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Home is where the heat is off

An extremely green house rises in Roxbury

By Carolyn Y. Johnson
Globe Staff / October 25, 2009

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At a time when most people are contemplating whether to give in and turn up the thermostat, Simon Hare and his family are embarking on a bold experiment in green living: a winter with no heat.

Their modest, two-story cottage in Roxbury will be warmed by the sun, the body heat of Hare, his wife Damiana, and his 16-month-old daughter Lulu, and even the heat thrown off by its energy-efficient appliances. The airtight, well-insulated house is part of a small but growing movement to design and build extremely green dwellings by rethinking what is essential in a house.

“You make it really efficient; you design your house to do your work for you,’’ Hare said. “On a February day of 6 degrees, if it’s getting cool, we can heat the house by making a second batch of pancakes for my daughter.’’

As world leaders prepare to negotiate a new climate change agreement in Copenhagen in December, some homeowners are taking matters into their own hands, building structures that show just how far it is possible to shrink a house’s carbon footprint. While many green buildings are built from scratch on lots ideally situated for sunlight, a growing number of builders and designers are, like Hare, working with existing buildings, and studying the best ways to integrate green building techniques to densely populated, built-out urban areas like Boston.

Hare - owner of a small design and build firm called Placetailor - had hoped to save the original building, a gunsmith’s cottage from 1850, but the structure was too damaged. Instead, he salvaged portions of the chimney and some of the timber, and built his 750-square-foot house in the same footprint.

Hare has yet to spend winter in his new abode, but based on preliminary data and his own calculations, he believes the house will stay around 63 degrees. That’s a level he and his wife are comfortable with, in part because the temperature will be constant with no drafts. The house project is a match for Hare’s ideals. He travels to jobs on a bike, not by company truck, and took his own house as the first project, both to demonstrate these techniques to future clients and to provide for his family.

The key to the house is its ability to retain heat. Hare started with a foot of insulation in the walls and roof. The concrete floors are 2 1/2 inches thick, and its cement-based plaster walls are far denser than drywall - creating a “thermal mass’’ that will act like a heat battery, absorbing heat during the day and slowly radiating it back into the house at night. In the summer, the walls and floor will absorb heat and be cooled at night with natural ventilation. There are three patio doors on the south side and three windows on the north side, located to maximize heating from the sun.

Hot water will come from a tankless heater, a device that takes incoming cold water and heats it up as needed, instead of wasting energy keeping a large tank of water hot all the time. To test for airtightness, Hare used a fog machine and a “blower door test,’’ which pressurizes the house and looks at how much air leaks out. The house turned out to be virtually airtight.

The lungs of the house will be a heat recovery ventilator, a device in the basement that sucks stale, warm air out of the house and injects fresh air from outside. To keep the house warm, air leaving the house will pass next to the stream of new cold air, heating it as it exits. Much of the work takes its cues from the Passive House standard, which certifies that houses are virtually air tight, thereby retaining heat and cutting energy use by as much as 90 percent. But much of the science behind such extremely insulated homes come from New England, where early and iconic work was done in the 1970s, said Paul Eldrenkamp, owner of Byggmeister, a Newton firm that does energy-efficient renovations.

“For the moment, it appeals more to the crusader who has some resources than to the average person, but there are more and more people who instead of going for the luxury kitchen or the master suite addition are more inclined to put that money into a deep energy reduction,’’ Eldrenkamp said. “Partly because, to be honest, in 20 years that luxury kitchen is going to look like a 20-year-old kitchen. But that insulation is going to look like gold.’’

Hare said his small house will cost about $250,000, with costs inflated by the money he spent trying to save the original structure. A second project his firm is building in Jamaica Plain, a gut renovation called the JP Green House, will cost about $225,000, and there are plans to seek certification for it as a Passive House. Generally, Passive House construction costs about 5 to 10 percent more than standard construction, Hare said. While there will be dramatic energy savings in both projects, the homeowners are making a choice based more on their ideals than on economy, and are paving the way for such building techniques to become more standard and familiar. Ken Ward and his partner Andree Zeleska are both climate activists who decided to build the JP Green House because they wanted to do something tangible and show that it could be done within a reasonable budget.

For green renovations to have an impact on the climate, it will require more than just a few one-off projects. William Moomaw, a professor at the Fletcher School at Tufts University, said that was part of the motivation when he built his own superefficient house in 2007 in Williamstown, which uses 14 percent as much heat as a normal house.

“Getting these examples out there is really important, it makes a huge difference,’’ said Moomaw, who was a member of the Intergovernmental Panel on Climate Change, an international panel of scientists that concluded human activity was causing global warming. “A person looked at our house, shook his head and said, ‘I guess if it exists, it must be possible.’ ’’

The state is also examining how it might help encourage more highly-efficient construction. It convened a Zero Net Energy Buildings Task Force focused on structures that are essentially off the grid because they generate enough energy to meet their needs. Ian Bowles, secretary of the Executive Office of Energy and Environmental Affairs, said such efficient buildings are a “beacon on the horizon,’’ something to inspire people and push the building standards forward - while in the short term, homeowners can take advantage of increased energy-savings programs. The technology exists, said Dr. Keith Collins, who just finished spending the first year in his ultra-efficient home in Rockport, Maine, with no furnace. Collins’s home stays comfortable at 68 degrees, heated by the sun shining through the windows and by water heated by solar thermal panels on the roof.

“It’s not like turning on the heat. I remember this in having other houses,’’ Collins said. “ ‘Oh, how late can I go before I have to turn on the furnace?’ The sun comes up everyday; my heater comes on everyday.’’

That may be true, but in Roxbury, Hare’s wife got a commitment from her husband. Damiana Diaz-Reck said that while she is not worried about the approaching winter, she has told Hare that if it gets too cold, she has the right to plug in a space heater.

Carolyn Y. Johnson can be reached at cjohnson@globe.com.