A while back I received a copy of a recent ASHRAE research report (RP-1365) titled Thermal Performance of Building Envelope Details for Mid and High-Rise Buildings. A colleague of mine, Mark Lawton, from Morrison Hershfield’s Vancouver office, had sent me the report and I have two things to say about it: first, the building science research is exemplary; and second, thermal bridging in most common building assemblies is very significant and often reduces the effective thermal resistance of wall assemblies by more than 50 per cent. It’s what most building scientists have had a gut feeling about for a long time now, and Mark Lawton’s study confirmed our worst fears – much of the insulation we provide in our building envelopes is bypassed through thermal bridging.
Energy efficiency aside, the report also provided temperature indices at key locations of the building enclosure, and it became obvious the interior surfaces were often cold enough to support condensation, and hence the potential for mould growth. And the interstitial temperatures definitely indicated a high likelihood of air leakage leading to condensation and subsequent moisture damage. Thermal bridging is not just compromising energy efficiency, but also involves health and durability issues in our cold Canadian climate.
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How to Arrive at the True Value Propositions of EIFS
from the column on the right.