Thermal Bridging in Windows: A Critical Review on Mitigation Strategies for Enhanced Building Energy Efficiency

Abstract

Thermal bridging in windows presents a significant challenge for building energy efficiency, particularly at window-wall junctions where material transitions cause heat loss. As energy standards become more stringent, minimising these heat loss pathways is essential for achieving sustainable design objectives. Thermal bridges increase energy consumption, diminish insulation effectiveness, and compromise overall building performance. This review explores the impact of thermal bridges in windows and glazed areas, highlighting advancements such as thin-film photovoltaic (PV) glazing, vacuum glazing, aerogel glazing, low-e coated multilayer systems, transparent insulation materials (TIM), and phase change materials (PCM). It also evaluates high-performance window frame materials, such as fibreglass and composites, alongside advanced installation techniques like thermal breaks and insulation barriers at window-wall interfaces, for their ability to reduce thermal conductivity and heat transfer. Research indicates that thermal bridges increase building energy consumption by 5%-30%. Cutting-edge technologies, such as vacuum glazing with U values as low as 0.2 W/(m² ·K) and aerogel-filled frame cavities that reduce thermal permeability by 45%, demonstrate considerable energy-saving potential. Furthermore, precise installation techniques lower linear thermal transmittance (LTT) by up to 80%. A holistic approach that integrates advanced glazing technologies, optimised frame materials, and meticulous installation methods offers a powerful solution for enhancing window thermal efficiency, making a substantial contribution to the sustainable transformation of the built environment.