Evaluation of the thermal and structural performance of potential energy efficient wall systems for mid-rise wood-frame buildings

• All tested wall systems achieved the minimum recommendation of RSI 3.45 (R-19.6).
• The conventional wall system had the highest vertical load-bearing capacity.
• I-Joist and staggered wall systems achieved less vertical load-bearing capacities.
• I-joist and staggered wall systems can be used as non-load-bearing wall systems.

Approximately 30% of energy use in Canada is consumed in buildings, specifically space heating, which can be reduced by constructing thermally-resistant building envelopes. This study evaluates potential innovative energy-efficient wall systems for mid-rise (four to six storeys) wood-frame buildings in terms of thermal and structural performances. Regarding the thermal resistance performance, four wall systems are developed, installed in a full-scale test house, and examined, along with a baseline wall system, using the field data collected. The selection of the wall systems is based on current practice, structural analysis, pre-fabricability, and energy-efficiency. Several sensors are installed on each wall system to measure temperature, heat flow, and relative humidity. In addition, structural tests are conducted to determine the compressive loading capacity of the tested wall systems for both concentric and eccentric loads, where full-scale panels are constructed and tested in laboratory. As a general finding, all the tested wall systems achieved ASHRAE's minimum assembly R-value recommendation of RSI 3.45, where the I-joist wall system had the highest R-value, while the conventional wall system had the highest load-bearing capacity. This paper recommends I-Joist wall systems for their higher energy efficiency suggesting more future research on efficient end connections to achieve consistent structural performance.