Green Roofs - Living Architecture Monitor - Winter 2009 - (Page 8) STRATA AN INTEGRATED APPROACH TO GREEN ROOFS PHOTOVOLTAICS CISTERNS HEAT PUMPS AND RECYCLED WALKWAYS MAKE THE SOUTH FACE ENERGY INSTITUTE’S ROOF IN ALTANTA GEORGIA A MODEL OF WHOLE SYSTEMS GREEN BUILDING DESIGN By Bourke Reeve S outhface Energy Institute is a nonprofit organization located in Atlanta, Georgia whose mission is to promote environmentally sustainable homes, workplaces and communities through education, research, advocacy and technical assistance. Founded in 1978 as a volunteer organization, Southface has grown over 30 years into a diverse organization with a staff of over forty building and environmental professionals. As part of the organization’s research mission, Southface has constructed two buildings which make up their midtown Atlanta campus. The first building, constructed in 1996, serves as a residential demonstration building. The newest building, The Southface Eco Office, was completed in late 2008 and showcases the latest in high-performance commercial building technology. The Eco Office houses the Southface Commercial Green Building Services team as well as training facilities and meeting space. The consumption of water and power used at the building is tracked by Lucid Design’s Building Dashboard System. This close monitoring allows Southface to demonstrate the building’s performance and track it against similar-sized conventional commercial buildings. An extensive green roof from Chicago, Ill.-based American Hydrotech covers a large portion of the roof of the facility and plays an important role in reducing the building’s energy and water use. The green roof reduces stormwater runoff and assists with reducing the urban heat island effect. As well the green roof reduces the building’s cooling load by significantly lowering the roof surface temperature below that of a conventional roof. The roof system is installed in an inverted roof membrane assembly configuration: the membrane under the green roof is fully adhered to a sloped, concrete composite roof slab supported by a long-span exposed architectural metal deck that also serves as the finished ceiling for the offices below. This system protects the waterproof membrane from physical and uv damage. The J-DRain green roof drainage system drains water off the roof and into an underground site cistern. Other features of the green roof include: walkway squares made from twice recycled rubber, sedum plants and native vegetation and solatubes. The solatubes capture sunlight on the rooftop and redirect it down a reflective tube into interior spaces, reducing artificial lighting needs during the day. The roof deck is lp Weatherbest; a composite product made from high-density polyethylene (hdpe) and post-industrial recycled wood floor, and was donated by BlueLinx. A 6.4 kilowatt photovoltaic (pv) array donated by BP and installed by One World acts as a cover for the rooftop deck while at the same time generating power for the building. The pv array was salvaged from a nearby gas station decommissioned by bp. This type of material reuse strategy was used whenever possible on the entire project. Also on the roof of the Eco Office are five 16 seer heat pumps that heat and cool the building below. An evaporative mesh sprayed with captured rainwater creates a micro-climate around the heat pumps, which can increase hvac efficiency by 15 to 20 percent at peak demand. 8 LIVING ARCHITECTURE MONITOR WINTER
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