There's a movement afoot to make homes greener, but the impact will be limited if only wealthy people can afford them. Start-up ZETA Communities is trying to expand that movement's reach by making market-priced, "net zero" multifamily homes.
In the next two weeks, the San Francisco-based company expects to complete its first demonstration building, a town house in Oakland, Calif. Using a variety of design choices, such as a passive solar design and very efficient windows, the energy load on the town houses will be 60 percent of what a comparable-size traditional building would require. Solar panels meet all its electrical needs.
The Department of Energy and National Renewable Energy Laboratory will be studying performance data on the building.
ZETA Communities can't claim it's able to build net-zero homes--buildings that produce as much energy as they consume--in every locale. But its construction techniques already work in California, according to CEO Naomi Porat, who founded the company last year. It has a pipeline of projects including a 30-unit student apartment project that is projected to cost 20 percent less than current construction methods.
So what's its formula? The company prefabricates multifamily buildings in a factory to save on construction costs. The buildings themselves are very well sealed and insulated, which lowers the heating and cooling load. Also, the company has developed a control system to manage on-site energy generation and keep track of consumers' electricity usage.
"This is disruptive technology in the sense that these net-zero homes at these prices are not possible without a control system that optimizes all the mechanical systems," said Porat.
ZETA, which stands for Zero Energy Technology and Architecture, plans to sell to developers and architects, rather than directly to consumers. ZETA employees take architects' plans and recommend a way to build the home in modular pieces.
For example, ZETA buildings have a single "utility core" where all the wiring and pipes for heating and cooling systems go. The building is constructed in a factory--90 percent complete--and then shipped to its location for assembly. The process is twice as fast and generates half the waste of on-site construction, Porat explained.
The other break from the industry status quo is an in-home controller that manages sensors and the home's mechanical systems--heating, cooling, etc.--and provides consumers with a display of its electricity usage in real time. That sort of feedback system can help a consumer cut electricity use by 20 percent, Porat said.
Its first planned homes will use solar electric panels for on-site power generation and efficient appliances, including air-source heat pumps and heat-recovery ventilators to provide clean air.
Retrofitting existing homes to be energy efficient represents a larger housing stock to work with. But ZETA is targeting new multifamily units, typically in urban areas, because that type of housing also has the potential to make a large-scale impact, said Porat.
"There's a lot of vanity green going on. Unless you do net-zero homes at market prices, it will keep the market to one segment of the population," she said.