CASE STUDY: UBER MISSION BAY HEADQUARTERS
Smart, Eco-Friendly Technology Campus
“Drawing on its urge to revolutionize the transportation industry, Uber is pushing the frontier with its innovative headquarters in San Francisco’s Mission Bay district. Through a rarely seen integration of building systems, future Uber employees will enjoy the perpetual benefits of a workplace adapting to its occupants.”- ALFATECH
AT A GLANCE
OWNER: Uber Technologies Inc.
LOCATION: San Francisco, CA
SIZE: 440,000 SF
COMPLIANCE: LEED Gold, WELL Silver, Title 24 2013 and 2016, PG&E Savings by Design
SERVICES: Mechanical, Electrical, and Plumbing (MEP) engineering, lighting design, and Technology (low voltage, security, audio/visual)
MEP LEAD: Jeff Fini
ARCHITECTS: Quezada Architecture, SHoP Architects, RMW Interiors
GENERAL CONTRACTORS: Truebeck Construction
Under the auspices of Uber’s thought leadership, the design teams disembarked on a journey to create a new form of workplace. It started with the occupant, whose hub is the “neighborhood,” an island of the open office. Versatile hoteling stations, collaboration spaces, and conference rooms were natural components. An intelligent control system was masked within each neighborhood, gently nudging critical environmental parameters toward increased comfort. The near-invisible air-conditioning systems were designed to frequently respond, cooling the occupant at temperatures closer to that of the skin as compared to the normative systems. Simultaneously, office and cafeteria lighting systems mimicked the circadian rhythm using an attentive balance of daylight, indirect light, and artificial light. Taken together, the expression was a workplace in tune with its environment.
While the inspiration to the design teams was Uber’s mobility services, the premise was Uber’s culture of inclusion, diversity, and encouragement of connection between employees. Because the strategy was instilled from the top-down, all floors of Uber’s Mission Bay Campus were intended to integrate, interconnect, and constantly acclimate. Thus, spatial constraints were released to promote flexibility.
Vertically Integrated Ascent
In summary, the buildings’ eco-friendly features consisted of:
- Two passively conditioned, interconnected atria
- Shaded facade with automated natural ventilation
- Chilled sails and occupant-controlled underfloor air-distribution systems
- High-performance LED lighting with an occupancy driven network-based lighting control
- Graywater reuse and rainwater catchment systems
- Integrated building automation, controls and management platforms
- Full air-side and water-side economizing
- Fuel cells redundantly powering building network operations
- Urban garden
- Solar domestic hot water system
- PV-ready electrical system
Smart, Self-Sustaining Controls
An elaborate IT infrastructure provides the foundation for the buildings technology systems boasting more than 600,000ft of copper and fiber cabling, 20 IT rooms supporting 167kW of network and server capacity. A robust Wi-Fi network distributed throughout the buildings provide secure and reliable wireless connectivity for both end-user devices, building control systems and public guest access to maintain fidelity to the design-intent; these constituted pertinent integration points to the control system. Individual sub-systems communication protocols compiled to the requirements of the Integrated Building Management System (IBMS) architecture enabling the one-platform control-approach desired by the client.
Two 250 kW fuel cells were selected to power campus IT loads in full, around the clock. Consequently, the campus harbored a self-sustaining cloud that could manage the building systems regardless of the status of the normal power grid. Demand-response capability could automatically turndown 15% of lighting power at the request of the utility. The method provided relief for the power grid during certain, pre-designated peak power days.
Passive Before Active Atria
The two-building atria system, perforated with hanging balconies and slab openings, provided above-grade connections between Mission Bay 1 and 2 towers (also known as 1455 and 1515 Third Street, respectively). From the get-go, the atria were delimited as passive environments to encourage occupants’ connection to the exterior environment. This was aided by a radiant heating/cooling floor system coupled with a fan-assisted, automated natural ventilation system. In the event of wind conditions compromising the structural integrity of the operable windows, mechanical ventilation supplies fresh air. Adaptive thermal comfort modeling demonstrated compliance with our client’s expectations by using refined, meshed-geometry computations.
