Without a lot of cut-outs or complex angles, simple shapes are also easier to insulate and air seal. If you choose the simplest house shape that works for you, your construction costs are lower, and your sustainability goals are easier to reach.

2. Insulate the foundation and slab thoroughly

Contrary to the popular saying, heat doesn’t just rise. It goes out through every surface of the house, including the bottom. The new super-efficient homes have thick insulation around the foundation and slab, and this home is no exception. Under the slab is 8 inches of rigid expanded polystyrene insulation.

The basement walls are made of insulated concrete forms (ICF). Still, they’ve got an extra layer of 4-inch expanded polystyrene foam wrapped around the outside for a total effective insulation value of R-60.

3. Build Thick Walls

The walls of this house are 16 inches thick. It’s got two walls – a structural wall on the inside and a thick wrap of insulated, non-structural wall on the outside. The inside wall is 2 x 6 wood frame construction, insulated with mineral wool batts, quite normal for a house these days. But what happens after that is the amazing part. A second wall will be attached around the exterior.

The outside layer is made of Larsen trusses, a lightweight wooden truss made to hold a thick layer of insulation – 10 inches thick in this case. The Larsen truss is an ingenious structure invented in 1979 by John Larsen, a renovation contractor in Edmonton, Alberta, Canada. It is now used for super-efficient homes in cold climates around the world. In the next photo, the Larsen trusses have been installed over the surface of the walls, surrounding all the window boxes.

The outer wall of Larsen trusses was filled with blown-in cellulose insulation, which is made from recycled newspapers and provides a thick, dense layer of insulation. The outer layer was sheathed in plywood, with 1/8 inch gaps between the plywood pieces to allow humidity to escape the wall. Then it was wrapped in house wrap to provide the wind barrier.