Evaluation of Energy Efficient Wall Systems for Mid-Rise Wood Frame Buildings
PhD Students: Hamid Zaman, Hadia Awad, Tanzia Sharmin
Researchers: Ahmad Alrifai, Gurjeet Singh
Time Period: January 2012 onwards
This project was part of Value to Wood program funded by Natural Resources Canada
Guidance, support and expert technical advice was provided by NEWBUILDs
Background: The goal of NSERC strategic research network, NEWBuildS, which was established in 2009, is to advance scientific knowledge and construction technologies that will enable wood-based products to be used in mid-rise and non-residential construction, or integrated into hybridized construction. When the program was developed, research on thermal performance of buildings was not included, as energy efficiency was not a high priority at that time. However, in the past few years, the society and the building industry have dramatically changed their view of environmental sustainability. Global warming and greenhouse gas emissions became a major concern. A number of provincial governments (e.g. Nova Scotia, Ontario and British Columbia) have implemented explicit energy performance targets for new buildings within their jurisdictions. The 2011 National Energy Code of Canada for Buildings (NECB) set minimum energy performance requirements for the design and construction of new buildings, as well as substantial renovation in existing ones. NECB does not apply to farm buildings or to buildings covered in Part 9 of the National Building Code of Canada (NBC). The development of energy efficiency provision for housing and small buildings is in progress, and the final results are expected to be published in late 2012 as revisions to Part 9 of the 2010 NBC. To embrace the changes, in 2011, the University of Alberta, in liaise with NEWBuildS, initiated a research project on the evaluation of energy efficient wall systems for mid-rise wood frame buildings.
Summary: This project aims to evaluate the hygrothermal and structural performance of potential energy efficient wall systems for mid-rise wood frame buildings. Four different wall systems are selected based on a number of considerations, such as current practice, preliminary structural analysis, prefabricatability, material availability, and expected energy performance. These four different wall systems (two I-Joist wall systems, two staggered wall systems), along with a baseline wall system (conventional), are then tested using sensors in field conditions. Sensor data is analyzed in order to determine the best wall system from those selected. The selected wall systems are also analyzed for their hygrothermal performance by simulating conditions with WUFI software. Since the wall systems' structural performance is also a major area of concern, efforts have been made to test these wall systems in the laboratory. The results of the structural tests will substantiate the preliminary structural analysis based upon which the wall systems had been initially selected.
A testing house is assembled using the selected five wall systems, placed side by side along one side of the house, to test their hygrothermal performance in field conditions. The side of the testing house comprising selected wall systems is oriented towards the east direction. The indoor dimensions of the house are: length 19 feet 7/16 inches, width 7 feet 10 ½ inches and height 8 feet. There are also two openings in the house (door and window).
Three-dimensional model of the testing house
Types of wall systems selected for testing
Layout of the testing house, showing the location of wall systems
Location of sensors in a wall system
The testing house at site (picture dated: January 2013)