Theory 37/Building Physics
Thermal Bridging Is an Area Ratio
The claim
Heat loss through thermal bridges is set by the ratio of bridge area to envelope area, so a small poorly insulated detail can dominate a well-insulated envelope.
01Mechanism
Bridges bypass insulation; their contribution scales with how much of the envelope they occupy relative to the insulated area.
02Predictions
- P1Loss should track the area ratio.
- P2U-value alone should mispredict.
03Refutation
Loss tracking U-value would remove the bridge area.