Building a Zero-Energy Commercial Office

Aug. 1, 2007
The Z2 Design Facility is attempting the impossible, bringing the zero-energy building to life

When Integrated Design Associates (IDeAs) Inc., a consultancy that provides electrical engineering and lighting design services out of offices in Colorado and California, bought a former bank building for its new San Jose, CA, operations, it saw immense potential. The opportunity was ripe to bring a concept that so many had talked about and so few had attempted - a zero-energy building - to life. "We felt we should walk the walk, not just talk the talk," says David Kaneda, principal, IDeAs, San Jose, CA. The goal was a building with net zero energy and zero carbon emissions (or a Z2 building).

The project was planned 2 years ago, when global warming was hardly big news. "CO2 and carbon emissions were not at the forefront of design like they are now," Kaneda says. "We took a left turn, and I was really nervous about it. In the meantime, the whole world took a left turn and followed along in the direction that we ultimately went." The original plan was to achieve a LEED Platinum rating from the Washington, D.C.-based U.S. Green Building Council (USGBC), but when Scott Shell, principal, EHDD Architecture, San Francisco, threw out the possibility of turning the IDeAs headquarters into a net-zero-energy building, the idea appealed to Kaneda, who has built a practice on the study of energy and lighting. "What [Shell] was talking about is really our sweet spot," he explains.

An integrated design team spent countless hours discussing building systems and features, calculating electrical loads, and weighing the costs and trade-offs of equipment and design strategies. Too many skylights would reduce the insulating capabilities of the roofing system; not enough daylight would mean too much dependence on the electrical lighting system. The renovation would have to cut energy consumption as much as possible - everywhere it was possible. All unavoidable energy that is necessary to run the business will be provided through on-site power generation. "If we had designed a traditional building, we would have needed a roof that [was] twice as big as the roof on the building to put enough photovoltaics on it and call it a zero-energy building," says Peter Rumsey, principal, Oakland, CA-based Rumsey Engineers Inc. While the building will be connected to the utility grid, the hope is that, when the facility is completed and occupied this month, the only things the utility will provide are energy storage and a back-up plan. 

The IDeAs headquarters building started out as a 7,200-square-foot, 1960s tilt-up facility that, when purchased in August 2005, had virtually no windows. Not surprisingly, many had labeled it as "the world's ugliest building." With a vision for the ultimate environmentally friendly office and a lot of hard work, the facility's remodel will prove to many that the quest for net zero energy is not without merit. Estimates for the IDeAs Z2 Design Facility in terms of energy use are approximately 56 mWh of energy per year (43-percent below the 2005 California Title 24 energy requirements and about 60-percent below the ASHRAE 90.1-1999 requirements).

The USGBC reports that the building sector is responsible for almost half of all greenhouse-gas emissions in the United States. Without change, the amount of emissions attributed to buildings will continue to rise dramatically over the next 2 decades. "We're going to need a lot more zero-energy buildings and a lot more integrated thinking," says Shell. Commercial buildings can reduce greenhouse-gas emissions dramatically: The Z2 Design Facility is proof.

Check out some of the features of the Z2 Design Facility in San Jose, CA ...

Dimming ballasts, while less efficient than high-efficiency standard electronic ballasts, are still beneficial. They can start harvesting energy as soon as any daylight is introduced and are less obtrusive when light levels change rapidly. 
Producing chilled or hot water for the radiant slab and dedicated outside air handler, the electric water-source heat pump has a cooling energy-efficiency ratio (EER) rating of over 19. 
Occupancy sensors control lighting in most of the building, including restrooms, the kitchen, the conference room, utility rooms, and even exterior lighting -  the only exception is the studio. Some sensors are manual on and automatic off, so lights are only turned on when occupants want them on. 
Electrochromic glazing, or electronically tintable glass, is used in the east storefront of the studio space. It can reduce direct sunlight transmittance from 62 to 3.5 percent and reduces the solar heat gain coefficient from 0.48 to 0.09. Controlled by a low-voltage controller, the glazing has many advantages over blinds. 
While desktop computers use more energy, laptops with enough memory to support business needs are not cost effective at this time; however, IDeAs is replacing all CRT monitors with LCD flat-screens that use approximately half the power. 
The roof membrane integrated photovoltaic system is lightweight and does not require ballast, special support structure, or structural penetrations. Its solar cells have the highest efficiency (20 to 21.5 percent) of any commercially produced PV cell. The BIPV will supply 100 percent of the building's net energy use. 
Carefully sized skylights have been installed in the main studio and on the second floor, and provide an average of 111 footcandles at solar noon in summer and 40 footcandles at solar noon in winter. This daylighting strategy will reduce electric light consumption and HVAC loads, as well as provide superior light quality. 
Using water to provide heating and cooling is more energy efficient than a forced-air system. A topping slab contains cross-linked polyethylene radiant tubing. 

Copiers, plotters, and printers continue to use power in standby or sleep mode. After hours, IDeAs' security system will automatically turn off circuits supplying this equipment when armed and turn on circuits the next day when disarmed. 
Panelboards using a power monitoring harness will track the performance of the building on a circuit-by-circuit basis; this will allow monitoring of each component of the HVAC system, each lighting circuit, and each receptacle circuit. 
Because the warming element on the coffee pot remains on all day (and sometimes all night), the company is switching to a single-cup coffeemaker. The old coffee pot and a thermos will be used for large meetings. 
When CO2 levels above 800 ppm are detected, the DOAR kicks in to manage indoor air quality. Chilled or hot water supplied by the heat pump to the air handler conditions the air delivered to the space. 
As power flows through the wiring, all circuits lose small amounts of energy through resistance. After performing a cost analysis, the decision was made to upsize all branch circuits carrying large continuous loads to reduce wiring losses (this also reduces cooling loads). 

Jana J. Madsen ([email protected]) is managing editor at Buildings magazine.

Voice your opinion!

To join the conversation, and become an exclusive member of Buildings, create an account today!

Sponsored Recommendations

Decarbonization 2024: How Digital Tools Minimize Your Carbon Footprint

Discover the untapped potential of digital electricity infrastructure in revolutionizing building electrification and decarbonization, unlocking a sustainable future while reducing...

Building Security & Technology Series: Webinar 3 - Proptech

Date: May 22, 2024Time: 1:00 PM EDT / 12:00 PM CDT / 10:00 AM PDT / 5:00 PM GMT Duration: 1 Hour eachGold Sponsors: Genetec, ISS, PrometheusSilver Sponsors: Eagle Eye Networks...

Building Security & Technology Series: Webinar 4 - Lessons Learned

Date: May 29, 2024Time: 1:00 PM EDT / 12:00 PM CDT / 10:00 AM PDT / 5:00 PM GMTDuration: 1 Hour eachGold Sponsors: Genetec, ISS, PrometheusSilver Sponsors: Eagle Eye Networks,...