These innate characteristics of the atria equipped the campus with a near-effortless buoyancy vis-à-vis the outdoor conditions; it significantly reduced energy as compared to any active building component. Meanwhile, transitory comfort could be upheld and regulated by the mixed-mode system on a floor-by-floor basis.
Dual-temperature, high-efficiency water-cooled chillers, with condensing boilers were treated as the assumed central plant condition; however, conceptual studies were also undertaken for geothermal heat-pumps and a condenser water heat exchange with the San Francisco Bay. Due to limitations of the site along with permitting concerns, neither of the alternatives were pursued.
Another focal point in the conceptual engineering design was the perception of wind comfort across the proposed campus. Steady-state computational fluid dynamics (CFD) analysis predicted the worst-case wind velocity vectors as a function of elevation above ground. The results informed locations of parapets and trees to shield sensitive pedestrian walkways and building openings from excessive wind forces.
The sleek, integrated design was predicted to offset energy use regardless of season. Efficient mechanical systems and low-energy lighting spurred the preponderance of the energy use reductions. Water conservation stemmed from a discrete system of pipes and basins that collect graywater from lavatories and rainwater from the rooftops, to repeat water use elsewhere. A diminished ecological footprint naturally aggregated from these conditions of the building systems.
Alternate water practices were enabled by collecting graywater and rainwater to a central treatment system. Safe and fully recycled water was therefore available for flushing at all toilet fixtures. The water reduction was predicted to reach 40% over the applicable environmental standard with 2,100,000 gallons of domestic water conserved annually. UV disinfection and on-site generated hypochlorite for chemical treatment were two important features of the water reuse system. The water quality was controlled to the public health department’s accepted values.
Domestic hot water on the order of 10 times the demand of a modern shower was produced by an array of solar thermal collectors. Comprised of 16 individual collectors, the 500 square feet of aperture area supplemented the domestic hot water system. At rated conditions, the system achieved 650,000 BTU/hr of thermal power.
The astute combination of chilled sails and underfloor air-distribution contributed to the lion’s share of the campus’ state-of-the-art HVAC. Effectively, the chilled sails conditioned workspaces to thermal uniformity while the underfloor air-distribution system supplied fresh air to occupants. The strategy relied on tempered chilled water and high-temperature underfloor air distribution. The latter was served by fan-wall type air-handling units equipped with Variable Frequency Drives (VFD) and MERV13 filter frames capable of accommodating carbon filtration for WELL building compliance. The chilled sails were divided into a perimeter condition and an interior office condition. Both were visually equivalent but used two disparate thermal conductors, carbon graphite and aluminum, yielding higher cooling capacity at the perimeters.
The central systems consisted of dual-temperature, chilled water loops with magnetic bearing chillers, variable primary pumps coupled with injection pumps, and full water-side economizing using variable speed cooling towers. On the heating side, condensing water boilers maximized efficiency by exchanging latent heat between vaporized and condensed water originating from the flue gases normally escaping the building energy systems. The full-service kitchen included variable flow-hoods with safe shut-down, and fresh air delivered in tandem with a pollutant control system scrubbing particles from the grease exhaust.
Energy modeling showed that the savings over the industry baseline were targeted to conserve 25% of the energy use, corresponding to approximately 1,100,000 kWh per year. The passive atria were critical energy use reducers by way of its more tolerant interior climate. Effectively the atria act as a double-skin façade system, greatly reducing thermal loads at the south and west building facades. The glazing types ranged from low-shading, fritted glass at office spaces to high visual transmittance glass at transitory spaces.
Erik Elmtoft, PE, MS, LEED AP BD+C
E: email@example.com P: +1.415.403.3073
Erik is an Associate of Mechanical Systems Design at AlfaTech’s San Francisco office. Erik has contributed to innovative design solutions for several construction projects in San Francisco and Los Angeles. Erik is an inaugural member of the ASHRAE Standards Committee 228P: Standard Method of Evaluating Zero Energy Building Performance.