INNOVATION September-October 2014

quality for building occupants and, by reducing condensation, it can also lead to a longer life for the building envelope.” The guide is broken into three stand-alone parts. Part 1 is the “Building Envelope Thermal Analysis Guide.” This is a catalogue of the thermal performance (the effective R-values) of more than 230 envelope assembly details commonly used in this province for buildings of all types—from single family and row houses to high-rise MURBS and commercial office towers—and provides ideas for how they can be enhanced to minimize thermal bridging. The thermal analysis is exact: the software Morrison Hershfield used to analyze building as- semblies is a commercial version of the life-or-death software used by NASA for analyzing heat flow on the space shuttle as it re-entered the Earth’s atmosphere. “Architects, modelers and envelope specialists can now refer to the catalogue and look for the assembly details they require,” says Oscar Ceron, manager of BC Hydro’s Power Smart New Construction Program. “They will then be able to more ac- curately and easily account for the building envelope thermal performance in their modeling and building practices. This in turn will support Power Smart’s goal to help transform the BC marketplace to the point where all new buildings are designed and built to the highest standards of energy efficiency.” In the past, says Andjelkovic, “in the absence of relevant resources, modelers often used nominal R-values in ASHRAE and other standards, which lead to us overestimating the performance and underestimating the heat loss by as much as a factor of three. And there’s a big difference between R-13 and R-3.” Perhaps the biggest leap forward, he adds, is in “wall-to- window transitions. Before this guide, they had never been accounted for and it turns out they have a significant impact on overall building performance.” Part 2 of the BETB Guide provides an “Energy Savings and Cost Benefit Analysis” so regulators, researchers and anyone else who’s interested can evaluate the costs associated with im- proving the thermal performance of opaque building envelope assemblies against forecasted energy savings for eight building types in BC’s three different climatic regions. Part 3, called “Significance, Insights and Next Steps,” dis- cusses how design practitioners, as well as government and utilities, might use this information on thermal bridging in both design and high performance building simulations, and in new building codes and bylaws. The guide’s official launch on October 16 will be followed by workshops to help practitioners become familiar with this latest tool. Eventually, use of the guide will become a manda- tory part of applying for the BC Hydro New Construction Program. “We recognize,” says Ceron, “that this is not some- thing that can be digested overnight, so for now we encour- age its use as an optional part of the project submission, and we are allowing some time for the market to incorporate it into practice.” It is optional, but highly encouraged, for new construc- tion within the City of Vancouver, too. “In 2013,” says Greg McCall, P.Eng., Vancouver’s energy policy specialist, “we began asking all new construction

applicants to voluntarily determine their building’s overall energy performance, in the form of effective R-value, so that envelope specialists could get a sense of one building’s envelope design with respect to another. As of January 1, 2015, the dec- laration of the building’s effective R-value will be a requirement for a building permit, so the timing for introducing this tool could not be better. Although we are not making the use of the guide mandatory, and projects are not limited to the assemblies found within it, using the guide is undoubtedly going to save applicants days of work, while greatly increasing the accuracy of their assessment.” McCall continues, “The City of Vancouver recognizes the significance of the BETB Guide as a tool that could influence the industry and policy makers, and even those developing the next level of energy standards and codes. Its approach and ac- curacy lends itself to be a critically useful tool, not just in BC, but across the nation and even south of the border. In a world where energy performance is increasingly becoming a priority, this tool will undoubtedly affect positive change in building envelope design and performance wherever it is used.” BC Hydro’s Gordon Monk believes the guide is one of the most significant energy-efficiency initiatives he’s been involved with throughout his long career. “It’s a major piece of work,” he says. “There has been a North America-wide gap of infor- mation about thermal bridging, not just about how it affects energy efficiency but its impact on the overall quality of the building envelope as well. And it will make life quite a bit easier for engineers, archi- tects and anyone else involved in new building design, adds McCall. “It used to take me two whole weeks to calculate the performance of a building envelope, with plans all over the floor, colour crayons everywhere. Fast forward to today and BC practitioners now have access to the latest in modern technol- ogy to calculate energy performance in far less time and with far greater accuracy.” More information about the Building Envelope Thermal Bridging Guide and upcoming workshops for design practitioners can be found at www.bchydro.com/construction. v

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