Zero Energy Certified


vital stats

Certification StatusZero Energy Certified
Version of LBC3.1
LocationDavis, CA, USA
Project Area4,100 SF
Start of OccupancyJanuary 2015
Owner OccupiedYes
Occupancy TypeOffice
Number of Occupants11

Project team

OwnerIndigo | Hammond + Playle Architects, LLP
Project ManagerJonathan Hammond
Project RepresentativeSusan Rainier
General ContractorSIRA Contractors Corporation
ArchitectIndigo | Hammond + Playle Architects, LLP
MEP EngineerIndigo | Hammond + Playle Architects, LLP
Energy EngineerAccurate Energy
Electrical EngineerM. Neils Engineering, Inc.
Lighting DesignM. Neils Engineering, Inc.
Specialty ConsultantsPoint 2 Structural Engineers, Inc. (Structural Engineer); Visha Consultants (Soil Engineer); Talbott Solar & Radiant Homes, Inc. (Radiant System Engineer); McProud & Associates (Irrigation Engineer); Repower Yolo (Photovoltaic Consultant)
Key SubcontractorsTalbott Solar & Radiant Homes, Inc.

Photo Courtesy of Indigo | Hammond + Playle Architects, LLP

building systems information

Wall R value and section specificationR31. Double stud 9.25” cavity, dense pack cellulose
Roof R value and section specificationR60. Loose fill cellulose, vented roof deck
Floor R value and section specificationR10. Viega underslab insulation for hydronic installations
WindowsAll windows and sliding glass doors are Jeld-Wen windows, premium vinyl with Low-E 180 glass.
Air infiltration rate and sealing protocol1.9 (ACH-50). Sealing consisted of conventional caulk sealant, plus application of a prototype aerosolized sealant system (UC Davis)

non-mechanical systems

The buildings are laid out so that virtually all the windows face either south or north. The south-facing windows are designed with overhangs that will shade the windows in the summer yet admit sunlight in the winter which will be used to heat the building. Thermal heat sinks are provided to capture the heat from the sunlight in the winter. The large south facing windows will be fitted with insulated drapes that will reduce unwanted heat loss and heat gain. The passive system will be designed so that it will coast through two-cloudy winter days without the use of a backup system. This same system will be utilized to passively cool the buildings in the summer. Ventilation at night will bring in cool night air to cool the heat sinks which will then cool the building during the day. The buildings are designed for natural cross ventilation. In addition to the passive system, a hydronic system will be deployed in the building slabs to provide backup heating and cooling. On the cooling side, the water will be chilled using evaporation and radiation to the night sky. This water will then be stored in insulated tanks and/or in a cooling pond.



System Type: Air-to-Water Heat Pump

Unit Model & Type: Daikin Altherma Outdoor Heat Pump, MODEL EBLQ048BA6VJU1, 4 tons


Unit Model & Type:

4 Haiku 60, MODEL #K3150-A2 (WHITE) on standard length (10.2”) mount & drop tube

1 ISIS # IS010, 10’ (CLEAR ANODIZED) with 6’ extension tube

toilet room exhaust fans

Unit Model & Type: Utilitech, MODEL #7131-01, 3/10 SONES, 80 CFM, humidity sensing white bathroom fan


whole house exhaust fan

Unit Model & Type:

Shutter Mount Exhaust Fan, 30” 4195 CFM @ 0.125”, 115V 4.5 AMPS, by Dayton MFR MODEL #1HBL5, with fan cover 3 5HKW3

Shutter Mount Exhaust Fan, 24”, 2485 CFM @ 0.125, 115V 4.5 AMPS, by Dayton MFR MODEL #1HLB3, with insulated cover #5HK2W

hot water

Bradford White 19-gallon electric hot water heater. Model: #M12OU655


Small diffusing skylights provide adequate light so the electric lights are seldom used. All interior light fixtures are CREE LED, low-energy consuming. There are ceiling-mounted fixtures in the main workspaces and wall-mounted sconces in the hallway and toilet rooms. Exterior fixtures consist of pole-mounted LED’s in parking and site areas, ceiling mounted LED fixtures to occur at doorway entries to the building. All light fixtures come equipped with light sensors, which consist of two types. First, there are photocell detectors located in skylight wells to advise the system when electrical lights can be dimmed or turned off. Secondly, there are motion-detection sensors distributed strategically to measure human activity in most spaces. When activity ceases, the lights are turned off by the system. The picture above is an interior space showing 2’x2’ diffusing skylights. The ceiling mounted LED fixtures are also shown, but not lit, are seldom needed.

user load reduction strategies

The studio and office space have implemented the following user load reduction strategies: ceiling fans, light-sensor equipped light fixtures, operable louver windows, a casual dress code for comfort, an adjustable thermostat, in addition to work computers being turned off at the end of each workday to reduce daily plug loads.

The building is designed to encourage access to outdoor spaces, the outdoor spaces will be provided with shaded benches and tables that will allow for employee breaks and informal meetings to be held outdoors during fair weather.

Photo Courtesy of Indigo | Hammond + Playle Architects, LLP

renewable production systems information

The building is designed to use very little electrical energy, thus a small solar voltaic system will bring energy use net zero. The south-facing shed roof of the addition is designed to accept solar voltaic collectors and solar hot water heaters.


