Cottaging Off the Grid
For Joe and Carolyn Johnson, the culmination of their new cottage construction project came last June when the men arrived to cut off their electricity.
Written by: Jacquie Johnson
Photos by: Randy Romano
Joe and Carolyn Johnson began designing their new solar-powered cottage from the ground up in January 2002. An engineer by profession, Joe planned to do most of the design himself and expected it to be complete by the end of February 2004.
But as the deadline approached he was still pondering the roof, having been encouraged by some of his colleagues to “think big” and install a cathedral ceiling with no central support. He also had to design around solar panels, minimal energy consumption, high ceilings and good ventilation. At this point, “the engineer began to take over, and I became fascinated with the structural solutions to this problem,” he says.
The solution he chose was a series of hip beams, sloping from the corners of the roof to a central
apex, held together by a compression ring at the top and a tension tie at the bottom, running around the top of the walls. As the weight of the roof forces the beams to spread outwards, the tension tie counter forces them inwards. As long as the two competing forces are balanced, the building doesn’t fall down.
Peter Head, owner of Headstart Construction in Orillia, Ontario and chief contractor for the project, compares the roof to a wine barrel. The tension tie on the roof keeps it from falling down in the same way that the steel band around a barrel holds the whole thing together and keeps it from exploding under pressure.
Another important element of the design was a high insulation R-value to minimize the need for heating in the winter and air conditioning in the summer. To achieve this, Joe used structural insulated panels, an innovative type of roof panel made of sandwiches of oriented strand board with expanded polystyrene (EPS) in the middle.
Meanwhile, the walls were constructed of insulated concrete forms – sandwiches of EPS with poured concrete in the middle – which have a high R-value and are strong enough to hold up the roof. In his experience, says Head, this was the first time anyone had attempted to build a structural concrete column within an ICF. To accomplish the design, he had to build a steel cage, then build the ICF wall around this cage with the steel rebar reinforcement extending up through two concrete pours, one for the basement foundation and a second for the main storey.
The design is innovative inside as well. In the summer, the building is ventilated by a large number of windows and several skylights. Since heat rises and accumulates in the high ceilings, the skylights facilitate its escape through the roof. Fans and internal windows installed near the ceilings channel hot air toward these escape routes.
During the colder months, heat is provided by a high-efficiency wood stove and a propane-powered, forced-air furnace. The spare bedrooms and the basement, rooms not used regularly, are separated from the rest of the house with extra-insulated walls and doors so they can be sealed off.
The piece de resistance is the four solar panels on the south side of the roof that can be adjusted during the winter to match the sun’s lower position in the sky. Through them, the sun charges a large bank of batteries in the basement, which can be drawn on when it rains or clouds over. A back-up diesel generator can be fired up during exceptionally bad weather.
The demands of solar power were the driving force behind this project, says Head. It was designed entirely around energy efficiency, including the ICF construction and high-efficiency Thermapan ceiling panels. Even the elevation of the property and the angle at which the house faces the sun were taken into account. Headstart Construction builds one full ICF house per year, plus several homes of traditional construction. Head says the energy efficiency trend started about four or five years ago and is steadily increasing. It is especially important to his business because he often works in remote areas and on islands. When oil and propane have to be brought to the site by boat, efficiency becomes crucial. Peter and Stephen Head and their crew opted to do most of the work themselves, rather than calling in subtrades. That included the excavation and the demolition of the old cottage and installation of the floor slabs, drains, walls, columns, beams, roof panels, siding, internal partition walls, windows, doors, skylights and floors. Although not a specialist in the installation of alternative construction materials at the time, Peter was always open-minded and willing to learn and experiment, the Johnsons say. Although the Johnsons’ new cottage is not quite as spectacular as the Millennium Dome or the Millau Viaduct, they find it both beautiful and functional. Inveterate putterers, their biggest challenge may be making the time to sit down with a glass of wine and admire their handiwork.
If you are planning an environmentally conscious renovation or construction project, do lots of research in advance to ensure it fits your budget and lifestyle. Home and cottage trade shows are a good place to get some ideas.