How Green A Garden Grows: A Conservatory targets a certification trifecta
Pittsburgh is home to what is arguably one of the greenest buildings in the country: the Center for Sustainable Landscapes, a recently completed facility for research and educational programs on the campus of the 119-year-old Phipps Conservatory and Botanical Gardens. The center, known as the CSL, is aiming for a trio of certifications. In addition to LEED Platinum, the project is one of 150 taking part in the Sustainable Sites Initiative—a pilot program intended to encourage ecologically sensitive landscape-design practices. Phipps and the CSL team hope to achieve four stars, the highest rating possible. But they have even bigger aspirations. They are targeting Living Building status, a designation with tough-to-satisfy requirements such as net-zero-energy and net-zero-water performance.
The $12 million CSL is just the latest piece of a multiphase green expansion program that began after the nonprofit Phipps Conservatory Inc. signed a 100-year lease, taking over management of the city-owned garden in 1993. “Phipps had the potential to be more successful and become a national tourist attraction,” explains Richard Piacentini, the conservatory's executive director.
The new management's first capital project was a LEED Silver–certified visitors' reception wing that opened in 2005. The next year it completed two more: a 36,000-square-foot production greenhouse, with a computer-controlled roof venting system, and the Tropical Forest Conservatory, cooled passively with underground earth tubes.
For the CSL, the garden's most ambitious project to date, designers developed a “synthetic solution” in which the 24,000-square-foot structure and its 2.65-acre site work as one, explains Chris Minnerly, principal at The Design Alliance, the building's architect. The building steps down with the steeply sloping terrain and has its long axis oriented east-west to minimize solar gain. Its thermally robust envelope includes a skin of wood reclaimed from dismantled Pennsylvania barns. Photovoltaic panels, a vertical-axis wind turbine, and geothermal wells will satisfy energy needs.
The landscape, which was still under construction at press time, will include water features, native plant materials, and rain gardens. The scheme will do more than merely look good, says José Almiñana, a principal at Andropogon, which did the project's landscape architecture. “It will perform.”
One of the roles the landscape will play is helping the project meet Living Building water requirements. The CSL and its environs will manage stormwater and treat wastewater. It will put these sources to use for toilet flushing and to offset the significant irrigation demands of the conservatory's greenhouses.
A collection of orchids, for example, will be watered with the outflow from sinks and toilets, but only after the effluent is cleansed in a multistep treatment process that includes a traditional septic system and a constructed wetland containing plants such as cattails and rushes. A solar-distillation system will provide final purification.
A separate system will collect rainwater from the CSL's green roof and the roofs of neighboring buildings, directing it to a lagoon where hydrophytes (plants that thrive when submerged in water) will help remove the small amount of impurities found in roof runoff. After UV treatment, the water will be allowed to slowly filter into the ground or will be stored in cisterns for various nonpotable uses.
The lagoon will provide a habitat for fish and insects and, along with the constructed wetland, will transform the normally hidden, workaday processes of stormwater and wastewater management into landscape amenities. These water features are also an example of the “systems thinking” that inspired the project, says Piacentini. At the CSL, “the waste of one process benefits another.”
