Just over a year ago, we announced the Dwell Home II Design Invitational with the goal of establishing a model for sustainable home building for the 21st century. Los Angeles residents Glen Martin and Claudia Plasencia offered up their land in Topanga Canyon to serve as the testing ground, and Escher GuneWardena Architecture’s innovative design was selected as the winning entry. After several months of design, permits, approvals, and the like, groundbreaking for the 2,000-square-foot home is set for spring 2006.
Central to the architects’ plan is the inclusion of a green roof. As project architect Bojana Banyasz explains, “Green roofs keep diurnal thermal fluctuations to a minimum, cutting down on radiant heat gain, which translates into savings on the HVAC system.”
Water usage is crucial in a place like Topanga Canyon, so the roof structure will also greatly increase storm-water retention, “eliminating the urban heat island effect,” Banyasz says. “Even a thin (six-inch soil thickness or less) green roof is able to retain as much as 75 percent of the rain falling on it, stored in the plant and soil layer. This results in a more gradual release of storm water into municipal sewers, culverts, or
the rest of the building site, decreasing the effect of erosion. Green roofs reduce the square footage of impervious surfaces created by every new development, which often alter the drainage pattern of a previously natural area.”
The roof will also lessen the environmental impact of building a new house in a less urban setting like Topanga Canyon. According to Banyasz, the roof can “provide nesting space for birds and other animals that can access the roof, as long as native planting is used. This is one of the main reasons why we are really trying to use as many of the plants already found at the site as possible.”
The green roof is also better protected from decay caused by UV radiation, thus lengthening its life and adding up to significant long-term cost savings for homeowners Martin and Plasencia. And finally, while all of the environmental benefits are fantastic, a green roof also provides a simpler pleasure: “It just looks so much better than a regular flat roof,” Banyasz says.
