Hall, police building to install green rooftops” by Seth Rosen of 1.21.08 here>.
The Albemarle County Office Building is a first of its kind demonstration greenroof project to illustrate and evaluate the value of greenroofs. Completed in July, 2005, the roof was replaced as part a scheduled roof replacement. Utilizing two extensive system types, the roof consists of groundcovers like Shale Barrens, Dragon’s Blood, and Blue Spruce, along with 9,000 sedum plants including Jellybean varieties. Albemarle County’s Green Roof Project is supported with funding from the Chesapeake Bay Program through the Virginia Department of Conservation and Recreation via grant agreement number BAY 2004-20-SR.
DailyProgress.com states, “Albemarle officials have found that the County Office Building?s green roof can be up to 38 degrees cooler than adjacent conventional rooftops in the summer and 25 degrees warmer on winter nights, said Greg Harper, an Albemarle water resources manager (January, 2008).”
The first greenroof system type is a modular system of 18″ x 24″ trays that hold the growing medium and plants. The website (see below) states, “The other system growing on the County Office Building covers the roof more uniformly and takes up to two years to fill in. This system utilizes a large area to apply the parts of the green roof system: rubber membrane, root barrier, water retention layer, filter fabric, and soil medium. These are applied uniformly over the roof and plants are then introduced to the soil medium. This system is relatively inexpensive compared to an intensive green roof. This system covers a majority of the roof and is expected to take two years to fill in. Thus far, the roof has filled in well and appears to be on track for full vegetation by roughly July of 2007. Each system type comes with a comprehensive warranty should any problems arise.”The Albemarle County Office Building greenroof is being compared and monitored for stormwater retention, runoff, and quality; and thermal comparisions of: outside ambient air temperature, radiated heat temperature, rooftop surface temperature, roof underside temperature, inside ambient air temperature, and Climate control influence temperature. To this effect, “A 200 gallon plastic tank has been set up to collect rain runoff from approximately 1/6 of the green roof surface area. Runoff in the tank is measured and compared to rain gage data after each storm to calculate the amount of rainfall retained by the green roof. When the data collection process is completed, we plan to find a suitable way to reuse this water (i.e. irrigation)…Thermal sensors have been placed on both the green roof and an adjacent conventional roof to measure and compare temperature data between the two roofs. HOBO data recorders will be used to continuously measure and record (every 15 minutes) a vertical temperature profile on each roof.”