Energizing houses with the power of the sun
At the end of the year, the homeowner pays nothing in energy costs, other than the monthly fee required to connect to the grid.
Solar-powered homes are no longer just a thing of the future. They are here. Zero-net-energy homes produce as much energy as they consume, allowing the home’s net energy bill (energy credits minus energy usage) at the end of the year to be zero. These homes are grid-tied; excess energy from the solar panels on sunny days is sent to the electric grid and credited to the homeowner’s electric bill.
On cloudy days, electricity is drawn from the grid and the energy use is deducted from the homeowner’s credit with the electric company. At the end of the year, the homeowner pays nothing in energy costs, other than the monthly fee required to connect to the grid.
To qualify as a U.S. Department of Energy Zero Energy Ready Home, a residence must meet the minimum requirements specified on the DOE’s website, be tested in accordance with Home Energy Rating System Standards by an approved verifier and meet all applicable codes.
In addition to the low-cost benefit, ZNE homes are comfortable and quiet.
“ZNE homes have much better insulation, air sealing and windows than a typical home,” explains Ryan Shanahan, senior green building consultant for Portland, Ore.-based Earth Advantage. “This lends itself to a home that is a lot more comfortable year round and noticeably quieter. Another huge benefit is air quality. In order to reach ZNE, these homes typically require a heat recovery ventilation system. These exhaust stale air from bathrooms and kitchens while providing fresh, filtered air from outside to bedrooms and communal living spaces 24 hours per day.”
Joe Emerson, co-founder of the nonprofit Ecological Development Foundation, agrees: “Comfort is by far the biggest benefit of a zero-energy home, aside from the obvious energy savings. ?ZNE homes are built to a higher-quality standard and are built to last.”
ZNE buildings are growing in popularity across the country.
“Savvy homebuyers want homes that are resilient to changes in energy pricing and extreme weather,” Shanahan states. “They like the idea of the all-electric house. Surplus power generated in the peak sun hours can be fed back into the grid, stored in a home battery or power up an all-electric car.”
High-performance home builders and designers are capitalizing on this mind-set and “selling the dream” of a truly sustainable lifestyle to an eco-conscious buyer or a technology-driven lifestyle to someone who always wants the latest and greatest Apple product, he adds.
Zero-energy homes are being built in almost every state, Emerson says, primarily because they have so many advantages over a similar code-built home: they save energy, have no net carbon emissions, are more comfortable to live in, are more durable and their cost of ownership is lower.
California stands out as having more buildings that are closer to ZNE than any other state in the nation. Its building energy efficiency standards (Title 24) are some of the most progressive in the country and are constantly moving toward increasing levels of high energy performance in new buildings, reports the California ZNE Homes website. The state is continuing its leadership by:
• Setting goals to achieve ZNE by 2020 for all new residential buildings and by 2030 for all new commercial (and 50% of existing commercial) structures;
• Providing technical assistance and incentives for owners and design teams through programs such as “California Advanced Homes” (residential) and “Savings by Design” (nonresidential);
• Demonstrating ZNE leadership in state buildings (per Governor’s Executive Order B-18-12);
• Investing in new technologies and research for increased energy efficiency; and
• Providing incentives for rooftop solar photovoltaic systems for new homes that meet the highest efficiency standards through the New Solar Homes Partnership.
“It’s safe to assume that other states will follow California’s lead,” Shanahan says. “The installed cost of solar panels keeps coming down as the efficiency improves and state energy codes continue to push toward built-in higher levels of energy efficiency.”
However, not much is being done to push zero-net-energy homes in other areas. “The real push is coming from small builders and contractors throughout the country, such as builder and developer Transformations in Townsend, Mass., who are pioneering the construction of zero-energy homes,” Emerson notes.
Mechanical contractors can be more involved in the ZNE homes movement in two big ways. “First, work with an energy consultant on how to do it from the design phase all through the build process,” Shanahan advises. “Second, certify the great work you do. Home certification programs lend the same credibility to ZNE claims that consumers are looking for in their organic food, fair trade coffee, etc.”
Of course, proper training in the different technologies is essential.
“Take classes on energy-efficient construction techniques from organizations such as Earth Advantage?,” Emerson encourages. “Learn from your peers who have worked on zero-energy homes, visit sites such as http://www.zerohomes.org/ and take the risk of building one.”
Use your own home as a guinea pig by taking advantage of the programs your local energy utilities offer for energy efficiency, Shanahan says.
“Always start with a home energy audit to find out where you can gain the most bang for your buck, usually air sealing and insulation rather than new windows,” he adds. “Also, look out for ZNE multifamily projects, communities and businesses. The future is bright for energy efficiency and renewable power.”