Le présent document a été élaboré en vue de faciliter la construction industrialisée d'enveloppes de bâtiments à base de bois (murs extérieurs, toits), et donc de répondre aux exigences accrues en matière d'efficacité énergétique.
The overall objective of this study is to provide information to building design practitioners that will help to improve accuracy of hygrothermal models and enable them to better use these models to predict the durability and thermal performance of wood-based building envelopes. To achieve this, hygrothermal models using WUFI Pro software are validated with experimental data obtained from five wood-frame wall assemblies, with different insulation and vapour control strategies, exposed to the climatic conditions of Vancouver from October 2018 to May 2020. This exercise provides a set of model input parameters that the practitioner can use to assess similar structures exposed to similar environmental conditions. Sensitivity analysis is conducted on the model input parameters to establish which are the most important in obtaining a good fit to experimental measurements, and therefore accurate prediction of assembly performance. There is also discussion on limitations of the hygrothermal model.
This study focuses on measuring the wood moisture content (MC), temperature, and relative humidity (RH) (and the corresponding vapour pressure gradients) through each wall assembly to assess its hygrothermal performance. Controlled moisture loads, in the form of vapour
(achieved by maintaining a relatively high indoor RH) and liquid water (achieved by periodically injecting water to the wetting pads installed on the wood panels) are employed to stress these walls for investigating their moisture-related behaviour. After the wall panels and most instruments were installed but with the CLT directly exposed to the interior environment, a high indoor RH in range of 70-80% was maintained, starting mid-December 2020 inside the test hut to condition the wood to achieve comparable moisture gradients among the eight CLT panels. The test walls were closed in with interior framing (and interior insulation of walls No. 1 and No. 2) and drywall installed, followed with interior finishing in late January 2021. The indoor RH was afterwards set to be around 50%. Water injection is planned to start in the summer of 2021. Test results and performance of these walls will be presented and discussed in future reports.