Home Insulation Savings Calculator

U-value and comfort

U-value (W/m²·K) is the inverse of R-value: it measures how quickly heat moves through walls and windows. High U means more heat loss in winter and more heat gain in summer—your HVAC runs longer and rooms feel drafty near exterior surfaces. Better insulation and Low-E glazing lower the composite U of the envelope, shrinking both heating and cooling bills while evening out indoor temperatures.