Methodology for selecting fenestration systems in heating dominated climates

Selecting optimum windows in heating dominated climates is a complex task because of the inherent trade-off between their U-value and solar heat gain coefficient. In addition, the use of shades is known to reduce heat losses, but they are rarely selected for this intent and considered as an integrated fenestration system at the design stage. This paper presents a method for selecting optimum fenestration systems (windows with shades) to maximize the annual net energy balance. The method has the capability to simulate a one or two layer shading system with one exterior and/or one interior planar shade(s). This methodology generates 2D schematics indicating the net energy balance of different fenestration systems. Such schematics are useful at an early design stage when there is a need to compare different design options for different orientations on a relative basis.Diagrams are presented for five glazings with an interior roller shade, an exterior roller shutter and a combination of both, for the four cardinal orientations for the city of Montreal, Canada. A comparison of simulated and experimental U-values of four shading devices indicates results reasonably close to each other.