HINESBURG -- Outside, the thermometer read minus 1 degree Fahrenheit on Thursday. Inside David and Carrie Fenn's new home, the temperature was a balmy 30 degrees warmer, although the house is unfinished, uninsulated and lacking two doors to shut out the wind.

The Fenns can't wait to move in.

Big, south-facing, heat-capturing windows are the least of what they look forward to in a house designed to use less energy, make its own electricity and draw its heat from the earth.

"We are both very concerned about climate change and sustainability," said David Fenn, a 73-year-old retired computer executive. "We want to do what we can and a very energy-efficient house is one thing we can do."

Welcome to the cutting edge of home building.

South Farm, a six-home development on the edge of Hinesburg village, is one of the first -- if not the first -- Vermont subdivision to aim for "net-zero" status, meaning over the course of a year it will generate more electricity from clean, renewable sources than it draws from utility power lines. Succeeding also means close to zero emissions of carbon dioxide, a greenhouse gas.

Individual Vermonters have been building energy-miser, rustic, off-the-grid homes since the back-to-the-land movement of the late 1960s.

It has taken high oil prices, improved renewable energy technology and the looming threat of global warming to introduce "green" building to the suburbs and the market for $400,000-plus houses.

Already the roof of the Fenns' house is plastered with photovoltaic film to turn sunlight into electricity. Pipes snake down a deep well beside the house, ready to warm the house with geothermal heat. Inside, walls more than 9 inches thick await a stuffing of insulation.

South Farm developer Chuck Reiss is testing the strength and consistency of the wind higher on the hillside. If a 10-kilowatt wind turbine proves feasible, all six homes should achieve energy self-sufficiency.

Their only contribution of greenhouse gases would come from the small amount of propane burned in the homes' cookstoves and clothes dryers.

Jo White has a strategy even for that fossil fuel.

"I love hanging my wash outside to dry," said the 70-year-old retired banker, who hopes to move to her new South Farms home in March.

Saving money,
saving the planet

Vermont lawmakers just wrapped up three weeks of special hearings on global climate change and ways in which the state can reduce its emissions of fossil fuels.

They heard one message repeatedly: One of Vermont's most obvious opportunities to reduce greenhouse gas emissions is making the state's homes and businesses more energy-efficient.

Commercial and residential buildings use almost 40 percent of the energy and 70 percent of the electricity in the United States, according to the federal government. In Vermont, it's estimated that nearly one-third of carbon emissions can be attributed to residential and commercial buildings.

Not to mention the hit that homeowners' wallets take, paying the electric and heating bill -- home heating bills in Vermont can top $1,000 a year.

"I'm 70 years old, on a fixed income. If I want to travel, to do the things I like, then I do have to worry about how I'm spending my money," White said.

Lawmakers are certain to consider extending the state's energy-efficiency programs, which until now have focused on reducing use of electricity. That program could be expanded to help middle-income homeowners improve insulation and stop air leaks in their homes to reduce the amount of heating fuel they burn.

Moving to 'Energy Star'

Meanwhile, the world of new residential construction already has changed.

Vermont has enacted minimum energy standards for all new houses.

Efficiency Vermont, the state-funded efficiency utility, provides technical assistance and some financial incentives for builders to beat the minimum standards by constructing Energy Star homes.

Better insulated, equipped with the most efficient furnaces and energy-efficient appliances and lighting, an Energy Star home will use about 30 percent less energy than a standard home, according to Pat Haller, residential new construction market manager at Efficiency Vermont.

In 2005, 25 percent of new residential units met Energy Star standards in Vermont, Haller said.

Builders tell him qualifying for an Energy Star rating adds about $2,000 to the cost of building a home, he said.

"To get to net-zero, you are going to have to be 50 to 70 percent more efficient than Energy Star. That's hard to do," he said.

Designing for net-zero

Nevertheless, a few home builders are ready to try -- not just a home here and there but whole small subdivisions.

Reiss' South Farm appears to be the first, but builder Tom Moore of Underhill is close behind, with an eight-home subdivision, Locust Knoll, scheduled to break ground this spring off U.S. 2 south of Richmond village.

Both developers are selling not just energy efficiency but the idea of a "green community" of homes built from sustainable materials, near an existing village and beside an organic farm.

South Farm will have a pedestrian path to connect it to Hinesburg village. Residents will be able to walk to the grocery store half a mile away.

In both cases, building near-net-zero homes begins with location. David and Carrie Fenn's home, like all those in the development, is snugged into a south-facing slope to capture the sun and uses the earth as insulation against the back wall of the first floor.

"That sounds easy, but it is hard to orient houses for southern exposure because we all like to have our front door facing the street," Haller said.

Another key is building smaller-than-usual homes -- less than 2,000 square feet at South Farm. The less space to heat and light, the less energy is needed. Double walls and extra insulation also reduce the energy demand of the homes.

"Some builders want to build a net-zero home, but they don't necessarily push themselves to get there. Chuck is really pushing himself," Haller said.

Reiss's combination of solar roofs and geothermal heat, for example, provides the South Farm homes with a zero-carbon source of home heating.

Pipes draw water from deep in the ground through a heat pump that extracts and concentrates the warmth to heat the house. The heat pump uses a lot of electricity, but much of the time that power will come from the solar panels on the roof.

In all, Reiss estimates his homes will use about 5,500 kilowatt-hours of electricity annually to turn on the lights, run most appliances and operate the geothermal heat pump. (The average Green Mountain Power residential customer uses 7,827 kilowatt-hours a year). The solar roof will generate about 4,000 kilowatts. (When the roof is generating more electricity than the home can use, the extra power will flow to the local utility, Green Mountain Power, and the home's electric meter will run backward.)

Until and unless Reiss can install a wind turbine, the homes will draw electricity from Green Mountain Power when their solar roofs are not making power.

Paying a premium

Buying a near-net-zero home is not for everyone. Reiss's homes are likely out of reach for most first-time homebuyers.

"There's no getting around the fact that doing a green building just plain costs more. It costs more to put up a photovoltaic array than not to put it up," said Keith Dewey, the Londonderry architect who is designing Moore's Richmond development.

For this reason, Reiss's buyers (three of the six homes are sold) are older people with homes they can sell to finance the move to South Farm.

White and the Fenns describe themselves as environmentalists willing to pay a premium for a near-net-zero home. Carrie Fenn and Jo White serve together on the Hinesburg Planning Commission, which they would like to see make Energy Star construction a requirement of new homes in town.

Just how close their homes will get to using little or no electricity from the grid will be up to them in part.

"There will be some lifestyle changes for some people," Reiss said. "If you leave the lights on all the time or turn on the dishwasher every five minutes, you will use more electricity."

White said she doesn't see attention to her electric use as a burden.

"I'm a switcher-off of lights. I don't let my car run when I'm not in it. I've always tried to be energy-conscious, not just because it costs more to leave the lights on, but because I don't want to waste energy."