In this area of New England it is common for wood-heated homes to burn six, seven or even eight cords of wood a year. But Jonathan and Marsha Nourse get shirt-sleeve comfort and do all their cooking on a mere two cords.
The Nourses live in a passive solar collector; in other words, the collector doubles as a home.
The collector is called a Trisol because it is shaped like a triangle and 75 percent of the heating comes from the sun. It is so efficient that even when the couple left on vacation for a week in the winter of 1979, the sun's rays alone never let the home drop below 59 degrees F.
That is the sort of economical performance that leads Nourse to believe he lives in a home destined to be the wave of the future.
Fact: It was no more expensive to build than a conventional home. Indeed, at $45 a square foot it turned in at $3 a square foot under conventional costs in the area. The design is such that a more economical version can be built for $33 a square foot -- half that if the owner does the construction himself.
Fact: The passive solar structure requires no motors or other machinery to be effective.
Fact: The massive reinforced walls (60 cubic yards of poured concrete) needed for the adequate heat storage, along with the surrounding earth berm, make the basic structure almost indestructible.
"Given a direct hit in a nuclear attack," says the designer, Leandre Poisson of Harrisville, N.H., "all that would go is the (wooden) second floor." He's jesting, of course, but it makes the point. The banks love the concept; their mortgage money couldn't be safer.
Fact: The same convection currents that heat the house in winter also cool it in the summer. While winter heating costs are minimal, summer air conditioning costs are nonexistent.
The Nourses say temperatures consistently stay 10 degrees cooler than the hottest outdoor temperatures in summer.
The Trisol essentially is an isosceles triangle with a 90-degree angle at the back and two 45-degree angles in front. The rear of the home points as close to due north as possilbe, so the largely glass-filled front wall faces the sun all day. There are no windows in the two side walls.
The roof rises slowly from the front to the rear point. This means that rising hot air streams to its rear high point in the winter, then is forced by a duct back down into the home, setting up a constant circulation of warm air.
In the summer an open hatch allows the warm air to be vented out via a wind turbine. At the same time this venturing draws outside air into the house through two underground pipes, which are buried in the always cool soil of the earthern berm.
Having the floor with the title or slate overlay be thick concrete, as are the ground-floor walls, provides the considerable thermal mass needed if a solar home is to prove effective. It does this by radiating back the stored heat from the winter sun by soaking up unneeded heat from the air in summer.
In the Trisol, the concrete walls are insulated with polystyrene sheeting on the outside and then are backed up with a berm of soil. This does two things: The insulation prevents the loss of heat from the walls into the surrounding berm, while the berm surrounds the home with a cool but stable temperature (about 48 degrees F.) all year round.
Around Jan. 15 when average temperatures reach their seasonal lows, the angled sun streams in to strike all thermal walls as it travels across the southern sky. This is possible because of the triangular shape. The rising sun in the east hits the interior west wall; the setting sun, the interior east wall. At midday all the walls receive the impact of the sun.
In fact, at this time of year nearly all of the sun's rays striking the home, except for those hitting the roof, do so where the radiant heat can be absorbed and stored. In summer, when too much warmth could be a problem, the sun is so high that it penetrates only a few feet into the home.
On the face of it a triangular home seems odd. But this is less obvious inside than out. In fact, the house is a square that has been cut diagonally in two.
Thus, many of the rooms and living spaces leading out from the conventionally angled rear walls are square or rectangular in shape.
The Nourses had begun to think of building a home about seven years ago, "when the first oil crunch hit home." This made them rethink the sort of house they wanted. They were ignorant of solar energy at the time but, in their own words, "We wanted a custom-designed home that would function in this region; that would work with little energy input."
Their search along these lines led them to architect Poisson of the Harrisville-based Solar Survival Inc. His response was to design a solar collector, which he than made habitable. The result was the Trisol, a design that had begun taking form in his mind some years earlier.
The Nourse home was his first Trisol. Since then four others have been erected or are nearing completion. Other custom designs are on the drawing boards. Poisson also encourages people to build their own homes. Fully half the cost is in labor, he says.
Plans are available for 1,200-square-foot units with two bedrooms, one bath, solar greenhouse and root cellar. Write to Leandre Poisson, Box 275, Harrisville, N.H. 03450.