Updated: Aug 4
An explainer about thermal bridges which we are working to eliminate in a passive house.
If you can imagine the heat in your cozy house wanting to make its way outside, and choosing the path of least resistance. A thermal bridge is a pathway. It is likely to be a component of your house that is a heat conductor, such as a steel frame or column, or even an exposed edge of a concrete slab foundation.
Insulation is key to keeping heat in, and window frames are available these days that are thermally-broken, or low conductors.
As shown in this picture, details are also important. External wall membrane and window sealing, done correctly, allows insulation and thermal bridge-free materials and design to do their work.