Issue link: http://digital.canadawide.com/i/423872
and systems should be avoided. Ten-year shingles, sometimes used for small walk-up apartments and similar buildings, are one example. Another that Smith points to is the window wall system, introduced in the 1980s as a less costly alternative to curtain wall. The Calgary-based engineer says that in Southern Alberta, where freeze-thaw cycles are growing more frequent as the climate changes, window wall can be a poor choice. "The primary system gasket cannot be replaced, so it will have to be repaired with caulking about every seven to 10 years. Relying on caulking as any kind of a face seal is a bad idea. In Calgary's climate, it can't last," Smith says. He points to a mix of window wall and curtain wall in Calgary and notes that the latter is both easier to install and repair, built to higher standards and more durable. Smith adds, "New codes are going to limit window area in future." Buildings need to be designed holistically as complete, integrated systems. An ideal type of city building, whether for offices or residential, Smith says, is six- or seven-storeys high and clad with a durable product like brick. The height of no more than six or seven floors ensures that refurbishments and HVAC upgrades can be done easily. "A retrofit solution for older buildings, with brick or concrete cladding, that are poorly insulated, or heritage buildings, is to build an airtight box inside," he says. The challenges to implementing the kind of rational measures for durability that Smith and others advocate have to do with the way in which a building gets built. "We don't have benchmarks for new high-rises related to sustainability. Many new buildings fall short in this area. This is as a result of a design process that aims at the lowest cost. The P3s are driven by capital cost and price, and are a potential risk to durability. And for them as well, we don't have benchmarks to address durability," says Kevin O'Neill, the commercial division director at HH Angus & Associates Limited. He points to a cluster of low-hanging fruit-type strategies for improving energy efficiencies. They include switching to low- temperature water for heating, use of LED lighting and capturing rainwater for toilets and non-potable applications. Also, "There's lots of heat recovery opportunities from existing HVAC systems," he says. More complicated options can involve the transfer of heat between buildings situated within a mixed-use complex or the installation of ground-source heat pumps in high-rises. Adaptive facades that include shading devices on the exterior that respond to conditions are also starting to be used. "But these are still expensive as they are very new," says Vaidila Banelis, senior partner at Zeidler Partnership Architects. George Steeves, principal at Sterling Cooper Consultants Inc. agrees that large high-rise buildings "need not be energy hogs." There are many simple methods by which the new building code and sustainable energy targets can be easily met. "The new 65-storey Trump Tower being constructed in Vancouver recovers waste heat from the elevator machine rooms and electrical rooms," explains Steeves. "It uses this heat to preheat domestic hot water with the result being that up to 50 per cent of the energy required to heat domestic hot water is now free waste heat. The capital cost of recovering heat in this manner was $46,000 with payback in under three years." Solar panels have also been used on the Tower to provide further supplemental heat for the domestic hot water, but these panels are relatively small as the waste heat recovered from service rooms has already reduced the energy needs of the domestic hot water. Steeves adds that building stack effect is greatly reduced by limiting the relief of air to the outside through stairwells, stairwell doors, elevator shafts and all openings to the outside on the roof. "The payback on this item was under a year. Both of these solutions are simple, cheap and greatly improve the building energy consumption values," explains Steeves. "The building construction and operation industry must develop simple methods to save energy as was the case for the Trump Tower. Highly complex mechanical systems, such as those now being designed for some LEED buildings, are not being, and in many cases cannot be operated to the expected efficiencies." According to the RAIC, by 2035, nearly three quarters of all buildings in Canada will have either been built or renovated in the previous quarter century or so. It is a great opportunity to deal with greenhouse gas emissions, the RAIC says. "If you're doing a retrofit anyway, say, because of a leak, you can see it as an opportunity to upgrade. The payback starts to look sensible as you've already had to pay for labour to take the wall apart," says Alex McGowan, VP technical services at Levelton Consultants Ltd. n Green building design 20/ december 2014