The Near-Zero-Energy Home: Savvy production builders are turning dream into reality - and winning an edge with customers

Appear in: Solar Today - May/June 2005

For a glimpse of the houses of tomorrow, one need look no further than the work of a few forward-thinking production builders. Combining solar energy technologies with energy-efficient features and energy-saving construction techniques, these builders are constructing houses that generate nearly as much electricity as they consume on an annual basis.

The houses, developed under the U.S. Department of Energy’s (DOE) Building America research program, act as miniature power plants. As a result, the estimated total annual energy cost for houses in the Zero-Energy Home (ZEH) program is approximately 60 percent less than that of similar houses. DOE’s goal is widespread adoption of these and additional features by 2020 in order that a large number of new U.S. houses will be true net-zero-energy homes. With over 500 near-ZEH program houses in nine communities in California, our firm, ConSol, is just beginning to work toward the DOE’s goal. (Access www.buildingamerica.gov for more information.)

California is a good testing ground for building near-ZEHs with renewable energy technology — a “grand experiment” that is beginning to pay off. California has the combination of opportunities and incentives that make near-ZEH communities affordable and marketable: utility “buy-down” programs that subsidize solar technology purchase; net metering, allowing the homeowner to sell unused energy to the utility company and “bank” excess energy credit to offset their usage when the solar system is not generating energy; and, of course, abundant sunshine. The marketability of this package is promising, and proponents hope to replicate California’s success in other areas of the country. Nevada is already moving toward implementing similar building methods.

Constructing the Zero-Energy Home

A key element in designing a near-ZEH is that the house’s overall energy use first must be dramatically reduced through a combination of super-efficient features and advanced construction practices. The use of these energy-saving building methods ensures that the addition of a relatively small photovoltaic (PV) solar system (typically 2.4 kilowatts in capacity) can effectively lower the electricity usage of a house by half or more compared to a typical new home.

For instance, a typical house has 20 percent to 30 percent duct leakage. In a near-ZEH, ductwork is sealed and super-insulated or placed in the conditioned space. Spectrally selective glazed windows reflect the sun’s heat in summer and reduce heat loss in winter. Mechanically designed HVAC systems account for bends and turns in ductwork, register locations, duct length, connections and airflow. Other ways to “tighten up” residential energy consumption include improved ceiling and wall insulation, energy-efficient appliances and the use of fluorescent lighting. All of these efforts are combined in a whole-house approach to designing and building the ZEH.

Once a house has been made super energy efficient, an array of PV modules is installed. Usually located on the roof, the array converts sunlight into direct current electricity, and through the use of an inverter, turns DC into AC electricity to power the house. Many builders prefer building-integrated photovoltaic (BIPV) systems, which are built into the roofing materials. For multiple reasons, mainly aesthetics and to minimize roof penetrations, BIPV systems are a good choice for production houses.

Creating a Market

Why do production builders build near-ZEHs?

Sometimes an arduous entitlement process is eased by jurisdictions if builders build “green.” Another motivation is that building environmentally friendly is the right thing to do. Solar energy’s lack of noxious emissions and ability to reduce a house’s reliance on foreign and domestic fossil fuels reap tangible benefits — and for builders, provides a marketing edge. The main reason is market differentiation; the ability to offer a house with substantially reduced energy bills is a distinct advantage with new-home buyers.

Some production house builders choose to build every house in their community to near-ZEH standards. Other builders pre-plot a selection of residences in their communities to be near-ZEH and offer it as an option, as well. Still others build a near-ZEH model to offer the features as an option, much like granite countertops or a fifth bedroom.

Each of the 257 single-family and town homes at Clarum Homes’ Vista Montaña community generates electricity with a 1.2- to 2.4-kilowatt photovoltaic system. Shown is the model complex at Vista Montaña.
Photo: John Suppes, Clarum Homes

In August 2003, Clarum Homes opened the doors at Vista Montaña, California’s largest near-ZEH community. Each of the 257 single-family and town houses generate electricity with a 1.2- to 2.4-kilowatt (kW) PV system. Clarum, a small builder in Northern California, chose against advertising the near-ZEH community, instead relying solely on the numerous media stories generated by its press event. Many people toured Clarum’s enviro-studio — a converted garage in one of the models demonstrating the energy-efficient features of the house. Vista Montaña was so well received that Clarum has decided to build only near-ZEH in the future.

Pardee Homes, a large regional builder in California and Nevada, started by offering a single model with near-ZEH features as an option. Last summer in San Diego, Pardee opened the Soleil at Bordeaux community, where 10 percent of the houses are ZEHs, another 20 percent come standard with PV systems, and 98 percent of the lots are “ZEH possibilities.” This year, Pardee will open another seven communities in California using a similar strategy.

For production builders, the ability to offer a house with substantially reduced energy bills is a distinct market advantage.

Premier Homes, working with the Sacramento Municipal Utility District (SMUD), opened the first near-zero-energy community in Sacramento, California, in April 2004. Designed to save homebuyers up to 60 percent on utility costs, each of the 95 houses in this community included a package of super energy-efficiency and 2.4-kW PV electricity-generating system. Like Clarum’s Vista Montaña, Premier Gardens offered near-ZEH to entry-level buyers as part of the standard package. In doing so, Premier sought to differentiate its product from other houses, promote innovative construction and energy efficiency and benefit the community. The result was fast sales, high visibility and much good will from local citizens. The community was so successful that a second “Premier ProEnergy Community” is under way in nearby Roseville in conjunction with Roseville Electric, the local utility provider.

