BC Business
More and more B.C. companies are thinking green these days, which is evident in the design plans of new office buildings. In the past, figuring out exactly how to calculate energy performance of a structure was challenging. It’s difficult and time consuming for building designers to accurately calculate the thermal performance of building envelopes owing to thermal bridging—pathways of high heat flow through walls, roofs and other insulated building envelope components that allow the heat flow to bypass the insulating layer, effectively defeating the purpose of the insulation. But with the creation of the Building Envelope Thermal Bridging (BETB) Guide the road to designing and building an energy-efficient commercial office tower is becoming easier to find. The BETB guide is broken into three parts: Building Envelope Thermal Analysis Guide; Energy Savings and Cost Benefit Analysis; Significance, Insights and Next Steps. It’s primary goal? To help the B.C. construction sector design and build more energy-efficient buildings by providing easy-to-use methods for understanding and mitigating thermal bridging. Heat loss and air leakage across the exterior envelope can account for over 50 per cent of the total energy load. For these reasons “we advise building design practitioners that their top priority is to reduce energy loads in their buildings before implementing other measures to reduce energy consumption,” says former energy modeller and current BC Hydro Power Smart specialist engineer, Bojan Andjelkovic, who originated the idea for the guide. “We also advise them that constructing buildings with thermally resistant, airtight envelopes should be considered job one.” According to Gordon Monk, BC Hydro Power Smart engineer and project manager for the guide, the BETB guide is a reference for all building types, offering illustrations that depict how actual building heat loss can be up to four times greater than is generally accounted for in conventional design practice (due to thermal bridging at envelope component interfaces). From the catalogue of the thermal performance (the effective R-values) of more than 230 envelope assembly details commonly used in this province to evaluating the costs associated with improving the thermal performance of opaque building envelope assemblies in B.C.’s three different climatic regions to insight on how design practitioners might use information on thermal bridging in both design and high-performance building simulations, the BETB guide is the one-stop source for professionals in the design sector. “Architects, modellers and envelope specialists can now refer to the catalogue and look for the assembly details they would like to use,” says Oscar Ceron, Manager of BC Hydro’s Power Smart New Construction Program. “They will then be able to more accurately and easily account for the building envelope thermal performance in their modelling and building practices. This in turn will support Power Smart’s goal to help transform the B.C. marketplace to the point where all new buildings are designed and built to the highest standards of energy efficiency.” Officially launching on October 16, followed over time by workshops to help practitioners become comfortable with how to use this tool and ensure they have a firm grasp of all the information included, Ceron is realistic about the fact that there will be a learning curve for those who will benefit from the guide the most. “This [BETB guide] is not something that can be digested overnight, so for now we encourage its use as an optional part of the project submission, and we are allowing some time for the market to incorporate it into practice.” But once the guide is absorbed and put into practice on a regular basis, there will be a positive impact on both the building and its occupants. “Mitigating thermal bridging has other benefits beyond reducing building heating and cooling loads. It can also increase thermal comfort and air quality for building occupants and, by reducing condensation, it can also lead to a longer life for the building envelope,” explains Andjelkovic. Also celebrating this new tool is the City of Vancouver. “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,” states Greg McCall, the City’s Energy Policy Specialist. “Its approach and accuracy lends itself to be a critically useful tool, not just in B.C., 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.” To download or find out more about the Building Envelope Thermal Bridging Guide, go to bchydro.com/thermalguide.
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