Hygrothermal performance of bio-based insulation material in wood-frame walls exposed to unintended moisture sources

The attention for energy performant buildings with a low environmental impact has been growing over the years and as a result, the use of bio-based insulation materials as well as wood frame constructions has become more and more prevalent in Belgium and Europe. This research assesses the hygrothermal behavior of bio-based insulation materials, used in wood frame walls. The study concentrates on their durability and thermal performance, when exposed to unintended moisture sources. Two different leakages are looked at: one originating from imperfections in the weathering sealant at the exterior, and a second is introduced due to insufficient air tightness at the interior, causing infiltration of humid indoor air into the wall system and the occurrence of interstitial condensation. Primarily results show the dominant impact of the ventilation rate in the cavity between the masonry outer leaf and the wood frame wall, on the durability and the thermal performance of the structure. Also, there is higher negative impact by exterior leakages on highly absorptive bio-based insulation material compared to the traditional mineral wool setup. Peer-review under the responsibility of the organizing committee of the ICMB21.