Orinda City Hall
This City Hall creates a larger sense of community and connection for citizens and city staff while demonstrating a high level of environmental responsibility: the 14,000 square foot building surpasses Title 24 requirements by 72% (LEED method) and scored 11 out of 10 possible points (one innovation point for exemplary energy performance) from LEED as part of its LEED Gold rating. The new city hall houses public meeting spaces and the City’s administrative, planning, building, and police departments.
The new building is literally a crossroads for the community, re-routing existing paths through its atrium to reconnect neighborhoods above the site to the civic center and downtown below. Enhanced seismic requirements of this essential facility were met by an innovative hybrid structural system that combined wood frame and steel frames anchored with cables allowing the frames to “rock and recover” after seismic events. Construction cost was approximately $8,000,000 as completed in 2007.
This new city hall for a small city in the Bay Area unites departments previously spread throughout the city. An unusual arrangement between the city and a church on the city’s main street allowed for construction of a civic building within walking distance of transit and downtown on a newly created infill site–the church’s backyard.
A covered outdoor lobby cuts through the building, preserving pedestrian routes through the site, and enhancing opportunities for interaction between citizens and staff. Residents can walk through the building from neighborhoods above to the commercial district below. The design responds to the character and scale of the city with simple shapes and durable, civic materials.
This LEED Gold project demonstrates the city’s commitment to environmental stewardship. Strong team collaboration led to the elimination of conventional compressor cooling, unusual for this building type in this climate zone. An innovative mixed-mode mechanical system runs on natural ventilation whenever conditions allow, reducing anticipated energy use by 72% over Title 24 standards (LEED method), and scoring 11 out of 10 possible points (includes one innovation point for exemplary energy performance) from LEED. Occupants are prompted to open windows when the building is in natural ventilation mode.
The design process emphasized climate-based design: the building is shaped to maximize opportunities for natural ventilation and daylighting while minimizing heat gain. Though the narrow site allowed little wiggle room to reorient the building, the longer south wing of the building was rotated several degrees away from the southwest exposure. The upper floor slides out to shade the expansive lower floor glazing. Light metal shading devices have reflective tops that bounce light into the lower floor. A continuous skylight atop the opposite edge of the lower floor balances the light along the uphill side.
A generous clerestory provides openings northern light and ventilation for the administrative offices. The lower floor’s sloped ceiling and light shelves reflect sunlight deep into the building. Automated controls dim electric lights whenever daylighting is adequate.
The building incorporates significant amounts of green materials that reduce embodied carbon including: recycled steel, 70% slag concrete, cork and linoleum flooring, formaldehyde free desktops and casework, recycled glass countertops, and low VOC paints.
The City’s design concept for the site called for filling in a remnant of creek that bordered the site to improve driveway access. Our design preserves and draws attention to the creek – the most significant element of the site’s ecological systems. The north wing of the building turns to look over the creek to the downtown and western hills.
Landscaping was designed to return the site to a pre-development palette of native plants, minimizing the need for irrigation. Sinks with sensors, waterless urinals, and dual flush toilets further reduce water consumption.
The high performance structural system meets the requirements of an essential services facility with four exposed steel frames intended to “rock and recover” after a major earthquake, minimizing repairs to major structural components.
Narrative for “Saving By Design” Awards
This LEED Gold project demonstrates the City’s commitment to environmental stewardship. Strong team collaboration led to the elimination of conventional compressor cooling, unusual for this building type in this climate zone. An innovative mixed-mode mechanical system runs on natural ventilation whenever conditions allow, reducing anticipated energy use by 72% over Title 24 (without renewable energy), and scoring 11 out of 10 possible points (includes an additional innovation point for exemplary energy performance) from LEED.
High performance started with climate-based design. We shaped the building in plan and section to maximize daylighting and natural ventilation while minimizing heat gain. The narrowly restricted buildable area of our site allowed only a slight reorientation of the building away from the hot southwest exposure. The longer south wing is rotated towards the south as far as the site allow so that the building is easier to shade. The upper floor slides out over the lower floor and the overhang and projecting columns help shade the expansive lower floor glazing. Light metal shading devices span between the columns and have reflective tops that bounce light into the downstairs spaces. The thermal mass in the lower floor and retaining walls helps cool the building at night.
The narrow section allows the building to be lit principally with daylight. The roof is divided in section so that a generous clerestory provides northern light and a pathway for natural ventilation to the administration offices to the south. Sliding the upper floor out allowed for skylights on the north side of the lower floor, providing light where the building is buried deep in the hillside. The sloped ceiling and light shelves help reflect natural light from the south deeply into the lower floor. Automated controls dim lights when daylight is adequate.
The building is designed to run on only natural ventilation whenever weather allows. Signs light up to notify occupants to open the windows when the building is in natural ventilation mode. When needed, the indirect/direct evaporative cooling system works synergistically with the building’s natural ventilation mode, since it cools effectively when windows are open, and improves air quality because the system uses 100% outside air. Comfort modeling was used to stretch the limits of comfort zone design temperatures; ceiling fans, controlled by users, extend the range of this zone.
Since this small office building uses relatively little water, we concentrated on conserving water on site. First, we preserved the creek on the edge of the site and directed site drainage from paving away from the creek. Second, landscaping was designed to return the site to a native, pre-development palette of plants, minimizing the need for irrigation. Last, sinks with sensors, waterless urinals, and dual flush toilets reduce water consumption within the building.
The building is the town’s emergency operations center and has a generator to run the building during power outages. Every effort was made to ensure passive survivability: natural ventilation and daylighting as well as load-shedding strategies reduce the size of the generator and the need for standby power.
22 Orinda Way
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