Harvesting Rain: System Design for Strategic Rainwater Capture

Conserving water through rainwater harvesting saves natural resources, providing water for use in buildings and for site irrigation
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Sponsored by Watts Water Technologies, Inc.
Celeste Allen Novak, AIA, LEED AP

Rainwater is a national and global issue, whether there is too much rain or too little rain. Adapting strategic rainwater collection can conserve this natural resource. Defined in the Georgia Rainwater Harvesting Guidelines Manual, rainwater harvesting, in its essence is the collection, conveyance and storage of rainwater. Rainwater collected from roof surfaces and other above-ground structures is not "recycled water" nor is it "gray water," but an abundant source of fresh water, generally undervalued in the United States.1

This article is about harvesting and integrating rainwater as a strategy to conserve water and save energy. There are many components to a successful rainwater system. These elements should be specified as an integrated system rather than a checklist of assembled pieces. Whether buildings are sited in dense cities, the suburbs or rural environments, rainwater harvesting can be a successful strategy for meeting many green building goals.

Grand Bay Coastal Resources Center: Highlighting Water Conservation

Archeological evidence reveals that for over 4,500 years, humans have lived in the rich biodiversity of the tidal estuary areas of the Grand Bay Natural Estuarine Research Reserve (NERR). The Grand Bay NERR, an isolated reserve on the Mississippi Gulf Coast, comprises some 18,000 acres of marshes, waters and coastal wetlands that are home to several rare plant and animal species as well as numerous commercial and recreational fish species. The land is owned and jointly managed by the U.S. Fish and Wildlife Service and the Mississippi Department of Marine Resources (DMR). Through its research and educational outreach efforts, the new facility supports the NERR's charter to promote stewardship of coastal resources using an integrated program of research, long-term monitoring, training and education.

Image courtesy of Lord, Aeck & Sargent, ©Jonathan Hillyer Photography

A view of the galvanized sheet metal storage tank used for rainwater harvesting at Grand Bay Coastal Resources Center.

A new headquarters building, designed by the Atlanta offices of architects Lord, Aeck & Sargent in collaboration with Studio South Architects, serves as a center for scientists and students to test, observe and document the environment of this sensitive southeastern Mississippi nature preserve. The building was designed to reflect environmental stewardship of water resources. According to David Ruple, manager of the Grand Bay National Estuarine Research Reserve, "In an effort to reflect our environmental philosophy, I feel that it is not only important to do good conservation work but also to demonstrate how we can build and live more sustainably. I believe that the design and materials incorporated into our new facility will reflect that philosophy. We first had the idea of a green building in 2001 as we developed the master plan for the reserve. We were fortunate to receive the support and funding needed to build it as we envisioned. As we live in a very rainy part of the country, we feel it is important to demonstrate good water conservation practices, capturing and using that abundant rainfall on site."

Environmental protection, water conservation and energy savings were important demonstration and educational components of this coastal headquarters. When the oil from the BP spill began to infiltrate the waters of this protected reserve, it became apparent that rainwater conservation was also a practical strategy. Rainwater from the roof is collected in two 6,500-gallon above ground cisterns and used for toilet flushing and for washing salt water from the Center's research boats. As part of the overall water strategy, the building also has dual-flush toilets, low-flow faucets, waterless urinals and native landscaping. In addition, a bio-filtration wastewater system was also installed as an alternative to a conventional septic field. By design, the Center is projected to use 76 percent less potable water and 53.5 percent less energy than comparable conventional buildings and 40 percent less purified water for toilets and equipment washing.

Jim Nicolow, the director of sustainability for Lord, Aeck & Sargent commented, "One of the big challenges when planning for rainwater collection is that it doesn't really fit into the typical division of labor on a design team or a construction site. There is a potential gap between the civil and plumbing engineers and it can get muddy' as to who takes responsibility for the integration of the components. Involving a rainwater system manufacturer in the design process allows for more successful integration of a rainwater collection system."

This headquarters building achieved LEED® GOLD in 2010, a confirmation of the NERR's commitment to the highest principles of environmentally sensitive design, construction and operation.

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Storage capacity designed to collect roof runoff and as part of an integrated design strategy

Section courtesy of Lord, Aeck & Sargent


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Originally published in June 2013