Habitat for Humanity Roaring Fork Valley built these three energy efficient homes in Rifle in 2010. The homes at center and on right achieved ENERGY STAR ratings of 39 and 25, meaning they use 61 and 75 percent less energy than a standard home. The home at left achieved a net-zero energy rating because its larger solar electric system is expected to offset the minimal natural gas usage for hot water and speace heating.
New Habitat for Humanity home
in Rifle achieves “net-zero” rating
for energy use
By Suzie Romig
Clean Energy Economy News
Jan. 5, 2011
Living in a home with no net energy consumption might sound like a high-tech dream in western Colorado, but it’s already happening for one family in Rifle.
The latest home built by the nonprofit Habitat for Humanity of the Roaring Fork Valley is predicted to be “net zero” in energy use, meaning the home will produce as much energy as it uses. Organizers say the net zero home may be a first in Garfield County.
“We got to a net zero home by building the home very efficiently with a modest solar footprint,” said Scott Gilbert, president of the local Habitat chapter. “It was really gratifying and exhilarating for our volunteers to hear the house they were working on was going to be net zero. It was a real cause of pride for everybody to know they were working on something so special.”
The net zero home building process is easier to achieve than one might think, said Silt resident Dan Becker, a certified Home Energy Rating System (HERS) rater and Building Performance Institute analyst, who consulted on the Rifle project. It’s as straightforward as closely following the guidelines for ENERGY STAR homes, starting from the design phase, and insuring a continuous thermal barrier, Becker said. Those guidelines can be found at www.EnergyStar.gov.
Above, framing of the net-zero home was thoroughly insulated with foam, including headers, beams and joists.
Below, walls were heavily insulated to keep the home warm in winter and cool in summer.
Below, the Sunsense Solar crew volunteered their labor to install the solar electric system on the Habitat for Humanity home.
“It is a simple program; it doesn’t take a whole lot of extra money,” Becker said. “It’s not a huge time or material cost for contractors as long as they know what has to be done from the beginning.”
A tightly sealed home built with ENERGY STAR windows and doors, upgraded insulation and added exterior foam board in the walls can lead to at least a 20 percent reduction in the size of the heating system, which is less expensive to operate, Becker said. The net zero home in Rifle is so well insulated that air conditioning should not be needed.
“There are no breaks in the thermal envelope, from below grade continuous to the attic,” Becker said, noting that the solar electric system is the “whistles and bells” capping off a well-built ENERGY STAR home.
Habitat for Humanity organizers, volunteers and donors completed three, two-story, approximately 1,200-square-foot homes in Rifle’s Rim Rock neighborhood, following ENERGY STAR standards. The net zero home has the advantage of a larger 6.3-kilowatt solar electric system. The system was made possible by an additional $6,000 gift from EnCana and donated installation by Sunsense Solar in Carbondale.
Some of the key energy efficiency elements of the net zero home include:
- 2-inch rigid foam installed on outside of concrete foundation stem walls
- Half-inch rigid foam layer added to house exterior underneath the siding
- 92 percent efficient gas furnace
- Tankless hot water heater
- Blown-in insulation to bring attic insulation levels to R-49 and wall insulation values to R-26
- Headers for doors and windows insulated with rigid foam between wood
- Air barrier installed on exterior walls behind the shower stall and the stairway to accommodate blown-in insulation
- Caulking added between sheeting in exterior walls
- Thorough attic sealing to exclude outside air
- All insulation includes interior and exterior air barriers
- ENERGY STAR rated appliances and fixtures installed such as ventilation fans, ceiling fans, light fixtures, kitchen appliances, windows and heating equipment
With the efficient home, the excess electricity produced by the flush-mounted solar panels on the roof should offset the natural gas energy used for heating and hot water, making the home net-zero for energy use. The homeowners, a single mom and her two children, will be coached by Sunsense employees so that the home operates efficiently.
With less energy required from industrial power plants, the home also will have a lower impact on air pollution. The ENERGY STAR report on the home predicts the residence will save 3.3 tons of carbon dioxide, 4.2 pounds of sulfur dioxide and 9.1 pounds of nitrogen oxides from being emitted each year.
Gilbert said the project has inspired the local Habitat for Humanity to strive for net zero on all of their upcoming housing projects, including a duplex underway in Silt, as another way to keep the cost of living affordable for families. The family now living in the net zero home is relieved to get out from under very high monthly energy bills at their previous residence in a trailer in Dotsero.
Editor’s Note: If any other Garfield County homeowners also have a net zero home, please contact CLEER. We’d love to share your story too.
In the news
Rifle Citizen Telegram, Dec. 16, 2010
Zero Energy: Solar panels should meet all electricity needs for one Rifle home
By John Gardner