ForJohn Kosmer, home improvement editor ofVictorian Homesmagazine for 23 years, the decision to look at solar energy concepts when planning the design of his new home was based on both financial and personal factors.
“We bought land with a southern panoramic view that I knew we would like to see,” Kosmer recalls. “South-facing windows are essential for passive solar.
“In addition, we wanted to position ourselves for retirement when we knew that, statistically, our incomes would decline. Solar seemed like a good hedge against that possibility and rising fuel costs,” he says, adding, “We were ahead of the curve by about two years. By June 1, 2007, when we moved into the house, crude was in the $60-a-barrel range.”
As Kosmer and the rest of America found out shortly after, crude prices were about to spike to the current $100+ per barrel, justifying Kosmer’s prediction.
Kosmer says he started out on the margins of energy conservation by trying to save energy in his existing home. But when he bought property in Fly Creek, N.Y., he decided to consult a contractor,John Carrigan, principle of Building with Integrity (www.Building-With-Integrity.com) in upstate New York, who was interested in a whole-house solar energy system concept. “We chose our contractor because of his excellent history and because he was young and saw the future in front of him, so he was open to learning new things,” Kosmer notes.
Carrigan received special training fromBruce Brownell, principle and founder of Adirondak Alternate Energy (www.aaepassivesolar.com) and a nationally recognized solar engineer, on the specific construction methods used to build this house. Brownell has been building and improving passive solar energy systems in more than 300 homes for the past 30 years. This was Carrigan’s first solar house and he relied on Brownell and the experts from Baxi Boiler for the combination propane/hot water solar panel heat for domestic hot water and closed-loop hot water for auxiliary heat.
Kosmer says the home was built for $125 a square foot, about the same as a comparably sized Energy Star-qualified home, but uses 70 percent less energy to heat. He notes that 80-percent savings would be possible if the home was not in the snow belt of New York and had regular height ceilings. The 4,000-square-foot home is estimated to have heating costs in the $900 to $1,200 range per year (assuming crude oil is $100 a barrel) in the cold climate of upstate New York. “My propane costs from June 1, 2007, to March 26, 2008, are about $800,” he adds. “If the house was in the 2,000- to 2,500-square-foot range, the savings would be even more dramatic.”
Saving 70-80 percent on his heating bills adds up to serious money, Kosmer says, especially when you figure in an $80 monthly electric bill, due to having more natural light more of the time, energy-efficient appliances, compact fluorescent bulbs and LED bulbs. The energy savings are staggering, he says.
“It became clear to me that existing 20th century homes are obsolete energy sieves that will take Herculean measures to bring up-to-speed in the 21st century,” he says, “and any new home design that did not achieve similar savings would be a nonstarter in this new epoch.”
To share this information on the benefits of solar energy, Kosmer decided to launch a Web site atwww.solarhomeproject.comproviding details on his home’s construction and its energy-conserving system, including in-depth descriptions of how the solar concepts work. “Only a singular comprehensive statement, like a Web site, could begin to clearly articulate how the home was built and how it functions as a system,” Kosmer says. “This information had to be contextualized in an era of rising energy costs and obsolete building notions. It needs to be available to the public so we can rebuild America one house at a time.”
Solar House DesignKosmer attributes the low cost of heating this mainstream, traditional-style home to the sun. The house retains the heat from the sun by being totally encased in a super energy-efficient shell of 4-inch thick rigid polyurethane insulation, not only on the exterior walls, but also beneath the 12-inch concrete slab and on the roof. “Using rigid insulation around the entire house is like building a soda picnic cooler, except you’re the soda,” Kosmer says on his Web site.
Simonton ProFinish Energy Star-qualified low E double-glazed windows and their correct placement for maximum solar gain and minimum heat loss, along with 4 inches of the rigid insulation, combine to form the thermal envelope to retain heat in the winter and resist heat in the summer.
In addition, a state-of-the-art Energy Star-qualified Baxi Luna 3 boiler and Baxi solar hot water panels provide supplementary heat during the coldest periods. Kosmer says that the Baxi boiler would work well enough on its own, but combined with Baxi solar hot water panels, “the results are spectacular.”
When the Baxi boiler senses stored preheated hot water in the holding tank produced by the Baxi solar hot water panels, it takes less energy to bring that water up to temperature for domestic hot water and closed-loop hot water for auxiliary heat. When the water in the holding tank is already hot enough, the Baxi senses it and simply acts as a pass-though for that hot water without turning on at all.
Kosmer says that, thanks to the efficient heat-retaining structure, everything helps to heat the home - not just the sun and the supplementary heating plant. Lighting (regular and energy-efficient bulbs), appliances and even body heat contribute to the heat gain of the home. There is also a state-of-the-art wood stove to provide backup heat when necessary. Less electricity is also required due to the abundance of natural light.
Unlike earlier passive solar homes noted for their uneven heat absorption and distribution cycle, Kosmer says, this passive solar home uses a ducted air heat transfer system. Air ducts run through the 1-foot thick thermal mass concrete slab throughout the home and constantly circulate the air.
Instead of solely relying on the sun to warm the surface of the thermal mass concrete slab (usually uneven, mostly on the side of the floor facing south where there are windows), the ducts take the heated air in the house warmed by the sun and store it evenly throughout the body of the slab. A large squirrel-cage fan draws the air down a vertical shaft from the air return grilles in the attic and then pushes the air into the main trunk duct and its tributary ducts dispersed within the slab.
