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Solar Decathlon 2009 | |
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We Can't Ignore Climate Change | |
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Portola Valley Town Center | |
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Green House in Georgia | |
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Portola Valley Town Center If the center looks and feels environmentally friendly, its green roots also run deep. Volunteer committees worked with TBI Construction and Construction Management to keep the project on a sustainable track every step of the way, from demolition through construction and landscaping. In adhering to a strict environmental program and a budget, the architects shrank the overall building footprint 20 percent compared to that of the former facility, to just under 20,000 square feet (1,900 square meters). The library doubled in size, but most other spaces are smaller than in the old building. Fully invested in going green, the town cut out space for nonessential functions, such as art studios, and condensed others, combining two activity rooms into one in order to minimize the building footprint. Still, more people than ever before are using the new facilities and grounds, according to Ted Driscoll, another town council member. Shades of Sea Ranch That the simple array of structures appears more like a summer camp than a civic monument is by design. The architecture is in accord with a local ordinance that encourages buildings "as unobtrusive in the natural terrain as possible," thereby protecting open space and views. The design shows the influence of William Turnbull, the "T" in MLTW of Sea Ranch fame. Turnbull worked from a similar palette of untreated vertical redwood siding and shed roofs, and his architecture, too, defers to its surroundings. Turnbull's influence on the Portola Valley center is no surprise, since several architects on the project had worked for Turnbull at one time or another, including Larry Strain and Jim Goring, partners-in-charge for their respective firms, and Strain's colleagues Henry Siegel and Susi Marzuola. Like Sea Ranch, the Portola Valley Town Center exists in a rarified rural setting. It, too, has a skin of natural wood that will weather to a silvery gray. And it takes the addition step of minimizing the use of new wood. Designing to Conserve Other resources are spared as well. The carefully oriented buildings rely on daylighting and passive heating and cooling to conserve energy, helping the complex exceed California Title 24 energy requirements. A 76-kilowatt photovoltaic system supplies about 40 percent of the building's electricity. In winter, those who frequent the library and offices enjoy radiant heat coming from the concrete slab underfoot. Thick concrete stem walls aid thermal comfort by keeping the south-facing reading areas warm in winter and cool in summer. The concrete has a high proportion of slag, a byproduct of smelting ore. This translates into high performance, low permeability, and lower carbon emissions during construction than conventional concrete. Sunshades minimize heat gain in summer, when temperatures can reach triple digits. Ceiling fans circulate air, making the warm days bearable, and a residentially-scaled compressor-based cooling system takes the edge off the heat without overcooling. And the town keeps tabs on its resource use. Inside the library, an interactive "dashboard" displays energy consumption, and the town monitors its water usage monthly. Rooted in Reclamation Both architects and town council members enthusiastically embraced recycling on a large scale. Contractors reused or recycled 80 to 90 percent of the raw materials from deconstructing the old buildings. They pulverized asphalt from old roadbeds, concrete block, and foundations and used it for site work, as winterization or backfill for pipes and electrical lines. Nothing went to waste. Salvaged beams support exterior sunscreens, and the library ceiling and interior siding derive from former tongue-and-groove roof decking. The contractor even repurposed spare two-by-fours from formwork as interior wood trim on the new buildings. Estimating how far the reclaimed wood would go was challenging, recalls C.R. Hodgson, who was the construction manager with TBI Construction. To determine what could be salvaged from the original structures, the building team crawled around in the attics. All the old wood was sized up and translated to usable linear feet, he says. The contractor carefully pulled the roof off the old building to protect the wood, and located a salvaging mill in Oakland that passed the wood under magnets to remove nails. With buildings that employ recycled materials whenever possible, "trying to write a spec doesn't work," explains Strain, adding that using salvaged wood did not save money on the project. The architect relied on the contractor to locate additional reclaimed wood. In one serendipitous instance, the metal roofing came packaged in 30-foot- (nine-meter-) long wooden crates. "The Douglas fir two-by-fours were in really good shape," recalls Hodgson. The window subcontractor had been eyeing the crates for trim, so Hodgson sanctioned a dumpster dive to retrieve them. The wood was then used to make the neat exterior sills and protruding shading that punctuate south-facing windows. >>> Discuss this article in the Architecture Forum...
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