This Major Research Project focuses on reducing the linear thermal bridging coefficient (ψ-value) in junction details in Passive Houses in North America.
By analyzing a sample of details from existing Passive Houses in North America, the range of ψ-values was found to be between -0.154 and 0.124 W/mK.
A process was outlined to lower the ψ-value in junction details. Strategies that can be used to reduce the ψ-value include: localized overcladding, thermal breaks, alternative material, and alternative construction. The first and last strategies were found to be most effective at reducing the ψ-value.
Comparing the results of PHPP simulations for several houses, with and without linear thermal bridging, showed that the impact on the specific heating energy intensity can be large. The PHPP models showed that savings of 6-25% on the specific heating energy intensity can be achieved by applying the reduction process to details above 0.01 W/mK.