Net-zero homes are homes that are so energy efficient that the homeowner only has to add a renewable energy source, typically solar, to enable the building to generate as much energy as it uses. Some home builders have found their niche in building energy-efficient homes and have scaled up to building net-zero neighborhoods. This is true in California, partly due to new targets. The California Energy Efficiency Strategic Plan aims to have 100% of all new homes in the state be zero net energy – ZNE, as the state calls it – by 2020.
Net-zero neighborhoods are possible because they can be built in a way that is relatively affordable and also because they do not negatively affect the electric grid. That’s according to research from the Electric Power Research Institute (EPRI). The independent, nonprofit organization, which has offices in Palo Alto, Calif., and other cities, recently took part in a pilot project in Fontana, Calif. The project focused on 20 new suburban homes in a subdivision, called Sierra Crest, built with energy-efficiency features such as LED lights, advanced water heaters, dual-pane windows and more.
Ram Narayanamurthy, technical executive for energy utilization at EPRI, says the research was twofold. One goal was to see whether it would be feasible economically to scale up to a net-zero neighborhood. It was important to look at home buyers who can afford regular homes, not the more upscale, feature-rich custom homes.
“You want to work with real people that are buying homes, not just energy enthusiasts,” says Narayanamurthy, who was also the project manager at Fontana. “These are normal homes, 1,900 to 2,900 square feet, and the U.S. average is 2,400 square feet for new homes.”
The home buyers got a slight price break because they allowed EPRI and the project partners, builder Meritage Homes and the California Public Utilities Commission, to examine the homes’ energy use and grid integration. The homes have all been built, and the first occupants moved in by March of this year.
One of the barriers to buying a net-zero home, much less building a net-zero neighborhood, was cost.
“The cost of PV is a chief concern builders have right now in trying to get to net zero,” Narayanamurthy says. “It does increase the first cost. The question of affordability comes in. If people qualify for a certain price, does it push people out of being able to afford new homes?”
The second goal was to see how the homes would affect the local distribution grid. Narayanamurthy says EPRI is still working with Southern California Edison to measure grid impacts. The homes use solar, which has its own issues with backflow into the grid, but these homes are extremely energy efficient, so there is a reduced amount of peak load that the homes pull from the grid, he says.
“The goal is to find the balance point between energy efficiency and solar,” he says. “When we get to 2020 in California, solar is probably going to be the most prevalent local generation source.”
All 20 of the homes at Sierra Crest have SunPower rooftop solar panels, or will have them completed soon. SunPower is working with Meritage Homes on other net-zero neighborhoods. One that is coming soon is Meritage Homes Encanto in Southern California. Also, at The Cannery, a mixed-use community that The New Home Company built on the former Hunt-Wesson tomato cannery site, residents can upgrade to net-zero living, including with SunPower solar.
SunPower also will provide solar at UC Davis West Village, a net-zero community of faculty and staff housing that will consist of up to 475 homes. Phase one, with 50 homes, is scheduled to be ready in 2018. The homes will be priced at about 80% of the cost of a comparable Davis home, and the community is meant to attract faculty and staff who might otherwise be priced out of the area, according to the UC Davis West Village website.
There are other net-zero neighborhoods in the works, as the California Energy Commission’s New Solar Homes Partnership provides incentives to home builders to construct new, energy-efficient solar homes.
In other states, builders have made announcements about net-zero neighborhoods coming soon. In Colorado, for example, Sustainably Built LLC is building the GEOS neighborhood in the Denver area. Company principal Mark Bloomfield says that once a cost-effective, well-insulated and air-tight home is built, solar is used to offset the heating, cooling and plug loads.
“Air-source and ground-source heat pumps are used for heating and cooling so that the solar can produce the electricity needed for space conditioning, and fossil fuels aren’t needed on-site,” says Bloomfield. “Extensive energy modeling analysis was done to determine the most cost-effective combination of additional insulation and additional solar panels.”
Narayanamurthy says there will likely be more net-zero energy neighborhoods.
“Energy codes have been getting tighter, and new homes are almost twice as efficient as 10 years ago,” he says. “Builders have been doing a good job, so at some point, it’s a matter of just adding solar to get to net-zero. I don’t see a reason or a huge market barrier right now that could stop the adoption.”
In fact, the U.S. Department of Energy (DOE) has certified nearly 1,000 homes that have met guidelines of the DOE Zero Energy Ready Homes program. Also, more than 14,000 homes were certified under the program’s original name, DOE Builders Challenge.
The DOE currently has thousands of homes in the pipeline from builder commitments and expects to certify more homes in 2017. According to the DOE Tour of Zero website, Zero Energy Ready Homes are verified by a third party and are at least 40% to 50% more energy efficient than a typical new home. Most of the homes either already have solar included or can easily be upgraded.
Nora Caley is a freelance writer based in Denver.