Visualizing the impact of Thermal Bridging on the design of High Performance Buildings StĂŠphane Hoffman Morrison Hershfield
December 4th, 2015
Thermal Bridging
ASHRAE 1365- RP 2
BC Hydro BETBG
Presentation Overview
1 Thermal Bridging 101 2 Data & Findings 3 Applications
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Thermal Bridging 101
Effective Thermal Resistance What is a Thermal Bridge? • Highly conductive material that by-passes insulation layer • Areas of high heat transfer • Can greatly affect the thermal performance of assemblies
Parallel Path Heat flow
Utotal
Area weighted average of un-insulated assemblies 6
Addressing Lateral Heat Flow
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Overall Heat Loss
Q
Qo
Qslab
Additional heat loss due to the slab
Overall Heat Loss
Ψ = Qslab / L The linear transmittance represents the additional heat flow because of the slab, but with area set to zero
The Guide
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Applications Evaluating Impact of Details
Determine Whole Building Heat Loss Corner Shelf angle
Parapet
Window Transition Slab
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Heat Flow Summary Example
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Opaque Wall Thermal Performance Summary Example
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Visualization Tool for Parametric Modeling
Parametric Visualization Tool
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Parametric Visualization Tool
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Parametric Visualization Tool
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Parametric Visualization Tool
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Parametric Visualization Tool
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Parametric Visualization Tool
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Parametric Visualization Tool
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Parametric Visualization Tool
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Future Trends
The Future • Increasingly difficult to ignore thermal bridging at intersections of assemblies • Move beyond simply adding “more insulation” • Better able to account for thermal performance of envelope
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Questions