AIA/COTE Top Ten Green Projects

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Portola Valley Town Center

This photo shows the community hall from the library.
Photo credit: © Cesar Rubio, courtesy of Siegel & Strain Architects


  • Location: Portola Valley, CA
  • Building type(s): Other, Park, Assembly, Public order & safety, Library
  • New construction
  • 19,900 ft2 (1,850 m2)
  • Project scope: multiple buildings
  • Suburban setting
  • Completed October 2008

The Portola Valley Town Center replaced three town structures—a library, community hall, and town hall—that sat on top of the San Andreas fault. The new project, set on a surplus public school site, replaced these buildings and turned the old site into a park and play fields. The library contains reading rooms, a children's area, staff offices, and a room devoted to town heritage. The town hall houses the administrative offices; building, planning, and engineering departments; and the town's emergency operations center. The community hall provides a large divisible multi-purpose room, two activity rooms, storage, and a catering kitchen.

The public was very involved in the design process, and a task force established six goals that were used as a metric by the town council, citizenry, and the design team to evaluate design proposals.

  • Take advantage of the beautiful site while preserving open space
  • Create civic and recreational spaces that are inviting to all ages
  • Meet the civic, emergency and maintenance needs of the town
  • Create friendly and service-oriented places that facilitate casual meetings
  • Exemplify the town's rural design ideals that compliment the landscape
  • Be an extension of the town's low key residences and become a "living room" for the town

This project was chosen as an AIA Committee on the Environment Top Ten Green Project for 2009. It was submitted by Siegel & Strain in Emeryville, California. Additional project team members are listed on the "Process" screen.

Environmental Aspects

The new town center weaves together oak woodlands, playing fields, and new buildings into a civic center that meets the town's goals to compliment the natural beauty of the landscape in the greenest way possible.

The seismically unsafe, old town center was deconstructed; materials from the buildings were reused as beams, paneling, countertops, and structural fill. The new buildings are 20% smaller. The exterior siding and louvers are salvaged wood, and the wood flooring is local eucalyptus. The concrete mix is 70% slag. These and other measures reduced construction carbon emissions by 32%.

Proper building orientation, daylighting, natural ventilation, sunshades, and thermal mass reduced overall energy use and allowed for smaller mechanical systems. Small, efficient air-conditioning units pre-cool make-up air and eliminate the need for full air conditioning. The 76 kW photovoltaic system supplies 40% of the electricity used by the building; nonrenewable energy costs are reduced by 51% and operating carbon is reduced by 76.2 tons per year.

A section of buried creek, now exposed to daylight, defines the fourth side of the town center courtyard. The abandoned culvert will become a cistern for storing 40,000 gallons of rainwater.

Owner & Occupancy

  • Owned and occupied by Town of Portola Valley, Local government
  • Typically occupied by 22 people, 40 hours per person per week; and 1,673 visitors per week, 2 hours per visitor per week


Design charrette, Green framework, Simulation, Green specifications, Contracting, Commissioning, Performance measurement and verification, Operations and maintenance, Open space preservation, Wetlands, Indigenous vegetation, Stormwater management, Efficient fixtures and appliances, Drought-tolerant landscaping, Wastewater treatment, Massing and orientation, Insulation levels, Glazing, Passive solar, HVAC, Lighting control and daylight harvesting, Efficient lighting, On-site renewable electricity, Adaptable design, Durability, Benign materials, Salvaged materials, Recycled materials, Local materials, C&D waste management, Connection to outdoors, Daylighting, Natural ventilation, Ventilation effectiveness, Thermal comfort, Low-emitting materials, Indoor air quality monitoring

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Last updated: 4/13/2009

Our thanks to the ENERGY STAR program of the U.S. Environmental Protection Agency, and to the U.S. Department of Energy, and to BuildingGreen, Inc. for hosting the submission and judging forms.

For more information about the AIA/COTE Top Ten Green Projects, contact AIA/COTE. For help on how to use this Web site, contact .

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