Thermal bridging (sometimes called cold bridging) happens when an insulation layer is breached by a material with higher conductivity, or the thickness of the insulation is not sufficiently continuous. Thermal bridging is an important source of thermal discomfort, moisture problems and underperformance in low-energy buildings. Designing buildings to be as free from thermal bridges as possible is important for meeting UK building regulations and essential to meeting Passivhaus standard. I am trained in thermal bridge calculations using THERM in order to assess the expected impact of any thermal bridges in a design.