C A S E S T U D Y D I e A s Z 2 DESIGN FACILITY t the first conceptual The team needed a fully integrated BUILDING AT A GLANCE design charrette, the design process, in which the differ- design team decided to ent design disciplines and the gen- Name IDeAs Z2 Design Facility 2 target a “Z ” goal — eral contractor make key decisions Location San Jose, Calif. Azero energy and zero carbon — to together to optimize the building as Owner Integrated Design Associates advance the state of green build- an integrated system. For example, (IDeAs) ing and to showcase the low energy carefully designed sun shading and When Built mid-1960s (originally a electrical and lighting design skills state-of-the-art glazing would allow bank branch office) of the client. For the project to be the team to make many incisions Major Renovation 2007 Renovation Scope Skylights, window replicable, the team wanted a low into the roof and concrete walls to walls, upgraded insulation and energy building that uses exist- harvest more daylight. This would glazing, high-efficiency HVAC system, high-efficiency lighting and office equip- ing technology at a reasonable cost reduce the need for electric lighting ment, rooftop and canopy photovoltaic premium. By maximizing efficiency and its attendant energy consump- system, monitoring equipment of building systems before sizing tion, while also providing outside Principal Use Commercial office the photovoltaic arrays to cover the views for building occupants. Occupants 15 remaining loads, the costs were kept Team members collaborated on Gross Square Footage 7,000 to a minimum. specifications for features such Total Renovation Cost $2,521,097 as skylights, accounting for their Cost Per Square Foot $360 Opposite Building-integrated photovoltaics impacts on not just the daylight- are incorporated into the canopy and the Distinctions/Awards single-ply roofing membrane. Using an ing design, but on the architectural, 2010 ASHRAE Technology Award, integrated system rather than panels elimi- lighting, electrical and HVAC design. First Place: Commercial Existing Buildings nated the need for panel structural sup- The result is a sophisticated design ports, which would have required approxi- Virtual Tour www.z2building.com mately 200 roof penetrations. In 2009, that uses simple controls to maximize the photovoltaic system generated more energy performance while providing electricity than the office consumed. an excellent working environment Below High efficiency fluorescent fixtures © David Wakely with8 T lamps in the main studio are mostly within a reasonable budget. The inte- time, since few opportunities exist Less Than Zero usedt a night. The building serves as a living grated design process emphasizes the to make substitutions or to eliminate lab, testing three types of ballasts that are BYAVID D K ANEDA, P.E., A IA; P ETER R UMSEY, P.E., F ELLOW A SHRAE; A ND S COTT S HELL, F ELLOW A IA importance of getting it right the first parts of the design without affecting switchedr o dimmed by daylight and occu- pancy sensors. the whole system. IDeAs Z2 Design Facility was Back in 2005, when the status quo in commercial building design was protected ready for occupation in late 2007. Today, with nearly three years by the pervading belief that green design principles were too expensive to be of energy and occupant comfort practically applied, electrical design firm Integrated Design Associates (IDeAs) data collected, the project dem- onstrates the viability of net zero made it its mission to prove otherwise. It purchased a nondescript tilt-up build- energy buildings. This daylit, well- ventilated low-rise with no gas ing that was a relic of the 1960s and hired collaborators at EHDD Architecture connection is carbon neutral, with carbon offsets purchased to cover and Rumsey Engineers to help turn this 1.5-story former neighborhood bank the embodied carbon of the building materials used in the renovation. branch into a high performing 21st-century building suitable for housing and At less than one-fourth of the energy use of a typical office,1 inspiring IDeAs’ design staff. IDeAs Z2 is one of the most efficient © David Wakely © David commercial office buildings in the 6 HIGH PERFORMING BUILDINGS Fall 2010 Fa l l 2 0 1 0 HIGH PERFORMING BUILDINGS 7 This article was published in High Performing Buildings, Fall 2010. Copyright 2010 American Society of Heating, Refrigerating and Air- Conditioning Engineers, Inc. Posted at www.hpbmagazine.org. This article may not be copied and/or distributed electronically or in paper form without permission of ASHRAE. For more information about High Performing Buildings, visit www.hpbmagazine.org. © David Wakely © David Natural ventilation features include a seriesf o sliding glass doors and windows on the south side of the building that open sloped to minimize any shading on BUILDING ENVELOPE onto IDeAs’ drought-tolerant garden and the rooftop solar panels. bocce