No matter what style of house you design or where it sits, conditioning its interior will consume a sizable portion of your client's maintenance budget. In fact, the Office of Energy Efficiency and Renewable Energy at the U.S. Department of Energy says heating and cooling typically accounts for about 56 percent of overall energy usage, “making it the largest energy expense for most homes.”
The internal comfort of a home is just as important as its architectural design, yet many homeowners are anything but cozy in their castles. Drafts and temperature differentials are common ailments that plague even new homes. Many factors can be blamed for the problem, but the heating system is often the primary cause.in the hot seat
Most American homeowners heat their houses with forced air or a boiler that distributes heat to radiators. Both systems have inefficiencies, however, so industry pros often pursue more comfortable, energy-efficient alternatives. Architect C. Joseph Vigil IV, president of Boulder, Colo.-based VaST, is sold on in-floor hydronic (liquid-based) radiant heat. “I spec it for every house I do,” he says. His preferred installation consists of tubes cast in a 2.5-inch concrete slab; a central boiler that heats the water; and up to seven temperature-control zones, depending on the size of the house.
Heat-retaining masonry fireplaces, such as this Tulikivi unit, burn cleanly and efficiently. Many can warm a reasonably sized house.
Vigil's own home has radiant heat on both levels. He cites several reasons for the choice. “A forced-air [system] has to blow a lot hotter than you imagine to warm a space,” he explains. “That hot air rises and immediately goes to the ceiling and then migrates down to the floor, so it's inefficient.” Radiant, on the other hand, “is much more comfortable, and you can set the temperature lower.”
DOE agrees that radiant is more efficient than baseboard heating and usually more efficient than forced-air heating, because no energy is lost through ducts. “Hydronic systems use little electricity—a benefit for homes off the power grid or in areas with high electricity prices,” it reports.
But radiant heat has its issues. Perhaps its biggest obstacle is initial expense. “A forced-air system in a new home would cost about $15,000, as a rule of thumb,” Vigil says, but radiant “will cost you $30,000. My guess is that the payback is about 10 years.” And because radiant only addresses heating, homeowners in warmer climates must pony up for a separate cooling system as well.
Some green building resources even go so far as to say that radiant systems aren't always necessary, as BuildingGreen.com did in “Radiant-Floor Heating: When It Does—and Doesn't—Make Sense” (2002). Unless a homeowner is using a solar energy source, radiant heat still relies on fossil fuels, thus depleting the environment of its resources. As an alternative, the National Biodiesel Board (NBB) in Jefferson City, Mo., suggests Bioheat, a fuel that combines biodiesel and traditional home heating oil. Jenna Higgins, NBB's director of communications, describes it as “nontoxic, biodegradable, and renewable.”
Promoted mostly as a fuel for diesel-powered vehicles, biodiesel is comprised of 5 percent or 20 percent soybean oil or recycled cooking oil and home heating oil, and according to NBB, is a perfect additive or replacement fuel in a standard oil-fired furnace or boiler. Higgins says biodiesel reduces emissions when burned in home heating oil and costs either the same or slightly more per gallon than regular home heating oil.
But biodiesel has limited applications. The Washington, D.C.-based Energy Information Administration (EIA) reports that, of the 107 million households in the United States, roughly 8.1 million use heating oil as their main heating fuel; 6.3 million of those houses are in the Northeast alone. EIA's “Residential Heating Oil Prices: What Consumers Should Know” (2006) goes on to note that, “In other regions, older homes have been converted from oil heat to gas heat, and oil no longer has a noticeable share of the new-home construction market.”
One ancient alternative with appealing potential is fire—in the form of pellet stoves and other high-efficiency wood heaters. Peter T. Schmelzer, AIA, LEED AP, president of Vivus Architecture + Design, Northfield, Minn., cites masonry heaters as a favorite spec. “A soapstone stove burns very hot and radiates that heat to the entire house,” he explains. Even in cold climates, it can serve “as a primary source of heat.”