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AUGUST 2017 | 13 Building Envelope RENDERING COURTESY STANTEC ARCHITECURE LTD. IN ASSOCIATION WITH TEEPLE ARCHITECTS INC.; PHOTO COURTESY CPCI T Highly efficient building envelopes are key to meeting new standards by ROBIN BRUNET The word "holistic" may be overused as a definition of considering something in its entirety, but it perfectly describes how building energy efficiency in Canada is approached in 2017 – with envelopes seen as the key element in achieving that efficiency. Nick Trovato, corporate practice director for RJC Engineers' building science and restoration prac- tice, says, "Increasingly, we're being sought at the design stage by clients who realize the importance of energy efficiency and who regard it as, among other things, an opportunity to improve building perfor- mance, reduce environmental impact and improve occupancy comfort." But as with so many developments in the building trade, the impetus for achieving new levels of energy efficiency – and accompanying improvements in building envelopes – is driven not by market needs, but government regulations. However, in reference to the two standards of ASHRAE 90.1 and NECB being adopted by the provinces (ASHRAE for B.C. and NECB for Alberta), Trovato says, "There have been changes to the building codes in different regions, and I think their mandatory application is a positive step, pre- cisely because they focus on the total building and not just individual elements. Similarly, while thermal performance and leakage was cause for concern in the past, these elements weren't necessarily linked to a building's energy performance." NECB is particularly interesting in that provinces that adopt the standard have three ways to achieve energy efficiency: a strictly prescriptive path where minimum performance requirements for various com- ponents are identified and must be met (standards such as R-27 walls required in Edmonton, for example); a trade-off path where performance can be reduced on some components by trading for improvements in other components to achieve the desired overall result (more walls and less glazing to reach a certain R-value); and energy modelling whereby building com- ponents (envelope, mechanical and electrical system) are placed in the computer model and modifications can be made to achieve the required performance. Further regulatory developments in 2017 place more focus on building envelopes, such as LEED v4, which now offers points for their more stringent design and building commissioning. "Highly-efficient building envelopes are also a key to the success of Passive House design and net zero facilities," says Trovato, adding that RJC is currently involved in the development of a fire hall in the Vancouver area using Passive House principles. RJC is also involved in the spectacular redesign of Edmonton's Stanley A. Milner Library, a project that involves the replacement of the building's 1960s pre- cast concrete envelope in order to improve thermal performance and significantly reduce energy con- sumption. Engineered Assembles also worked on this project, supplying engineering assistance on spacing of its thermally broken clip, TcLip (see below). Brian Hall, managing director for the Canadian Precast Prestressed Concrete Institute (CPCI), reports that total precast systems as building envelopes are becoming more prevalent, especially in Ontario with The Barrel Yards Point Towers in Waterloo being a prime example: the two 25-storey towers were orig- inally designed as cast-in-place structures with pre- cast and window wall cladding, but midway through the design phase the owner requested a move to total precast starting at the fourth floors – and the result has been a big cut in construction time. By combining many precast elements to produce a complete structure, precast concrete's benefits are maximized. "In terms of cost elements, a distinct advantage of precast concrete over other building sys- tems is speed of delivery and ease of installation, ser- vice and support," says Hall. "All contribute directly to lower total cost of ownership, especially when pro- duced in CPCI-certified plants that boast the additional benefit of higher quality." It's A Wrap Stanley A. Milner Library, Edmonton, AB The Barrel Yards Point Towers, Waterloo, ON

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