Calculate heat transfer rate through a barrier from area, temperature difference and U-value.
Heat flow is proportional to area, temperature difference and the U-value. Since U is the reciprocal of thermal resistance, halving U halves the heat loss for the same conditions. Building regulations specify maximum U-values precisely because this equation makes heat loss directly proportional to them.
Heat Transfer
Q̇ = U A ΔT
Q̇ = U A ΔT Heat flow is proportional to area, temperature difference and the U-value. Since U is the reciprocal of thermal resistance, halving U halves the heat loss for the same conditions.
Building regulations specify maximum U-values precisely because this equation makes heat loss directly proportional to them.
This calculator takes 4 inputs: Surface area, Overall heat transfer coefficient, Temperature difference, Hours per day. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.