This Digital Learning Path discusses thermal bridges, which are weak points in building envelopes that allow heat to escape faster than surrounding areas, leading to energy loss, moisture buildup, and mold formation. Thermal bridges can be either constructional, caused by breaks in thermal insulation, or geometric, due to the building's shape. The material explains how to calculate thermal bridges in different dimensions, using coefficients like Ψ to adjust for one-dimensional assumptions. It includes an example of analyzing a balcony slab for thermal issues. Emphasizing the significance of addressing thermal bridges in window frames for energy efficiency, it notes that such bridges can impact up to 25% of a building's heating or cooling needs. The text also warns of humidity problems caused by condensation on cold surfaces, which can promote mold growth. Overall, it highlights the importance of understanding and addressing thermal bridges to optimize building performance.