Building sciences professor John Straube speaks to CSC Canada conference Windows and energy savings: The weakest link in Canadian buildings John Straube Canadian Design and Construction Report staff writer Where is the weakest point in energy savings in Cana- dian buildings? John Straube, a University of Waterloo engineering professor, indicates that windows, even ones marketed for their high-efficiency – leak energy at an incredible rate, and less-than-perfect fenestration solutions could defeat other energy-saving efforts, including wall and ceiling insulation. “What's really damning is that older buildings, built well before the Second World War, are pretty good in terms of energy consumption,” he told the annual Con- struction Specifications Canada (CSC) conference in Kitchener in May. As an example, the university's School of Architecture building, constructed in the early 1920s, uses “significantly less energy than the average.” “The walls are made of solid masonry,” he said. “There are decent windows – but not too many of them.” Yet the building is “filled with natural daylight.” Compare this construction to modern, mass-market urban condos in Toronto, with floor-to-ceiling glass cur- tain wall facades. These may look nice, and help sell the condos, but the owners will be stuck with the energy bills – and pos- sibly hefty maintenance charges – for years and years. Straube, in an earlier CBC interview, said a building is a living, breathing thing, enclosing and protecting the people who live inside. “Building with glass walls is to miss the main point of a building . . . sacrificing the pro- 4 – Summer 2014 — The Canadian Design and Construction Report tection that is a building's first duty for a beauty that is only skin deep,” CBC reported. “It's almost derogatory in my world to forget about everything else that's part of experiencing a building,” Straube was quoted as saying. “I like to think what is the building going to be like on a dark and stormy night. In our climate, particularly, we care about that. It's life and death.” Simply put, he told the national CSC conference, many commercial buildings have really “poor enclo- sures” with exceptionally low insulation R-values, caused by “too much glazing, too many thermal bridges, and too much air leakage – which no one seems to measure.” Meanwhile, heating and ventilation systems have been designed with super-efficient equipment, but “the systems are often very inefficient.” The result, windows, even with double-glazing, often have absurdly low R-values, perhaps at 2 or maybe 3. If these window systems dominate the building, even the best insulation within the walls won't do much to solve the problem as thermal bridging gobbles up wall and ceiling insulation value. For example, if wall systems have an R20 level (over 50 per cent of the area), and there are R2 windows cov- ering the other 50 per cent, the overall building insulation value is just R3.6. Assuming really good windows are installed, with an R4 value, then the building gains some ground, but the overall insulation factor remains what would seem to be a dismally low R6.6.