EMORY UNIVERSITY, Atlanta, has been a champion of sustainable-design practices for decades. After building sustainable health-care and academic buildings, the university established its Office of Sustainability Initiatives in the fall of 2006. The responsibilities of the office include creating a healthy living-learning-working community, expanding education and research, operating and building healthy university structures, and supporting leadership and participation. The office’s initiatives range from restoring the forested-campus vision of Emory University’s original landscape designer, Henry Hornbostel, to reducing the university’s waste stream by 65 percent by 2015. As part of its mission, the Office of Sustainability Initiatives already has implemented a free shuttle bus that travels through campus using alternative fuels. It also has introduced locally grown, sustainably produced food into the campus food service.
Emory University is supporting the city of Atlanta’s green-building strategies. Currently, all new city buildings are required to achieve a LEED Silver rating from the Washington, D.C.-based U.S. Green Building Council. According to the Cambridge, Mass.-based Sustainable Endowments Institute, Emory University has more square feet of LEED-certified buildings than any other campus in the U.S. University trustees have committed that all new construction will at least attain LEED Silver certification. The university intends to achieve LEED Gold with its new first-year-student residence halls—Ignatius Few Hall and Lettie Pate Whitehead Evans Hall. The residence halls’ unique rainwater- and condensation-reclamation systems will provide water to flush all toilets.
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HARVESTING WATER
Ignatius Few Hall and Lettie Pate Whitehead Evans Hall currently are being constructed near Emory University’s first sustainably designed residence hall, Turman Hall, and are part of a plan for a high-performance freshman housing complex. Few and Evans Hall will total 111,000 square feet (10312 m²) and feature large smart classrooms, multipurpose rooms, lounges, studies and a demonstration kitchen. When Atlantabased Newcomb & Boyd was selected to be the engineer of record in 2006 for the new 293-bed residence-hall facilities, the drought conditions affecting most of the Southeast weighed into the design process. Methods of reclaiming water without having to treat it at a municipal facility are becoming more prevalent in the U.S. In particular, the concept of reusing rainwater and condensation waste from air-conditioning equipment for domestic purposes in commercial buildings is increasing in popularity.
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Emory University is a pioneer of such systems in the academic world. Collecting rainwater and air-conditioningcondensation waste provides the versatility to deliver service even under drought conditions. Because both sources will flow to an 89,000- gallon (336865-L) reservoir that is installed below grade in front of the buildings, there is sufficient storage volume to supply the estimated 2,170 gallons (8214 L) needed to flush all toilets on a daily basis even when Atlanta experiences no rainfall for several weeks. The major components comprising the systems have been designed by the civil and plumbing engineers. Rainwater will be harvested from the canted, clay-tile rooftops and from the site via conventional downspouts and gutters.
Downspouts will empty into exposed brick runnels that are a visible part of the landscape design. The brick runnels will carry the water down a slope alongside a main pedestrian route, and the water will spill over a stone weir into a bioswale. The bioswale filters and slows the flow of storm water before it reaches the cistern below. Condensation-waste reclamation significantly augments the unpredictable nature of rainfall accumulation by as much as 300,000 gallons (1135500 L) annually, most of which is collected between May and September. Condensation from the buildings’ air-conditioning equipment will be collected through gravity drainage and conveyed through an underground piping system. In lieu of a traditional above- or below-grade singular tank to store captured rainwater and condensation, the system features a series of high-strength plastic chambers installed in rows below grade.
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This system of chambers will serve a dual role: It will act as an underground cistern and as storm-water management for the site. On one end of the array, excess storm water will flow over a weir into an outlet-control structure that is connected to the county storm sewer. On the opposite side, water will spill into a manhole. The manhole serves as a lift station to pump the captured water to the building and transport the water through a filtration and sanitization system in the basement mechanical room. After the water is properly filtered, chlorinated and dyed green or blue to alert the user the water is non-potable, it will fill a holding tank before being distributed by a booster pump to water closets throughout both residence halls. This process can occur autonomously because of two motorized valves and float-level switches in the manhole and holding tanks. The manhole pump and treatment equipment will be controlled and monitored by a microprocessor master control panel. With respect to system complexity and serviceability, the booster pump has its own controls and is not electronically connected to the remainder of the system. Keeping the booster pump separate from the rest of the system affords the ability to perform maintenance or repair on the treatment-side of the system while still supplying water to flush toilets.
CHALLENGES
Although the idea of reusing available water sources for processes usually performed with municipally supplied water initially may seem simple, the idea quickly can become complicated in practice. Critics of environmentally conscious design may argue that these systems increase the complexity of a building, thereby neutralizing any benefits. A system of many parts, however, does not mean it is inherently problematic. If designed and implemented properly, intricately planned systems can operate efficiently and smoothly; the idea is to make buildings more self-sustaining with less maintenance. The traditional approach of gathering water from a stream or lake, treating and transporting it on a massive scale, and paying for the network to support the process is going to be transformed by having self-reliant buildings give back to the matrix of utilities that supply them. The new residence hall complex at Emory University is one such endeavor.
W. SCOTT King is a plumbing engineer with Atlanta-based Newcomb & Boyd. He is an engineer-in-training and a member of the American Society of Plumbing Engineers, Chicago. He can be reached at [email protected] or (404) 730-8499.
