Building in cold climates means building for warmth. Homeownders and commercial businesses spend money keeping their inhabitants warm. Well-designed buildings are buildings that do not cost a lot to keep warm. How can a building owner avoid wasting money on heat?
Hire an architect and a contractor who both are versed at high performance buildings: building in cold climates.
A high performance building is by definition a building that does not require a lot of energy to work. Architects set the parameters that must be met for high performance. Contractors execute those parameters. For instance, an architect may set the wall insulation level at R-40, based on a detailed requirement for a specific wall construction. Nevertheless, those detailed requirement must be constructed. A good contractor will construct what the architect designed. Other contractors may fail to build what was designed.
Together, a good contractor and architect will look at the three ways heat leaves a building: convection, radiation, and conduction. Let’s take a short look at each of those.
Conduction is the flow of heat through solid materials. It is measured through the well-known metric of R-value. We all know about R-19 walls (typical insulation for 2×6 framed walls) and R-38 roofs (typical insulation in 2×12 roofs). The state of the industry today is to acknowledge the short circuits in cavity frame construction, where the insulation is between framing members, and the framing members representing short circuits that cause heat loss. The fix is continuous insulation, or insulation outside the framing cavity. Buildings with exterior continuous insulation lose less heat than buildings with only cavity insulation. Cavity and exterior insulation are not terribly hard to get right, but they do require good craftsmanship.
Convection is the movement of air, and for our purposes we mean air moving through exterior walls. When cold air comes in, warm air leaves. Stopping air infiltration is paramount for energy efficiency, and one of the hardest things to get right, both in terms of design and execution. Architects and contractors both need to be at the top of their game with regard to air infiltration. It helps for them to communicate, on a project by project basis, about the best way to stop infiltration.
Radiation is the flow of heat through space. We see radiative heat loss through windows, or more precisely, through glass. On sunny winter days, letting the sun’s radiation into a house makes sense. Unfortunately, the number of sunny hours available for passive solar heating are nowhere near the number of hours when radiative heat will flow the other way. Good radiative design means using very few windows on the north side of a building, no more than 10 percent of exterior wall area for windows on the east and west sides, and no more than 20 percent of exterior wall area on the south sides. Good radiative practice is largely a design responsibility. The architect must get this right. The contractor has little to do with success in this area.
Thus, building in cold climates to achieve high performance is the result of designers and contractors working together to achieve a desired result. An owner must have an architect who can design a high performance building, and an owner must have a contractor who can faithfully build that design. They both need to understand radiative, convective and conductive heat flows, and they both need to get their responsibilities right.