Some builders come to near-ZEH projects in atypical ways, as in the case of Morrison Homes. The builder’s initial reason for considering near-ZEH at Morrison Homes at Lakeside was to help generate traffic at an “in-fill” project, an area where houses would be built on vacant parcels of land in developed areas. Ten percent of houses at this master-planned community in a suburb of Sacramento were built to near-ZEH standards. With the help of SMUD, which provided solar buy-downs, efficiency rebates and marketing support, and ConSol providing energy design expertise, the project attracted great buyer interest.

Getting to Widespread Adoption
As with many emerging technologies, the high cost of near-ZEH adoption is a challenge for builders and consumers. Without utility or state buy-downs, a 2.4-kW PV system can add about $18,000 to the cost of the average production home. Utility programs that subsidize or “buy down” installation of solar PV systems cut the net costs substantially — often by as much as half. The goal of these programs is to increase production, which produces economies of scale and reduces product costs. Builders, architects and house designers have not been quick to jump on the near-ZEH bandwagon for other reasons as well: fear of new building methods and concerns about equipment maintenance, warranties, potential litigation and long-term product reliability. Objections about appearance, roof pitch, roofline and the limited choice of PV colors impede their efforts, too.

Zero-Energy Home Debuts on “Extreme Makeover”

Energy-efficiency experts volunteer expertise on reality TV series.

A blended family in need was the inspiration for more than 800 volunteers, led by builder Pardee Homes, who came together in February to construct a home in four days for the ABC-TV show, “Extreme Makeover: Home Edition.” ConSol designed the house to exceed the requirements of the new California Energy Commission Zero-Energy New Homes program (ZENH).

This was no ordinary house. To house the family’s three adults and eight children, it morphed from a 1,200-square-foot tract house to a custom-built, 4,200-square-foot, nine-bedroom super-energy-efficient house, complete with pond, waterfall and Jacuzzi in the backyard. The house sports a 3.0-kilowatt (kW) roof-integrated photovoltaic system. The house also is the first that exceeds all ZENH requirements, according to ConSol. ZENH requires homes to save 70 percent in annual electricity bills, and not draw more than 1 kW of electricity during peak usage times.

Rob Hammon and energy-efficiency consulting firm ConSol played a key role: donating the energy-efficient-design services, and helping to ensure that the energy-efficiency and thermal comfort features were installed properly. When the ConSol crew arrived on site, the project was already behind schedule. They donned gold hard hats to help other subcontractors catch up, snagging one-hour naps in the rental cars when they could, and waiting to do their part, all in a 36-hour shift.

The show aired March 27 and 28.

Rob Hammon (foreground) explains energy-efficiency building methods to the production crew, while framers and roofers race to complete the house on schedule.
Photo: ConSol

Builders are finding, however, that those who build more fiscally and environmentally sensible houses earn the respect, trust and thanks of the community and local government. The greatest benefit of the near-ZEH concept for a buyer is the most obvious — dramatically reduced electricity bills over the life of the house. Depending on energy usage, family size and square footage of the house, the near-ZEH owner can conservatively expect to save about $1,200 per year at California’s utility prices. This payback on a near-ZEH is relatively long, but it can provide positive cash flow immediately. Near-ZEH owners also are largely immune to utility rate hikes.

No matter how great the benefits, many builders will delay in adopting new features and practices until they have been well proven by others — or until forced to do so. Proponents hope that the successes in California can demonstrate that with the right market conditions, near-ZEH neighborhoods are a good investment for builders and their buyers. New, improved and reliable technologies, coupled with continued public and private investments in PV, will produce more near-ZEH communities. As support from production house builders and demand from homebuyers grow, it is not a matter of if these communities will proliferate, but when.

A recent survey conducted by the Davis Energy Group found that 67 percent of recent homebuyers likely would have paid $8,000 more for their new house if it generated 40 percent of its own electricity. Another 26 percent said they would have considered it. Most consumers embrace the idea of harnessing the sun for renewable, reliable energy. But most consumers are unaware that the Zero Energy Home program even exists. The DOE’s Building America program has a budget for R&D, but not for marketing and outreach efforts. We, as an industry, need to do a better job of educating consumers and suppliers that we have the means to produce reliable power for an entire house while minimizing harmful greenhouse gases and dependence on foreign, volatile sources of raw materials.

Homes that combine solar energy systems with energy-efficient technologies in a few California communities have proven to be affordable for builders and competitive in the market. But the elements that have made near-ZEH a success here are not unique to California. Those of us working to promote national near-ZEH adoption look forward to seeing builders in other regions expand on what we have done. Continued cooperation in the building community and continued development of community- and utility-based programs can result not only in widespread adoption in California, but in the fruition of DOE’s long-term goal for near-ZEH to become mainstream across the United States.

As builders and consumers come to appreciate the benefits of ZEH, the obstacles will be overcome. As 18th century statesman Edmund Burke put it, “Nobody made a greater mistake than he who did nothing because he could only do a little.” A handful of production builders are doing more than a little.

Rob Hammon, Ph.D., is principal of ConSol, an energy-consulting firm in Stockton, Calif., that has over 18 years’ experience in energy consulting, energy-efficient building design and energy regulations. Hammon specializes in market analysis, energy-savings assessments, interpretation of regulations and training of the building industry. Contact Hammon at rob@consol.ws or access ConSol at www.consol.ws.

By Rob Hammon