Unity House models sustainability

When Mitch and Cindy Thomashow moved into their new home last year, they knew they were living in one of the most sustainable and energy efficient homes in Maine, and likely the Northeast.Mitch Thomashow, president of Unity College, an environmental college in Unity, Maine, and his wife are both environmental educators so it was important to them that their home reflects their personal and professional ideologies.Known as Unity House, the home uses a mixture of photovoltaic solar panels for generating electricity and a separate solar hot water system, along with an extremely tight, super-insulated building envelope and passive solar design elements. The two hoped the design of the home would help it achieve net-zero status, producing as much energy as 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 than it uses,” said Mitch Thomashow.Designed and built by Bensonwood Homes in Walpole, N.H., Unity House earlier this year received LEED Platinum certification from the U.S. Green Building Council, the highest achievable green building designation. While the home is connected to the local power grid, it is built to be energy independent and is one of only seven certified LEED Platinum residences in New England (BrightBuilt Barn, also built by Bensonwood, is on the list as well.) Indeed, with net-zero documentation now added to its LEED Platinum certification, Unity is among only a handful of such buildings nationwide.Despite the climateFrom 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/retention performed exceptionally well despite those limiting factors.Most important, the home was comfortable throughout the year.“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.”Benson added that the home “also validates the architecture and building methods that went into creating this house and further demonstrates a way to build more sustainable, affordable and adaptable homes.”Unity House has a number of elements added into its design to ensure sustainable living standards.The 1,930-square-foot home is highly insulated, has an extremely tight thermal envelope and its windows provide passive solar heating, which means that, as late as last December, when outside temperatures dropped into the teens, the Thomashows rarely needed to use energy from the home’s photovoltaic solar panels to heat the home. Unity House was constructed on a concrete slab to retain heat in the winter and help cool the house in the summer. High-efficiency appliances and low-flow water fixtures also were added, and with Bensonwood’s Open-Built designs, interior walls can be moved or detached using simple tools, creating new space for its residents.“Unity House clearly shows that even under harsh weather conditions, real homes can be built for real people that are affordable, livable and energy independent,” said Benson. “This isn’t the future of home building: this is how homes can and should be produced right now.”