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1.5 ConEd Learning Hours
This presentation will review interconnections between snow and ice formation patterns on facades and energy efficient façade details. There is a growing awareness in the design and construction industry that the thermal performance of building envelope / façade details can be dramatically lower than previously assumed. Consequently, in some instances, poor thermally performing details are being replaced with improved, more energy efficient details sometimes combined with high performance glazing systems and building HVAC strategies. Improved thermal performance for our new and retrofitted buildings is certainly a necessity, but can have unexpected consequences for snow and ice formation on building exteriors that need to be considered.
In cold climates, poor thermally performing envelope details readily transfer heat from the interior conditioned space to the exterior surfaces of the building envelope, resulting in exterior surface temperatures that can reduce the formation of ice and snow on a building surface. With the adoption of improved energy efficient assemblies and HVAC strategies, heat transfer is reduced to varying degrees to improve the building energy performance. The hypothesis is that the resulting change in localized exterior surface temperatures is altering the anticipated ice and snow formation and transformation patterns on buildings in cold climates. Interesting situations are emerging where the reduced heat transfer is permitting snow and ice to form and accumulate in areas where traditionally, there was enough heat loss to prevent this from happening. This session will compare a sampling of building specific ice and snow formation on existing high rise buildings in North America with predicted heat transfer for traditional and higher performance building envelopes.
Overall heat transfer through envelope assemblies, as well as through specific building envelope details will be considered. Examples of envelope assemblies that are at risk for increased ice and snow formation due to reduced heat transfer will be presented.
Peter Adams, P.Eng., is a Principal of Morrison Hershfield Limited and a Senior Building Envelope Engineer based in the firm’s Toronto office. A graduate of mechanical engineering from Memorial University of Newfoundland, Peter began his building science career over twenty years ago at the National Research Council in Ottawa. He has since investigated and devised repairs for hundreds of buildings experiencing envelope failure and indoor air quality problems throughout North America, and provides building envelope design assistance for retrofit and new construction. Peter is Past President of the Ontario Building Envelope Council, participates in several industry organizations, and is currently Vice Chair of ASHRAE Technical Committee 4.4 on Building Envelopes and Materials.