Green roofs and regenerative design
Paul Kephart’s vision for regenerative design: Living architecture that does many things at once
Fabric Architecture | September 2011
By Frank Edgerton Martin
In every generation, some of the most innovative thinkers in landscape ecology come from outside the formal design disciplines. Paul Kephart, founder of Rana Creek Studio in Monterey, Calif., is one such inventor. Originally a landscape painter, Kephart is now a leader in the emerging fields of integrated design and “regenerative” architecture.
Kephart is widely admired by architects because his green roof projects function on many levels. All of Rana Creek’s projects reflect an integrated design process that achieves multiple benefits for building and site performance such as passive ventilation, blackwater recycling for irrigation, and improved habitat. “Historically, we have looked at buildings as a series of ‘green measures’ mandated by LEED,” Kephart says. Yet this process tends to foster a “check the box” approach rather than holistic solutions and concern for site-specific and regional issues.
For Kephart and his Rana Creek colleagues, Marie Goulet, Blake Jopling, and Oona Gabercek, regenerative design “doesn’t just offset impacts but increases productivity” in such areas as energy generation and waste management. “In regenerative projects, we look at multiple tools, processes and functions and apply them collectively to the site and structure.” Rather than asking how a building might reduce air conditioning loads or achieve low VOCs, Kephart is asking more daring and connected questions, such as:
- Does the project support the species and pollinators that live there?
- Does it improve the air?
- Does it reuse wastewater and cool the building?
Stories of regenerative design
One of Kephart’s earliest “integrated” projects is the Gap corporate headquarters in San Bruno, Calif.—built 15 years ago with William McDunough + Partners. Not only was Gap one of the first large-scale living roofs in North America, it also pioneered native species selection based on slope orientation, wind speed and direction. Three stories above grade, the designers included a wetland swale for water capture and species diversity—a feature that seems progressive even today.
In Canada, at the Vancouver Convention Center (in collaboration with PWL Partners Landscape Architects Inc.), Kephart’s green roof serves as ecological stepping stones connecting to the city’s lauded Stanley Park. But that is only the beginning of the benefits. Blackwater, (contaminated water from toilets, sinks and cleaning normally destined for sanitary sewers) is cleansed on-site and then reused to irrigate the green roof and to cool the building. This kind of “stacking” of functions marks a new step in restorative design. Kephart explains that these connected systems make economic sense too. “The cooling of the large building saved so much money that the return on investment paid for both the green roof and the blackwater cleansing system.”
At the California Academy of Sciences designed by Renzo Piano with Arup and SWA, Kephart’s green roof has already collected 14.4 million liters of stormwater since opening in 2008. But “the real story,” he says, “is urban biodiversity.” With bees, beetles, spiders, gnats and many other flying insects, the new green roof is the most species-diverse setting in all of Golden Gate Park. “Typically the flying pattern of insects is interrupted by streets and buildings,” Kephart says, but a site-appropriate planted roof can act as a bridge to connect surrounding natural communities. Fifty plant species native to San Francisco are spread over 14,400m2 of roof with four steeply sloped domes that evoke the rolling hills of the Bay Area.
In nearby Emeryville, Calif., Kephart helped to make a new West Elm store into a billboard of regenerative design. Clearly visible to more than 200,000 daily drivers on the Bay Bridge, the furniture store’s species-rich living roof helps to insulate the building and includes an integrated irrigation system that reduces their water usage by up to 25%. Along with providing an urban natural habitat for butterflies, birds and insects, the roof houses a large solar power system that offsets 10 to 15% of the building’s energy use.
Rana Creek also works in many inner-city neighborhoods. At Council District 9 in South Central Los Angeles, Kephart helped Paul Murdoch Architects and Pamela Burton and Company to create a new “village hall” on an abandoned auto lot. This city-owned building incorporates a 26,530 liter underground cistern, a stormwater collection pond, green walls, parking lot bioswales, solar panels and a large roof garden designed as a park. Ultimately, Kephart argues that “resiliency” means not only locally-based and connected systems, it also applies to human communities, to the ability of people to gather and to build a shared sense of neighborhood.
Optimism for a restorative economy
Kephart is an optimist about the future of restorative design and its impact on the economy and society. “Think of all the great opportunities for new materials, monitoring and infrastructure,” he says. As we move from an extractive to a “restorative” economy, Kephart believes that we will create entirely new kinds of jobs, industries and academic training. “We know how to manage and record data relating to energy use, water quality and the waste stream,” he says. But what we lack is “a multifunction approach to modeling for optimal performance…how they support the mechanical and plumbing of a structure.”
After centuries of carbon-based industrialization, Kephart believes that we are about to flip to systems that are much more decentralized, regionally responsive and self-renewing. As a Californian, Kephart is especially concerned about planning for catastrophes such as earthquakes, fire and other calamities. When energy, water and food all come from distant sources over complex networks, the danger of collapse is increased. By harvesting water on-site, growing food in cities and generating electricity close to home, society’s overall infrastructure is much more flexible and resilient. He argues that we need to build such fine-grained “mosaics of infrastructure within the bigger grid.”
In Kephart’s vision of the future, Americans will not all be living on some green version of Frank Lloyd Wright’s Broadacre City. Instead, he believes that urban form and density must be a response to local conditions—that there is no one urban model for diverse ecologies. But soon communities of all kinds will need to shift from highly-consumptive to locally-based regenerative building—something that innovative designers, product inventors and investors are fully able to achieve. For Kephart, the challenge is rethinking past assumptions. “There’s so little time and so much to undo.”