Investment propertyZero Energy Homes Reach Limited Mass Production
In 1998 a home builder, some photovoltaic (PV) and solar system engineers, renewable energy scientists, university researchers, the city of Lakeland, FL and the State of Florida constructed two homes in a Lakeland suburb.
The 2,425 square foot homes had identical compass orientations and floor plans. One was a conventional home, the other was what"s called a Zero Energy Home (ZEH) -- engineered to reduce the home"s energy loads to as near zero as possible with most of the cooling, water heating, and other daytime electrical needs met by solar energy systems.
The energy use of both homes was monitored for more than a year.
The findings?
"Based on a side-by-side evaluation, energy efficient housing incorporating utility integrated PV power can reduce total electrical consumption by 70 percent or more over traditional housing," according to a detailed analysis of the field test, "Field Evaluation of Efficient Building Technology with Photovoltaic Power Production in New Florida Residential Housing," written by the Florida Solar Energy Center at the University of Central Florida.
Within a few years, a Northern California home builder was mass producing ZEHs.
"We are the only builder in the nation doing 100 percent Zero Energy Homes with standard equipment. Power from the sun is non-polluting, it"s free and there are incentives to homeowners who get rebates for installing systems," said Nicole Gittleson, vice president of marketing at Clarum Homes, a Palo Alto, CA developer that has constructed ZEHs in the California cities of East Palo Alto, Watsonville, and Menlo Park -- for starters.
"The electric meters spin backwards," said Gittleson.
There is a small cost for the safety and security that comes with the legal requirement for each home to be tied to the local power grid, but in many cases ZEHs produce all the energy they need -- with stored power, even in a blackout.
ZEH"s are a first big step toward reducing reliance upon fuels and energy imported, often from unstable regions. The new ZEHs use free and clean renewable energy sources that reduce pollution and help sustain a healthy environment.
What"s most remarkable is that most of the ZEHs under construction are priced competitively with conventional homes.
Rob Hammon, chief consultant on ZEHs for ConSol, a Stockton, CA-based energy consulting firm, says builders are remiss about going zero-energy because of the up-front retooling and training costs which can add $8,000 to $16,000 to the cost of building the home. Once builders are set up to construct the homes, however, mass production helps stabilize cost.
"In the Clarum case, their homes are competitive with other builders down the street," said Hammon.
Over the long haul, the homes actually can be cheaper.
"The increased cost of the home is cut down by the energy cost savings. It"s unlikely they are selling energy back to the utility, but it"s possible to get right to the break-even point. You eventually recoup (any extra cost added to the new home) and it takes a while to do that, but the good news is from the first day, you don"t have much of an electric bill other than a service fee," said Hammon.
Another cost benefit is available in the form of Energy Efficient Mortgages (EEMs) which allow home buyers to qualify for a mortgage that a buyer may not have been otherwise able to afford. The idea is that less money spent on energy can be spent on the home. Likewise, EEMs can let buyers qualify for a larger mortgage and the loans come with Fannie Mae, Freddie Mac and U.S. Housing and Urban Affairs Department (HUD) guidelines.
Other studies show energy-efficient homes can be more valuable on the resale market.
ZEH homes employ three basic strategies:
Tight shells. Homes come with extra insulation in the walls, floors and ceilings; windows that block heat gain; no West-facing windows to avoid the most direct sunlight; and reflective, radiant barrier roofing.
"The system reflects heat, keeping attics 20 to 30 degrees cooler. That"s important not just to reduce heat but to reduce the load on the cooling system. The air ducts are typically in the attic," said Hammon.
Energy efficient equipment. Major appliances exceed Energy Star-rated efficiency levels, HVAC (heating, ventilation and air conditioning) systems are the most efficient and "tankless" water heaters heat water only as needed. Conventional water heaters heat water even when it"s not used.
A cost- and pollution-free energy source. Wind power, fuel cells and biomass generators are alternatives, but all ZEH homes produced thus far use the latest photovoltaic systems to generate energy from the sun.
The U.S. Department of Energy"s (DOE) National Renewable Energy Laboratory administers the largest ZEH pilot program with four teams in the field building ZEHs.
Clarum is part of the ConSol Team, which also includes Morrison Homes, Shea Homes and Pardee Homes, developers building in California and Nevada.
The Davis, CA-based Davis Energy Group Team includes national home builder Centex Corp. and the Florida Solar Energy Center.
From Upper Marlboro, MD the National Association of Home Builders Research Center Team includes the Norwalk, CT Steven Winter Associates and John Wesley Miller Co. which worked on a Tucson, AZ ZEH project.
Teams include building energy efficiency consultants, specialty material and equipment manufacturers, home builders and related professionals.
"In the long term, fossil fuel energy sources are finite, so we are doing research and development to look into ways to reduce that dependence. We import more than 60 percent of our energy sources and not a lot of it comes from the most stable regions in the world," said Jeannie Leggett Sikora, an NAHB Research Center research engineer.
For more information, visit the DOE"s ZEH program online.