In-Situ and Predicted Performance of a Certified Industrial Passive House Building under Future Climate Scenarios

Abstract

The Wood Innovation Research Lab was designed as a low energy-use building to facilitate the construction and testing of engineered wood products by the faculty and staff of the Master of Engineering in Integrated Wood Design Program at the University of Northern British Columbia in Prince George, BC, Canada. Constructed using a 533 mm thick-wall and 659 mm flat roof assembly, it received certification as Canada’s first industrial facility built to the International Passive House standard. Temperature and humidity sensors were installed in the north and south exterior wall assemblies to measure long-term hygrothermal performance. Data collected between 2018–2020 shows no record of long-term moisture accumulation within the exterior assemblies. Data collected during this time period was used to validate hygrothermal performance models for the building created using the WUFI® Plus software. Long-term performance models created using future climate data for five cities across Canada under two global warming scenarios shows favorable results, with an increase in average annual temperatures resulting in lower average relative humidity values at the interior face of the exterior sheathing board in the exterior wall assemblies.

Hygrothermal response of a wood-frame thick-wall assembly to rainwater wetting under future climate scenarios in Canada

“…Due to the 1D nature of the simulations, non-continuous members such as studs are omitted from calculations, which may result in outputs that differ from in-situ performance of the assembly at these locations. Further description of the construction and reported performance of the WIRL building for the 21 month period beginning in 2018 can be found in (Conroy et al, 2021).…”

“…The authors conclude that all climatic parameters need to be taken into consideration before drawing conclusions about the predicted performance of an assembly under future climate scenarios. A similar investigation was undertaken by Conroy et al (2021) which investigated the predicted performance of a thick-wall assembly (533 mm) under future global warming scenarios. Using validated assembly data, the average annual relative humidity levels at the interior face of the exterior sheathing were shown to decrease under all future climate scenarios relative to historical weather data as a result of warmer sheathing temperatures.…”

Impact of Vapor Barrier on Moisture Content of Fiberboard Insulation in Log Structure

“…The influence of vapor barrier equivalent diffuse thickness and the width of an insulation on mold growth risk in log structures was investigated in Alev et al [1]. The paper published by Conroy et al [2] verified the hygrothermal performance of a post and beam building designed to meet the International Passive House Standard both in-situ and via software WUFI ® . Geving et al [3] investigated the moisture conditions in several samples of the wood frame wall insulated with loose-fill and batt wood fiber as well as batt glass wool in variations with wind barrier, vapor barrier, vapor retarder or no barrier.…”

“…Moisture contents of the materials in timber structures under in-situ conditions are described in the paper of Conroy [2]. In the paper, the authors verified hygrothermal performance of a post and beam building designed to meet the International Passive House Standard both in-situ and via WUFI ® software.…”

“…The results are principles for designing log structures, such as appropriate choice of vapor barrier and width of the insulation. Due to different timber structures, verified materials, weather and geographical conditions and the period of verification in the papers of Conroy [2] and Glass [4], these results cannot be compared. Moisture content verifying methods and climate conditions both outdoors and indoors are identical.…”