Z-Squared is an example of an office building whose net energy consumption is zero. In addition to being a zero energy building, it is also a zero carbon building. “It’s one of the first commercial buildings in the United States to be designed to a ‘Z2’ energy efficiency goal; that is, net zero energy, zero carbon emissions.”
The building owner, Integrated Design Associates, Inc. (IDeAs), is a San Jose CA based electrical engineering and lighting design firm, that is committed to walking the walk as well as talking the talk when it comes to sustainable building systems. This project is green not only from the numerous features that were included in the building, but starting at the outset by re-using an existing bank building instead of building new. The company makes no mention of attempting for LEED certification for the building, though it is clear that this building has many features that would earn a number of points in the LEED rating system.
The main page of the company’s website has a big diagram of the building section which diagrams many of the building features in more detail. The building roof is covered with photovoltaic panels to generate 30 kilowatts, and it is estimated that the system will generate 56,000 kilowat-hours of power over the course of a year, adequate to offset all of the building’s annual electrical consumption. Of course, efficient use of that energy is another important part of having a completely solar-powered building.
The energy needs of lighting are largely cut through the use of daylighting. The building is not all glass, however: only a few well-spaced skylights are needed to provide adequate levels of lighting through most of the day. Electric lighting includes efficient T8 fluorescent as well as LED lighting under the control of daylight sensors that turn off the lights when adequate levels of daylight are present. They also used high reflectance paint to spread more light around the interior spaces, whether that light comes from electric sources or from daylight.
Occupancy sensors are another basic but effective feature that is used to turn off lights when they are not needed. The building also has a monitoring system installed which will collect data about the building energy performance. This will help both the building owners improve the performance of the operation of their own building, as well as providing information for designers to make even better buildings in the future. Plug loads (computers, appliances and other equipment that is not permanently attached to the building) are also under control to minimize energy waste when those items are not needed. Natural ventilation and sunshading also contribute to improving comfort for the building occupants and reducing the need for mechanical systems to maintain the building climate.
The building is has a 7200 square foot footprint. Some of it is a single story; the remainder is a two-story building. Previous parking lots on the site was removed and replaced with water efficient landscaping. In-floor radiant heating and cooling is connected to a ground-source heat pump system for efficient building thermal control.
Of course, it helps that the company is located in the milder climate of California, rather than a more difficult and more northerly location. But, more importantly, this modest two-story business building shows that zero-energy buildings are not solely the province of meagerly-supplied off-the-grid cabins. Modern businesses can develop buildings that can provide exceptional levels of performance while still meeting their own needs.