In September, students and junior faculty began moving into 123 housing units at University of California, Davis. The six buildings, which overlook a central open space and include 42,500 square feet of ground-floor retail, make up part of the first phase of West Village, the largest net-zero-energy development in the U.S.
Courtesy Frederic Larson on behalf of Carmel Partners
Not that this inaugural class of tenants would have necessarily noticed the achievement. With the exception of photovoltaic-clad sawtooth roofs, Studio E Architects’ design of the four-story mixed-use buildings has much in common with traditional village and campus settings.
Studio E principal Eric Naslund explains that getting to net zero here meant adhering to “the classic, straightforward strategy of reducing loads as dramatically as you can, and including enough generation to meet the reduced loads.” The San Diego–based firm worked with local consultant Davis Energy Group to model the efficiency and power-generation features that would hit zero with the shortest payback period.
To maximize efficiency, the design team focused on the building envelope. Adding a layer of off-the-shelf rigid insulation to the wood-framed envelope dramatically surpassed the standards of Title 24 with little additional expense, for example. Naslund notes that ventilated facades are installed on the south and west elevations of each of the buildings. As with the insulation, “This is the kind of detailing that anybody would know how to do. We used a simple corrugated metal.”
Studio E project manager Tilly Whitehead also points out that windows and balconies on the east- and west-facing apartments include L-shaped shading devices whose blades are precisely sized and angled to prevent harsh morning and afternoon sun from penetrating the interior. Overall, modeling refined the performance of otherwise manifest efficiency solutions.
The energy model did yield some surprises. Originally, Studio E had assumed that it would need to specify solar water heating for West Village, and that rooftop PVs alone could not produce enough electricity to meet demand. But taking a cue from one of its completed projects—High Tech High in Chula Vista, California, a 2011 AIA/COTE Top Ten winner—Studio E created sawtooths and 6-foot-deep southern overhangs to maximize solar exposure. As Naslund puts it, in both West Village and High Tech High, “the roofscape is essentially intended to create a PV opportunity.” And in doing so, there is enough PV coverage for an electric heat pump to provide all hot water. Excess electricity feeds back to the grid, too.
Naslund says that the design team had modeled other roof strategies to less advantageous effect. The UC Davis campus benefits from the consistent Delta Breeze, so introducing natural cross-ventilation via rooftop monitors seemed logical. Yet calculations showed that ventilating the building’s dense, multiple levels would not have diminished energy consumption as much as an entirely PV-clad rooftop would boost production.
Instead, Studio E employed a thermal chimney on a seventh building in West Village’s first phase. It is the central feature of a 15,000-square-foot structure that contains the complex’s leasing office, gym, and community rooms. The mezzanine configuration of the interior “naturally allows all kinds of air movement through it,” Whitehead says. “And because the roof tilts to the south for daylighting, it creates a natural high spot for siphoning away warm air.”