OR-25-C012 - Improving Thermal Performance of Prefabricated Wall Systems by Minimizing Thermal Bridging of Steel Brackets and Connectors with Minimal Investment Cost ✓ Most Recent

Prefabricated buildings are gaining popularity worldwide, driven by technological advancements and the demand for sustainable, energy-efficient construction. Thermal bridging through framing and brackets accounts for significant energy loss in building wall systems, contributing up to 30% of the total energy loss, significantly impacting the overall thermal performance of building wall systems. Traditional steel brackets are major contributors to thermal bridging in prefabricated wall systems. Instead of minimizing the thermal bridging to meet the minimum ASHRAE thermal performance requirements in the eight U.S. climate zones, manufacturers and contractors often tend to increase cavity insulation to maintain the ASHRAE standard requirements for the thermal performance of building wall systems. However, this approach is costly. Therefore, the goal of this study is to improve the thermal performance of prefabricated building wall systems by reducing the thermal bridging impact of steel brackets without additional cavity or exterior insulation. To achieve this goal, this study modeled a typical prefabricated wall panel system with L-shape galvanized steel brackets using Multiphysics simulation tool and compared its thermal performance with a newly developed stainless-steel wiring system that replaces the steel brackets at extreme hot climate condition. The simulation results indicated that the newly developed wiring system provided a more uniform temperature distribution across the prefabricated wall panel with temperature varying within 1.8 ? (1 ?) all over the wall panel system. In contrast, the traditional prefabricated wall panel system with galvanized steel brackets exhibited significant temperature variations of about 16.2 °F (9 °C) around the steel brackets, studs, and cavity insulation, indicating considerable thermal bridging. Additionally, the simulation results indicated that the thermal performance (R-value) of the prefabricated wall panel design with the newly developed wiring system outperformed the traditional prefabricated wall panel design with L-shape galvanized steel brackets by about 20% (i.e., R-2.4). This improvement is equivalent to adding half an inch of insulation to the prefabricated wall panel system with the steel brackets. This modification significantly reduces the need for additional insulation material and installation costs, as well as the CO2 emissions associated with additional insulation.