Controlling Thermal Bridging as a Value-Added Technique to Enhance Energy Efficient Building Envelopes

Buildings consume 30% to 40% of all primary energy worldwide and are responsible for 50% of total greenhouse gas emissions. Canada has set a target of reducing greenhouse gas emissions by at least 80% by 2050. The aim of this paper is to investigate thermal bridging in four high-efficient buildings, such as those built to LEED standards. Thermal bridging is a major source of heat loss in many buildings, manifesting itself through exterior envelopes, particularly through studs and wall systems. LEED is an evaluation system that rates how sensitive buildings are to the environment, with one of its main objectives being the reduction of greenhouse gases (GHG) emissions through the implementation of highly efficient mechanical systems and the design of durable and efficient exterior wall systems with appropriate insulation. This research investigates and identifies the location of thermal bridging in high-efficiency buildings using non-destructive testing methods such as thermal imaging and THERM simulations. The study involves using infrared thermography to inspect surface temperature variations and detect irregular thermal patterns that correspond to thermal bridging. By collecting record drawings to identify the construction systems used in the external wall compounds, capturing thermal images with high-resolution infrared cameras, and comparing these images with simulation results, the research provides a comprehensive analysis of thermal performance. The findings from this research are significant, particularly in the context of window curtain walls, steel studs, brick shelf angles, timber frames, and roof hatches—all of which were identified as critical areas of concern due to their propensity to thermal bridges. For instance, window curtain walls, with their metal frames and large glass surfaces, showed temperature drops of up to 8°C. Steel studs, which are highly conductive of heat, resulted in temperature drops of up to 5°C, while brick shelf angles showed a temperature drop of 4°C due to heat conduction through the metal. In timber frame structure the building envelope connector showed temperature drops of up to 7°C. Additionally, roof hatches, necessary for rooftop access, were found to cause the most significant temperature drop of 10°C. The findings highlight the significant impact of thermal bridges on overall energy efficiency, emphasizing the need for careful design and construction practices to minimize heat losses. Addressing these thermal bridging issues is crucial for achieving the ambitious GHG reduction targets and enhancing the sustainability of high-performance buildings.