From the slab, the air travels back into the house, up air ducts that open on every floor. This duct system allows the thermal slab to act as a more efficient thermal storage battery, storing more heat and storing it more quickly and evenly than a passive solar home without ducts, Kosmer notes. In the cooler evening hours, while the concrete slab is releasing heat from its surface, those ducts draw heat from within the slab and evenly deliver heated air to the whole house.
Passive solar homes operate on the simple physics principal that everything wants to even out to the same temperature, Kosmer says. “Pour hot coffee into a cold mug and within minutes the mug heats up and the coffee cools down until they are both the same temperature,” he says. “That principle describes how the 1-foot thick thermal mass concrete slab solar storage battery works.”
During the day, when this slab is colder than the house, the slab absorbs heat, mostly generated by the sun warming the air in the house. In the evening, when the slab becomes warmer than the house, the slab releases the heat. Brownell’s ducted air heat transfer system and thermal shell design optimizes the efficiency of this heat transfer and dramatically minimizes heat loss, Kosmer reports.
The Definition Of GreenBuilding “green” and embracing sustainability encompasses many areas besides energy efficiency, Kosmer’s Web site notes. One measure is creating a small footprint to impact the environment less and to minimize building materials. This passive solar home is only about 30 feet by 50 feet, with an attached 30-foot by 34-foot garage. It achieves its total square footage by having an attic that is usable heated space.
A solar house, by its nature, should be a simpler architectural form (like a long rectangle) to maximize solar gain, Kosmer says. These simpler architectural building forms minimize building materials and building costs without sacrificing distinctive design.
“Green” also means using recycled and renewable resource materials, Kosmer notes. He points out on his Web site that the ceramic tiles used in the bathrooms and for the backsplash in the kitchen are Crossville Ceramic Eco-tiles made with SCS-certified recycled content. In addition, the bamboo in the Mannington flooring is a renewable resource.
To address another meaning of “green” (i.e., product life cycle), the home’s Certainteed Presidential Shake asphalt roofing and the James Hardie HardiePlank concrete siding and trim all have a 50-year limited warranty, and there is a 15-year limited warranty on the pre-finished color coating.
Additional green elements in the home include:
- GE Energy Star-qualified Profile appliances.
- Therma-Tru Energy Star-qualified exterior doors.
- Velux Energy Star-qualified skylights.
- Dow Tuff-R Rigid insulation on the exterior surfaces and Certainteed fiberglass insulation in the interior cavities.
- Vermont Castings Defiant high-efficiency noncatalytic converter wood stove.
- Pinnacle Supply’s high-tech insulated double-line water Time Saver pipe.
a very important role in a passive solar house, Kosmer notes. To facilitate
maximum solar gain, the Kosmer solar house had to be oriented so its long side,
the side with most of the home’s windows, faced due south. South-facing windows
are net gainers, absorbing more energy during the day due to their direct
exposure to the sun than they will release at night.
The south windows also act as a switch to turn on and off maximum solar gain, Kosmer says. In the winter, the sun is low and shines directly through the glass, providing maximum solar gain. In the spring, the sun’s height increases and reaches a high enough angle on the glass that much of the sun’s energy is refracted off the glass back outside, limiting solar gain. In the fall, the sun’s angle falls again, turning on maximum solar gain by directly passing through the glass again.
Role Of The Attic
According to Kosmer, another advantage of having rigid
insulation on the outside of the house (including the roof) is that, even
though the attic is unfinished, it is inside the thermal envelope of the house
and is therefore heated usable space.
To maximize the attic space, he built 2-foot-high knee walls that gave the attic ceiling more height. The only air return for the house is in the attic. Warm air naturally rises up to the attic, where it is drawn into grilles in a horizontal shaft at the peak of the attic ceiling. There it begins its rotation down the vertical shaft through the squirrel-cage fan and then into the slab and back up throughout the house. The attic, first and second floors are always within 3 degrees of each other because they are all in the thermal envelope.
The Kosmer home has an attached three-car garage that is insulated the same way as the house. The only difference is that it has no ductwork and has only a 6-inch slab. The windows still face south for solar gain. In the attic ceiling, they used a modified truss so they were able to have a 6.5-foot high by 11-foot wide by 30-foot long storage space above the garage. The temperature in the passive solar garage won’t fall below freezing, even in severe weather.
Heat in a traditional home dries out the air as the winter progresses, sometimes reaching as low as 20-percent humidity. In the Kosmer passive solar home, the humidity is always about 40 to 50 percent, Kosmer reports. One of the most difficult aspects of the passive solar air handling system to explain, he says, is how good the fresh the air feels because it passes through the HEPA-like filters. “People who visit say it feels like a clear spring day,” he says.
Promoting Solar For EveryoneWhen asked about his plans for promoting solar concepts in the future, Kosmer assures, “I am carefully monitoring the ongoing developments in photovoltaics, wind, solar air transfer, ground source heat pumps and all other components that may increase home energy efficiency.”
He notes that there are opportunities for including solar designs in the market that exist now. “There are two major home challenges in our present collapsed building market for the foreseeable future,” he says. “One challenge is to provide a blueprint that enables all new-home construction to achieve energy savings similar to my passive solar home.
“The other challenge is to develop strategies that improve the energy efficiency of existing homes so they remain desirable to live in and competitive to the new super-efficient homes as energy costs continue to rise. Unfortunately, that challenge has not yet been met.”
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