Cave-dwellers — human and otherwise — have figured it out for millennia: Winters are warmer when you’re fur-lined, in a burrow.
Varieties of geothermal heat that boast substantially better ventilation, lighting and comfort will be discussed at a forum at 1 p.m. Saturday, April 17 at Burlington’s Contois Auditorium.
The variety will hew to a remarkable constant: In Vermont, Mother Earth’s bosom remains at a steady 50-or-so-degrees, winter and summer.
Skeptical? Consider: Well water, refreshingly cool in the summer, feels warm in January. Similarly, water bumped up by 20 or 30 degrees in a heat pump can circulate through floor piping or be used to warm circulating air.
Advances in energy-transfer technologies have brought these systems within tantalizing reach of more and more homeowners and businesses, said Sen. Bernie Sanders, who is playing host to next week’s forum.
“Geothermal energy has a very significant potential here in Vermont and in the rest of the country,” the Vermont independent said. “We need to discuss its potential here, where it works and where it doesn’t work.”
Sanders said he will defer to a panel of experts — including Assistant U.S. Secretary for Energy Efficiency and Renewable Energy Cathy Zoi — to plumb the details. But, he noted, the latest round of federal alternative-energy stimulus funding includes provisions for geothermal.
Is geothermal for everyone? Absolutely not, the experts tell us.
Bells and whistles
But does it work?
Absolutely, said panelist and architect David Pill of Charlotte.
He and his wife, Hillary Maharam, live in a wind-powered, solar- and geothermal-heated house they completed in August 2007.
As with many new houses, it began with a well.
“We needed one anyway, for our domestic water,” Pill said.
Would it be enough for a geothermal system? “It’s always a gamble,” Pill said.
He hired a douser, and then a well-driller. With other specialists, notably Andy Shapiro of Energy Balance, Inc., he matched the well’s flow to floor space and heat pump size.
It worked. The water-warmed ground-floor slab evenly heats the entire two-story, 2,700-square-foot house.
Last year Pill’s house won a $10,000 prize from Northeast Sustainable Energy Association for its imaginative and effective design — and its performance (it generated more power than it consumed, including cooking and hot water, making it a “net-zero” structure).
In February, his house was one of four buildings cited for excellence by the Sustainable Building Industry Council (the Empire State Building won top honors for the successful retrofit of its energy management systems).
For newcomers to the field, Pill has two bits of key advice. They have nothing to do with wells and heat pumps:
• Be sure your building’s orientation takes advantage of passive solar radiation.
• Super-insulate your building’s envelope.
“You want to start with the lowest possible energy budget. Then you can think about adding on all the bells and whistles,” Pill said. “You want to first get your house to a point that it doesn’t take much more to heat it.”
Tailoring a renewable energy system to a “renewable-ready” house will cut back on steep start-up costs, he added; the rule of thumb for payback on a well-engineered geothermal systems is 8 – 10 years.
But, Pill pointed out, he pays nothing for fuel, and actually sells his excess electricity back to the utility.
His last bit of advice has everything to do with wells and heat pumps. It’s a pet peeve: “Instead of ‘geothermal,’ I wish people would call these ‘ground-source heat-pump’ systems, or GSHP’” he said. “¤‘Geothermal’ makes it sound like a hot spring.”
Without fanfare, a growing number of Vermont homes and businesses are turning to GSHP systems. Creators of some of them plan to attend next week’s forum.
In the past two years, developer Chuck Reiss built four solar/geothermal homes in Hinesburg’s South Farm neighborhood, and one apiece in Wayland, Brandon and Waterbury. All of them, like Pill’s, radiate heat through a concrete slab; all of them efficiently hold heat; all of them generate more than enough electricity to operate.
Jeff Williams, vice president of Jericho-based Spafford and Sons Water Wells, designed his 36-by-48-foot maintenance barn around a well he drilled. The heat pump he installed is about the size of an automatic dishwasher — and at full throttle, runs about as loud.
Williams estimates the initial outlay for geothermal at roughly twice that of fossil-fuel-powered heating and cooling systems. But if the customer already owns a reasonably deep well, the price point plummets. He expects to break even on his $12,000 investment in seven to 10 years, and enjoy another 20 years of half-price heat with few if any maintenance costs.
A home on Van Sicklen Road in South Burlington, designed by Warren-based architect John Connell, boasts a gusher of a well: it’s been rated at 70 gallons per minute. That’s enough to heat several houses, said the project’s geothermal consultant, Harold Rist, president of Queensbury, N.Y. -based Smart-Energy.
Rist’s Web site (www.smart-nrg.com) is packed with information for newcomers to the field as well as experts who might want to weigh in on controversies. Rist cautions that radiating slabs might be far less efficient than systems that warm circulating air: “The laws of physics will catch up with you eventually.”
He inveighs against “closed-loop” systems — those that circulate synthetic heat-transfer fluids through wells or underground pipe networks — because they neglect long-term environmental consequences.
“There’s an awful lot of greed in the geothermal energy business, and no one will be the wiser until the next earthquake,” he said.
Last year, well-drillers in Burlington’s Hill District assembled equipment to sink three vertical shafts, each of them extending down 2,000 feet. The goal: to harvest enough energy from rock-heated water to heat — and cool — a new 22,300 square-foot Champlain College visitors’ center built around renovated Perry Hall.
As with Pill’s project, the developers gambled and won. They needed only two wells, the deepest descending no more than 800 feet.
Most of the system has been installed.
Pipes and ducts run alongside the 1859 stone foundations, into the newer wings and through 37 heat pumps.
College officials say the project will pay for itself within a decade.
Walking through the project recently, Michel George, associate vice president of campus planning and auxiliary services, said Perry Hall will demonstrate much more than geological utility when its system fires up later this year.
“It will make a statement where’ve been and where we’re going,” he said.