RDH Building Science,
    RDH Building Science

Improvements in building efficiency can significantly reduce carbon emissions and are an intrinsic component in greenhouse gas reduction targets. The Passive House concept provides a framework for high-performance building that is growing in popularity in Canada, and particularly in the Pacific Northwest. The Passive House standard requires its buildings to achieve specific performance values for heating energy use intensity, total energy use intensity, spatial temperature variation, heat recovery ventilation performance and air leakage rate. The promised co-benefits of Passive Houses include superior thermal comfort and indoor air quality.

Passive House design is not prescriptive and can incorporate many different design aspects. The wall assembly is no exception. This paper evaluates the hygrothermal performance of a deep-stud wall assembly of a Passive House in Victoria, BC, with regards to moisture durability. The concern with deep or doublestud wall assemblies is the combined effects of reduced drying with wall configurations that place moisture sensitive materials in riskier locations. Consequently, enclosure monitoring was undertaken in an occupied six-plex over the period of one year.

The enclosure monitoring sensor packages were installed in strategic locations in the wall assembly to monitor the conditions of the assembly. The assemblies were evaluated based on the results of an empirical mold risk index. The wall assembly appears to perform acceptably, with minor concerns of mold growth on the North wall. Air leakage is a significant concern for cavity insulated walls, but the airtightness requirements of Passive House minimize this risk.

Presented at the 15th Canadian Conference on Building Science and Technology.

View presentation slides here.