Full Description The design of the Portola Valley Town Center Library redeveloped 11 acres of a surplus public school site into a park, play fields, and three primary Town Center structures: a Library, Community Hall, and Town Hall offices. The original structures on the site were astride the San Andreas fault, which forced their abandonment. The new buildings are arranged around a Town Plaza that terminates a sweep of reintroduced native and pastoral landscape. The Library contains reading rooms, a childrens area, staff office and the Town Heritage room. The Type V, wood frame buildings, are B-2 occupancy with accessory A occupancies. The 15 million dollar project 13.3 million final construction cost was finished in October 2008.
Program and design were driven by an intense public process. Early on, the towns task force established six goals that were used as a metric by the town council, citizenry, and the design team to evaluate design proposals: 1 Take advantage of the beautiful site while preserving open space; 2 Create civic and recreational spaces that are inviting to all ages; 3 Meet the civic, emergency and maintenance needs of the town; 4 Create friendly and service oriented places that facilitate casual meetings; 5 Exemplify the towns rural design ideals that compliment the landscape; 6 Be an extension of the towns low key residences become a living room for the town.
The design reduces the carbon footprint of the buildings. 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. Exterior siding and louvers are salvaged wood, and wood flooring is local eucalyptus. The concrete mix is 70 slag. These and other measures reduced construction carbon emissions by 32.
The Library and Town Hall orient with the long axis east/west. Roof overhangs and exterior louvers provide shading during warmer months. High clerestories opposite double hung windows allow for cross ventilation and allow the buildings to run a night time cooling cycle on cool nights to pre-chill the building mass.
The wood frame buildings are well insulated with dense-pack cellulose insulation. Ground coupled slabs provide thermal mass and some areas have concrete stem walls for additional thermal mass to help moderate internal temperatures. Windows are glazed with high performance glass. Metal standing seam roofs have a Solar Reflectance Index of .29.
Extensive use was made of reclaimed wood 26,000 board feet or 25 of total wood for the entire project. Wood for interior paneling, ceiling slats, counters and site carpentry was salvaged from buildings deconstructed on site. Exterior, salvaged Redwood siding was installed over a rainscreen product that allows air to circulate behind the siding. Sunscreens are reclaimed Alaskan Yellow Cedar. All framing except for engineered joists is FSC certified. Local Eucalyptus was used for flooring in the Community Hall and four Alder trees, cleared during construction, were used as columns in the new buildings.
Concrete, asphalt and masonry materials from the existing buildings were ground up on site and used as backfill and sub base. Roughly 90 of the deconstructed buildings and 95 of new construction waste was diverted from landfill.
Reclaimed wood saved an estimated 32 tons of GHG emissions seven tons by eliminating kiln drying, 25 tons by keeping the wood out of landfill Reference EPAs WARM Calculator. The reuse of onsite and local materials saved 16 tons of GHG in avoided transportation emissions. High slag concrete 50 replacement of Portland cement saved an estimate 55 tons of GHG.
The buildings in the entire project were modeled for temperature as well as energy performance, so when the model showed the Reading Room in the Library getting too hot, shading and thermal mass could be adjusted. The design team tracked carbon emissions and avoided emissions for the project from materials and construction, to operating and site generated energy. A Building Dashboard installed in the Library allows the community to track the energy and water use of the project.
When, in 2003, the Town of Portolas entire complex of municipal buildings was determined to straddle the San Andreas fault and subject to unacceptable seismic risk, the town knew it had to build a new Town Center and Library. Cost estimates put the project at more than five times the annual budget or existing reserves. Local politics indicated that the electorate would not support the 67 vote required to pass a bond of this magnitude.
Fortunately, the Towns citizens shared an educated and enlightened green building ethic and sustainability orientation. A private citizens group was organized to raise the money through private donations. Once citizens saw our green orientation, they wholeheartedly contributed to specific aspects of the project. Sustainability goals were established immediately to increase natural landscape, reduce site coverage, and if at all possible, restore an existing riparian stream that had been buried in a culvert when the school was originally developed. The town council, and the residents who were involved in the workshops were eager to maintain focus on the sustainability aspects of the new structures, and evaluation of locally appropriate energy and material strategies were a part of every work session. Private donations amounted to roughly 80 of the cost of the project, most of which were donated for specific green features. As we developed momentum, those donations allowed us to stretch our goal from LEED Gold to Platinum. The project received LEED Platinum certification in 2009.