GROUP SUSTAINABILITY REPORT 2010
TRANSBAY TRANSIT CENTER, SAN FRANCISCO, CALIFORNIA, USA
The Transbay Transit Center and Tower will create a single hub for all bus and rapid transit services in the San Francisco Bay area. Envisioned as the Grand Central Station of the West Coast, the facility will eventually serve as the northern terminal for a high-speed rail link from Los Angeles. The facility, which will be the size of four city blocks and include a 75-storey offi ce tower, presented the design team with the need for unique sustainability solutions. Adding to challenges presented by the building’s sheer magnitude are a particular focus on transportation energy use in California – which the state has decided is as critical to regulate as building energy use – and the area’s limited water resources. The presence of these combined factors demands the project design and system operations focus on delivering the utmost in sustainable design.
In addition to distinctive challenges, the project provides singular opportunities for creative solutions. A rooftop park above the transit centre portion of the project will include a marsh to retreat wastewater from sinks for reuse in the facility, and thick soil in the park will act as a stormwater retention system. The soil will absorb heavy rain before large tanks collect the water and recycle it back into the building systems.
Other sustainable design features include:
• The building is predominantly a controlled, naturally ventilated facility and part of the natural environment – it offers a waterproof shelter for the user, but only limited parts, such as retail pods, are conditioned. The base building is primarily an “enabling” system for conditioning to be done by tenants.
• Comfort conditioning is signifi cantly reduced by a geothermal system, coupled with a hybrid cooling tower. The geothermal system interfaces with the grey-water storage system, which provides short duration thermal benefi t.
• The design fully embraces variable comfort conditions – an environmentally positive solution. We relax the typical criteria throughout (above and below grade), except for retail areas.
• Daylighting minimises artifi cial lighting for the bus deck, Grand Hall and above-grade retail areas. Lighting is the biggest energy component for the project and daylighting/daylighting control strategies are a key design element.
• Design standards are to be published for retail tenants regarding installation of conditioning and lighting systems. We may elect to limit tenants’ installed lighting density and require lighting controls, and introduce similar design standards for HVAC.
• The overall building (including the roof and park) acts as a shading device and passive barrier for occupants. The facade is simple, with enough physical presence to visually communicate the architectural intent, but providing building shading and remaining open to the air.
• The bus deck is open and unenclosed and does not need exhaust or air fi ltration, and a requirement to mandate low emission buses has been established. The bus waiting area is a sheltered, generally unconditioned area. Large diameter, slowly moving ceiling fans generate signifi cant air circulation within the entire space.
WSP Flack + Kurtz is the M&E engineer, working with design architect and team leader Pelli Clarke Pelli Associates. The team has literally dozens of design consultants including Buro Happold, Atelier 10, Arup, LEED consultant BVM Engineers and executive architect Adamson Associates. The project was secured in 2007, following a design competition, and phase 1 will open in 2017. Project construction value is well in excess of $1 billion.
“ 28 | WSP GROUP SUSTAINABILITY REPORT 2010
The facility will be the size of four city blocks and include a 75-storey offi ce tower.
Transbay, San Francisco
EMBEDDING SUSTAINABILITY
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