Thermal resistance of multi-functional panels in cold-climate regions

Abstract

In recent years, energy efficiency and sustainability have garnered widespread attention as buildings account for 30–40% of total primary energy use in North America and 24% of global greenhouse gas emissions. Owing to the cold climate in Canada, energy-efficient building practices have drawn significant interest among authorities and researchers who aim to develop sustainable means of improving energy efficiency. Among these means is the use of environmentally friendly building materials that also contribute to improving thermal resistance. This research investigates and evaluates the long-term thermal performance of innovative multi-functional panels (MFPs) in various wall assembly configurations for residential buildings under varying climatic conditions. The two types of MFPs under investigation combine two layers of wood sheathing with either wood fiber or extruded polystyrene (XPS) as an additional external layer to conventional light wood-frame wall assemblies in order to improve the overall energy efficiency of the conventional wall assemblies. For this purpose, two full-scale identical demonstration buildings (test houses) are built for in-situ testing—one located in the cold continental climate of Edmonton, Canada, and the other in the humid coastal climate of Vancouver, Canada. The two types of MFPs (with wood fiber or XPS) are added to conventional wall assemblies and placed on both north and south façades of each of the test houses. Sensors are installed on each wall assembly under controlled indoor climatic conditions to monitor temperature, moisture content, and heat flux at the inner, middle, and outer layers and at three different vertical levels for each wall assembly. The indoor climatic conditions are maintained by installing a floor heating system, an air conditioner, and a rotating fan for even air circulation. Also, each test house is equipped with a weather station to monitor solar radiation, precipitation, atmospheric pressure, outdoor temperature, and relative humidity, among other metrics such as dew point, wind direction, and wind speed. Results from this study demonstrate the effect of various weather conditions on the thermal performance of MFPs in comparison with conventional wall assemblies and future research will determine the long-term hygrothermal performance of the MFPs under investigation. The ongoing long-term study will provide a practical guideline for the use of wood fiber—an environmentally friendly and recyclable material—as a sustainable insulation material in the North American housing market.