What does "thermal bridging" refer to?

Thermal bridging refers to areas within a building's envelope where there is a significant difference in thermal resistance, leading to increased heat transfer. Specifically, this occurs in materials that have high thermal conductivity, allowing heat to flow more easily compared to surrounding insulated areas. This often manifests in points such as structural elements like steel beams or concrete, which can act as pathways for heat to escape, thereby reducing the overall energy efficiency of the building. By understanding thermal bridging, energy raters can identify critical points where insulation might be compromised and implement strategies to mitigate heat loss, improving the building’s performance.