Actual energy use during performance period16,398 kWh
Actual energy produced during performance period20,200 kWh
Net Energy Use-3,802 kWh
EUI13.7 kBTU/sf/yr

project leadership and story of project

Adaptive reuse of a Dairy Queen transforms a midcentury modern hidden gem into a showcase for sustainability. Originally built in 1967, the 1,400 SF restaurant served a generation of families and was a community icon. After business realities forced its closure, architects saw the potential for its transformation into their new office and studio. The challenge: how to complement the iconic form of the Dairy Queen while increasing its area to the necessary 4,000 SF. The answer was to mix mid-century modern with the vernacular corrugated metal buildings found in fruit drying sheds and agricultural structures found along California’s heartland railroads, similar to the one adjoining the site.

The existing Dairy Queen had a 1,400 S.F. kitchen and dining area enclosed under a 2,600 S.F. roof. The building has an interesting “gull wing” roof shape. The site is almost completely paved with ac for parking. Combining the roof area and the ac paving area, the site is currently only 2% permeable. Site drainage is all on the surface and drains to the streets and the railroad tracks. There are two large cork oaks that protect the West side of the building; they are in the railroad right of way but they intended to do everything that we can do to make sure that they were preserved. There is another younger cork oak on the east side of the property. The site is located in a district of the City with many examples of functionally expressive buildings and utilitarian structures, both old and new. The character along the railroad tracks was unique and worthy of fostering as it has a unique charm about it.

Photo Courtesy of Indigo | Hammond + Playle Architects, LLP

design process

Indigo | Hammond + Playle Architects expanded and converted the old Dairy Queen into offices for their architecture firm. The goal was to create a super sustainable passively heated and cooled design studio. They intended it to work within the context and atmosphere of the district of the City by utilizing simple and honest use of building materials, cork oaks, valley oaks, native grass, and the “Midcentury Modern” lines of the old Dairy Queen. They aimed to preserve the spirit of this iconic Davis landmark by retaining the swooping gull wing roofline by repurposing and reimagining the building using sustainable climate adapted straw bale architecture. It was repurposed as a design center on the railroad tracks. There also exists a studio workshop addition to the existing building that is designed as a flexible project space; the design is inspired by the old vernacular shop buildings seen along Central Valley railroad tracks but updated. For example, the south facing shed roof of the addition will accept solar voltaic collectors and solar hot water heaters.

energy systems narrative

Preserving the curved, glued laminated beams and gull wing roof was a must! Climate-adapted design principles are used to harvest energy from the environment through daylighting, passive heating, night ventilation cooling, and thermal storage. The result is a great new office, studio, and workplace using unique building forms and the memory recall associated with them to provide connection to the context and the community. The high-level of energy efficiency, sustainability, and beauty attained in this design serves the community as an important example to look up as it considers plans for sustainable and regionally appropriate growth in the future.

The existing Dairy Queen is extensively reworked to provide 2,800 S.F. of architect office and studios space. A 1,200 S.F. gallery and event space addition with a high ceiling and ample daylight are used for art openings, lectures, workshops, and other community gatherings. Together, the remodel and addition express the architect’s mission to “integrate art, architecture, and ecology in order to put people in touch with the environment, each other, and their spiritual and cultural aspirations”. There is no reliance on pre-manufactured materials and finishes. Instead, the design explores the use of natural finishes, craftsmanship, and artistic expression.

An example is the biophilic, equisetum-inspired columns sculpted by the architect. The climate-adapted design harvests and stores energy from the natural environment, resulting in a building which is passively conditioned over 90% of the time. How was this done?

First, heat gain is minimized through the use of south and north facing windows, shaded with appropriate solar overhands and fins to bring in daylight but without unwanted heat gain. Daylighting with advanced control of the all-LED fixtures further reduces heat gain by keeping electric lighting off while providing a high quality, naturally lit workplace. Next, building walls are super-insulated to R-40 using locally harvested straw bale walls, an agricultural by-product from the valley’s rice crop. Automated louver windows open at night in summer mode, passing cool night air over the culvert pipe thermal storage tanks, pre-cooling them for use the next day. Finally, sophisticated controls operated the building’s natural conditioning system integrating thermal mass, a 1,250-gallon water storage tank, hydronic tubing running through the concrete floors and a backup air-to-water heat pump.

An 11.4 kW photovoltaic system was installed in December 2016. The system is sized to make the building zero net energy positive. The site features native drought-tolerant and edible landscaping and shaded courtyards which extend indoor space to the outdoors for thinking, working, collaborating, and meetings. A solar-powered fountain is featured in the main courtyard.

Photo Courtesy of Indigo | Hammond + Playle Architects, LLP

building commissioning, start up, and optimization

adaptive reuse

Adaptation and reuse of the existing Dairy Queen Building maintained the existing mid-century modern roofline and most of the existing structural system. In addition, some of the existing on-site paving was utilized. The project team reused the aggregate base material under the existing AC paving.

recycled and sustainable building materials

As previously mentioned they retained and utilized the building structure and reused the gravel under the existing AC paving. The design called for the use of super-insulating walls made of straw bales were used to encase the Old Dairy Queen building. Straw bales are locally grown and manufactured from rice straw, an agricultural waste product. Other sustainable material choices included concrete with fly ash replacing cement, and corrugated metal siding and roofing manufactured from recycled steel.