DOE concurs, noting that masonry heaters “produce more heat and less pollution than any other wood- or pellet-burning appliance.” A small, hot fire, built once or twice a day, releases heated gases into the long masonry heat tunnels, where the heat is absorbed and then slowly released into the house over a period of 12 to 20 hours.
Unfortunately, masonry heaters—whether custom-built or prefabricated by manufacturers such as Tulikivi Corp.—are pricey. They also can't generate quick heat from a cold start. What's more, some jurisdictions have “no-burn” days that restrict the operation of fire-burning products, thus requiring homeowners to have a back-up heating system. And although other fire-based renewable heating alternatives are relatively inexpensive and efficient—and often burn recycled materials such as wood waste, wheat, and corn—many architects see them as supplementary sources or better suited to a vacation home.exchange rate
Perhaps the most efficient heating system available today is geothermal exchange—a process powered by the earth's natural heat. According to the Washington, D.C.-based Geothermal Heat Pump Consortium (GHPC), the system works “by attaching geothermal heat pumps to the ground through either a series of buried plastic pipes (closed loop) or water wells (open loop), often beneath parking lots or green areas.” Because the earth's soil temperature at depths of 6 feet or greater consistently ranges from 45 degrees to 70 degrees, it's an ideal source for heating and cooling. Proponents insist geothermal requires less energy and has much lower operating costs than traditional systems. In fact, GHPC says the typical 2,000-square-foot home can be heated and cooled for as little as $1 a day.
Steve Brown, owner of Carl Franklin Homes in Dallas, has been using geothermal in his homes since 1993. He's convinced the technology has no equal. “The principle behind the system makes a lot of sense,” he says. “The entire unit sits in the conditioned attic space, so it's functioning where it's operating and the pump is pulling no energy.” Vigil is equally enamored of the technology. “My fantasy system would be a photovoltaic system on the roof that runs a geothermal system,” he says. Still, Brown acknowledges that geothermal systems aren't suitable for every home. They're more effective in moderately cold climates, for instance, but less so in areas with severe winters. Additionally, the technology is overkill for houses, especially tightly constructed ones, that are smaller than 1,400 square feet. For houses measuring more than 2,000 square feet, “geothermal will work great,” he adds.
Credit: California Energy Commission
Geothermal technology uses the earth's consistent ground temperature to condition a space. Although pricey, it's considered the most efficient system available.
Proper installation is also vitally important, warns Paul E. Duncker, AIA, principal of HandsOn Design. For his home in Wilson, Wyo., the architect used an unconventional method instead of the typical trenches. The result was a system that hasn't been as effective as it could have been. He's had better luck since then, however. For some recent clients, “I went by the book,” he says, “digging long trenches and using a consultant ... to do the heat-loss calculations and soils investigation. This time, the heat pump and ground loop are sized correctly, and the unit has been delivering significant savings to the owners.”
A geothermal system will save money in the long run, but the up-front costs are significant. In addition to the heat pump, which can run around $13,000, there are well-digging costs to consider. There's no way for a single home to avoid this expense, of course, but developers are finding ways to mitigate it. “In Dallas,” Brown says, “we're starting to see developers put in loop lines and spider systems that allow multiple homes to feed off one system,” thus reducing the overall cost.
Although every alternative heating system has its benefits, there's no single application that works for everyone. Analyzing your client's budget, home size, and heating needs will help you determine the best application. As a matter of course, Vigil says all architects should site their houses to receive free heat from the sun and construct a super-tight building envelope. From there, the sky (and the ground) are the limit.