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CASE STUDY:
Portola Valley Town Center

Portola Valley, California

How green is my valley: When a community founded on environmental principles had to move its civic center from an unsafe site, a highly sustainable replacement evolved.

By Sarah Amelar

Though just a few miles west of Silicon Valley’s urban hardscape, Portola Valley, California, has steadfastly retained its rural character, with forested hillsides, country roads and trails, walnut orchards, and meadows of wildflowers. Decades before “sustainable” became a household term, this well-to-do township of 9.2 square miles founded itself on environmental principles, incorporating in 1964 to block massive development and preserve the pristine landscape.

Portola Valley Town Center. Portola Valley, California.
Photo © César Rubio
Portola Valley Town Center. Portola Valley, California

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KEY PARAMETERS
LOCATION: Portola Valley, CA (foothills of the Santa Cruz Mountains)

GROSS SQUARE FOOTAGE: 19,900 ft2 (1,850 m2)

COST: $15 million

COMPLETED: October 2008

ANNUAL PURCHASED ENERGY USE (BASED ON SIMULATION) : 55 kBtu/ft2 (624 MJ/m2), 34% reduction from base case

ANNUAL CARBON FOOTPRINT (PREDICTED): 12 lbs. CO2 /ft2 (56 kg CO2 /m2)

PROGRAM: Library, community hall, town hall, park

TEAM
OWNER: Town of Portola Valley
ARCHITECT: Siegel & Strain Architects; Goring+Straja Architects
INTERIOR DESIGNER: Staprans Design; Pivot Interiors
LANDSCAPE: Lutsko Associates; Carducci & Associates
ENGINEERS: NKF Engineers (civil); Forell/Elsesser Engineers (structural); Rumsey Engineers (MEP); Integrated Design Associates (electrical)
LIGHTING: David Nelson & Associates
ACOUSTICS: Ewart Wetherill
COMMISSIONING AGENT: Rumsey Engineering
ENVIRONMENTAL CONSULTANT: High Sun Engineering
GENERAL CONTRACTOR: TBI Construction Management

SOURCES
STRUCTURAL: 51% FSC-certified framing lumber from Trus Joist Engineered Joists
WOOD WINDOWS: Loewen’s FSC metal clad
GLAZED GLASS: Cardinal’s LoE3-366
METAL STANDING-SEAM ROOF: Metecno-Morin with Valspar coating
PAINT AND STAIN: Kelly-Moore Enviro-Cote (interior); Scofield’s Tintura (waterborne concrete stain)
TILE: Daltile Natural Hues
FLOORING: Forbo Marmoleum linoleum
CARPET TILE: Interface
SEATING & CHAIRS: Green Design Furniture with FSC-wood
LIGHTING: Litecontrol (interior & task); Philips Lightolier; Prescolite LiteFrame; Louis Poulsen, Nyhavn Series (downlights); Architectural Area Lighting (site lighting) Watt Stopper (controls)
PHOTOVOLTAICS Superpower (panels); SMA America (inverters)
CHILLER: Trane, Seer 19
HEAT-RECOVERY VENTILATORS: FanTech
RADIANT SLAB HEATING: components Uponor
GAS-FIRED WATER HEATER: Voyager (town hall & library)
HEAT TRANSFER: Munchkin
DUAL-FLUSH TOILET: Caroma
WATERFREE URINAL: Sloan
LOW-FLOW SHOWERHEAD: Oxygenics

Since then, the town’s progressive Open Space Fund has set aside 1,900 acres (nearly one third its total), unspoiled in perpetuity. So, when the civic center needed rebuilding, “green” concerns held sway.

Certainly Portola Valley’s 4,500 citizens would not consider rebuilding without dire need. But the town hall, library, and community hall, occupying former school buildings, straddled the San Andreas Fault. Built in 1949, without modern seismic codes, the structures were at risk of lethal rupture and collapse in an earthquake. Vacated and sold by the school to the town in the early 1970s, the 11-acre compound provided a “temporary” civic center that grew permanent over time. Finally, its insurers threatened to drop it as a client.

Subsequent trenching analyses identified a viable new site (not immune to earthquake shaking, but removed from the fault and consequent danger of rupture) elsewhere on campus. But the prospect of demolishing good buildings to erect anew remained controversial in this activist community, long averse to waste and deeply committed to open dialogue and consensus.

“For seven years, before approaching an architect,” the citizens and town council held open workshops on this project, says architect Larry Strain, FAIA, whose firm, Siegel & Strain, with Goring + Straja Architects, ultimately won the commission. “As we quickly realized,” recalls Strain, who grew up in Portola Valley, “we had to make beautiful, working structures that also deferred to the landscape.”

Through community charrettes, the architects, with town residents and council members, crafted a master plan. The evolving green agenda focused on reducing the building footprints, restoring the extensively paved campus to its natural landscape, and optimizing local energy, material, and construction solutions. “The greener it got,” says Strain, “the stronger consensus grew.”

Amid redwoods and other native species, the three new buildings, totaling 19,900 square feet, combine salvaged redwood siding with low-slung gabled roofs of standing-seam metal. Deep verandas and sunscreens of reclaimed Alaskan yellow cedar shade generous windows. Keeping most of the original program, with 20 percent less built area, the $20 million project turned the old site into a park and playing fields, while creating a library, a town hall with administrative offices and an emergency operations center, and a multi-purpose community hall with a catering kitchen.

The project is exceptional for its virtually waste-free reuse of on-site materials and ongoing community engagement—from financing and planning through long-term, environmentally exemplary operation.

When cost estimates vastly exceeded annual town budget and reserves (and a bond measure appeared doomed for defeat), a citizen’s group formed to raise funds through private donation. Portola Valley tends to be a wealthy community, but, here, green strategies spurred private giving, with most contributions earmarked for specific sustainable features. Any resistance to the project eventually eroded, with the funds raised in a single year.

“Even during construction, the town kept upping the bar for green innovation,” recalls Strain. “Usually it goes the other way, with green features getting scaled back.” Deconstructing the old buildings and hardscape, the contractors salvaged a spectacular 90 percent of demolition materials. Remilling Douglas fir for new wall panels, ceiling slats, and structural beams, they ground concrete and asphalt into fill for pathways. They even transformed wood-packing crates into trim. The flooring is local eucalyptus, and four Alders cleared from the site became structural columns. Foundations and slabs of 70-percent-slag concrete helped reduce construction carbon emissions by 32 percent.

For sustainable building operations, the architects optimized passive means—orientation, daylighting, cross-ventilation, shading (with louvers), and thermal mass—to allow for low-energy systems. Roof-mounted photovoltaics will supply 40 to 75 percent of the center’s electricity, reducing nonrenewable energy costs by at least 51 percent.

While light and occupancy sensors will boost efficiency, an interactive “dashboard” tracking up-to-the-moment energy usage will help occupants self-monitor. The permanent reopening of a 350-foot-long section of buried creek—a late project addendum—will create a 40,000-gallon rainwater cistern for toilets and irrigation of native landscaping.

The original goal was simply a sustainable project, but the town is ultimately going for LEED Platinum certification. “Maybe five or ten years ago, it was excessively expensive to be very green, but now it’s mainstream,” notes Ted Driscoll, Portola Valley’s former mayor, a leader in this project. “With the price not significantly higher, but lifetime and maintenance costs lower, it’s just a question of commitment to do it green.”

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This article appeared in the July 2009 print issue of GreenSource Magazine.

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