The increasingly stringent energy and emission targets have made thermal bridging a critical consideration for building construction. Thermal bridging is excessive, localized heat flow through discontinuities in the insulation layer, such as at window and door assemblies, building envelope junctions, or balconies, that significantly increases space-heating and cooling demand, depresses interior surface temperatures, and promotes moisture-related durability problems. This paper presents a state-of-the-art critical review of thermal bridging in buildings, with emphasis on its mechanisms, quantification, and mitigation. The classifications, causes, and locations of thermal bridges within the building envelope are synthesized, and methods for evaluating them, including the Equivalent Wall Method (EWM), the Equivalent U-Value Method (EUVM), and 2D/3D numerical modelling, are compared. Element-specific mitigation strategies for openings, exposed structural components, walls, junctions, and balconies are reviewed, highlighting their influence on effective envelope R-values, building energy use, and condensation risk. The literature shows that thermal bridges account for a substantial fraction of heat loss in highly insulated buildings and become proportionally more important as envelope requirements tighten. Key knowledge gaps are identified, including the scarcity of long-term experimental validation and the need for holistic, constructible solutions that integrate structural, architectural, and thermal performance. Practical Application Thermal bridging can materially affect heating and cooling loads, interior surface temperatures, and moisture risk in high-performance envelopes. This review provides building professionals with a comprehensive foundation to identify high-impact details (openings, slab edges, balconies, and junctions), select appropriate quantification methods (Ψ/χ values, EUVM, and 2D/3D modelling) for design and compliance, and prioritize constructible mitigation strategies, such as, but not limited to, continuous insulation, thermally broken connections, and improved detailing and quality control. The review supports a more holistic, durability-focused decision-making process through efficient HVAC system sizing and smart envelope design.
Ahsan et al. (Thu,) studied this question.