Impact of future climates on the durability of typical residential wall assemblies retrofitted to the PassiveHaus for the Eastern Canada region

Attention to the global warming has influenced many aspects of human activities. Worldwide effort toward energy consumption reduction in building sector is one of the areas affected by climate change. Building regulations demand the building construction industry to be more energy efficient. Studies have been carried out on the thermal performance of energy efficient buildings under future climates, while studies on the durability of energy efficient building envelopes over future climates are limited. This study assesses the impact of future climates on the durability of typical Canadian residential wall assemblies retrofitted to the PassiveHaus over the current, 2020, 2050, and 2080 climatic conditions for Montreal. The durability performance is evaluated in terms of the frost damage risk of bricks and the biodegradation risk of plywood sheathing through simulations using WUFI Pro program. The future weather files are generated based on weather data recorded at the Montreal International Airport weather station using General Circulation Model HadCM3 based on the A2 emission scenario by the Intergovernmental Panel on Climate Change. This study concludes that upgrading wall assemblies to the PassiveHaus recommended level would increase the frost damage risk of bricks, however, this risk would decrease under 2080 climatic conditions. While the decay risk of the plywood sheathing would decrease, the mould growth risk defined by RHT criteria would increase over future climates. Under future climates, mould growth risks of the plywood defined by the mould growth index exist only when rain leakage is introduced and would likely decrease for the double-stud assembly.