WALPOLE – It's one thing to remember to recycle, to use energy efficient light bulbs and forgo plastic at the grocery store. But if homeowners can "teach" their homes to actually give energy back, now you're cooking with gas.

At least one home builder in the state has learned how to do just that and has tested the technology on a home in Unity, Maine.

The architects and builders at Bensonwood Homes in Walpole put their green thumbs to the test when Mitch and Cindy Thomashow had them concoct a sustainable and energy-efficient home.

Unity House, as it's called, recently received an LEED Platinum certification from the U.S. Green Building Council, the highest achievable green building designation. The house also achieved what Bensonwood architect Randall Walter calls a Net Positive effect, which means the house actually gives energy back to the grid. This is done in part with the use of solar panels.

"On a sunny day, the house is building up a credit, to use at night," Walter said.

These credits add up, saving money and energy, Walter said.

The home uses a combination of photovoltaic solar panels for generating electricity and a separate solar hot water system, along with some tight and high-tech insulation.

Cindy and Mitch Thomashow, who is the president of Unity College, which specializes in environmental studies, have opened their home to students interested in learning how to make a home more sustainable and energy efficient.

This Unity, Maine, home was constructed by Bensonwood Homes of Walpole. The home has received LEED Platinum certification from the U.S. Green Building Council and produces more energy than it uses.

"It was not enough for us to live in a so-called 'green' house: we wanted our home to demonstrate to our students and to the world that even in Maine, if it's designed correctly, a home's power usage can balance out or even produce as much energy as it uses," said Mitch Thomashow.

They have described these tutorials on their blog. Cindy Thomashow described one such event.

"Some students dropped to the floor to touch the cement and wonder at its warmth -- assuming that cement will be cold in winter," she wrote. "They shake their heads at the use of Advantech (oriented strand board made from 'junk' wood) as paneling in the living room, which is usually hidden from view in attics or used as sub-flooring. In this house, it is sanded and oiled to look like marbleized wood."

She goes on to describe the home's countertops made of "paper stone" which is constructed from 100 percent post-consumer recycled paper.

"Living in the Green House is all about opening minds to new ways of using materials -- living virtuously and frugally while in great comfort!," she wrote.

The 1,930-square-foot home also has windows that provide passive solar heating, which means even in December, when outside temperatures dropped, the Thomashows, rarely needed to use energy from the home's solar panels for heating.

Further, Unity House was constructed on a concrete slab to retain heat in the winter and help cool the house in the summer and outfitted with high-efficiency appliances and low-flow water fixtures.

Walter pointed out Maine was a good place to test out whether a net positive could be achieved given its low levels of winter sunlight. And despite an especially dreary summer, the house still made enough of its own energy to give some back to the grid.

"So not only is Unity House Net-Zero -- despite what were easily the worst seasonal conditions for the performance of a solar powered, zero energy home -- we believe that in an average year, it will produce quite a bit more energy than it uses," said Tedd Benson founder of Bensonwood Homes. "This is a significant accomplishment when you consider Unity House did not have the benefits of warm weather and high amounts of sunlight that Net-Zero homes built in more temperate or sunnier climates can expect."

The home is connected to a local power grid, which acts as a battery during periods of low sunlight.

From Oct. 5, 2008 to Oct. 5, 2009, energy use data shows Unity House produced 6,441 kilowatt hours of electricity while using only 6,430 kwh. The data shows that the cumulative months of overcast conditions and unseasonably cold temperatures in the first three seasons of 2009, considerably dampened solar collection, yet the home's heat and power production and retention still performed well.

Walter said Bensonwood is working on several more Net Zero homes throughout New England and expects to begin work on a few more next year.