ball court. Roof The team factored in solar heat Type Building-integrated photovoltaic gain effects when estimating cooling membrane U.S. The actual measured energy system requirements. The architect Overall R-value R-30 Reflectivity 80 (SRI) use intensity for this building in selected the size, placement and 2009 was 21.17 kBtu/ft2 · yr (with a glass type for the skylights to care- Walls 2 Type 5 in. concrete plus R-19 batts 21.72 kBtu/ft · yr contribution from fully balance the daylight needs with Overall R-value R-19 the photovoltaic array for a net of their thermal impact. The daylight Glazing Percentage Walls 12; Roof 4.3 –0.55 kBtu/ft2 · yr). designers selected a high perfor- Windows mance spectrally selective glass to U-value 0.29 winter night; Daylighting and Views block unwanted heat with a light-to- 0.27 summer day Solar Heat Gain Coefficient (SHGC) 0.31 Daylighting is one of the key strate- solar heat gain coefficient of 2.33. Light to Solar Heat Gain Ratio 2.33 gies for significantly reducing energy The glass allows useful visible Visual Transmittance 63% consumption. Seventeen skylights light wavelengths to enter the Location were installed into the roof to light building, while blocking most heat- Latitude 37.33°N the main studio and the second floor producing infrared and ultraviolet office space. One advantage of the radiation. A photovoltaic canopy original building’s 18-ft high ceiling mounted over the sliding glass doors ENERGY AT A GLANCE was excellent distribution of light and windows on the south side of Annual Total (Site) Energy 21.17 kBtu/ft2 throughout the workspace below. the building provides a classic pas- Electricity 21.17 kBtu/ft2 The skylights are sized to maxi- sive solar shade and protection from Renewable Energy (produced) mize hours of daylight for conditions rain in the winter, while also gener- 21.72 kBtu/ft2 on short winter days. The framing is ating additional electricity for the Net Energy Use –0.55 kBtu/ft2 8 HIGH PERFORMING BUILDINGS Fall 2010 HPB.hotims.com/33325-5 KEY SUSTAINABLE FEATURES Daylighting Skylights, 18 ft ceilings, shading, electrochromic window Renewable Energy Building-integrated photovoltaics HVAC Radiant heating/cooling with ground-source heat pump Plug Load Reduction Energy-efficient office equipment, occupancy-controlled power strips Lighting T8 fluorescent lamps, daylight and occupancy sensors COST ANALYSIS Energy-efficient upgrades Upgraded glass $20,000 Radiant mechanical system $97,500 over traditional system Concrete for radiant floor $38,000 PVs (after rebates and tax $45,500 incentives) Total cost of energy- $201,000 efficient upgrades Design fees related to $40,000 energy-efficient upgrades (soft cost) Total energy-efficient $241,000 upgrades cost including soft costs Construction costs $2,264,607 © David Wakely © David Design fees (soft costs) $256,490 The south side of the building opens onto Building purchase $2,100,000 the courtyard, which replaced the former parking lot. The ground-source heat pump Total gross cost $4,621,097 building. This glass offers the pri- pipes are laid under this area. Photovoltaics Construction cost and $2,521,097 mary views out from the main studio using solar cells are incorporated into a design fees only (not includ- canopy (bottom). ing building purchase) into an entry courtyard. The canopy blocks direct sunlight Estimated premium for energy-efficient upgrades from entering the building during low-angle morning sun, which would Premium on gross cost 5.22% the hot summer. Conversely, as stream directly in, causing glare Premium on construction 9.56% the sun angles lower in the winter, problems. Interior blinds would have and design fees (including direct sunlight penetrates as deep solved the glare issue, but don’t soft costs, excluding build- as 16 ft into the building, warming block the solar heat gain and tend to ing purchase) the concrete radiant floor. remain closed after the glare prob- Notes • Total gross cost is cost before any federal and The east façade houses a window lem is gone. Exterior automatically state government incentives are deducted. wall that was the original entrance operated blinds were considered • Gross PV cost = $568,879 which included all supporting structures and equipment. to the building. This façade posed high maintenance and are expensive. • PV panels only = $233,063. a difficult challenge to the design The solution implemented is an • Not included in the cost are: interest, property taxes, etc., paid during construction. team since it exposed the office to electrochromic window. When 1 0 HIGH PERFORMING BUILDINGS Fall 2010 HPB.hotims.com/33325-7 © David Wakely Replacing the parking lot with drought tolerant landscaping reduces the heat island direct morning sunlight hits the heat gain from entering the building effect and irrigation needs. window, a photocell tuned to con- and reducing the summer cooling trol the glass on detection of direct load.