Understanding R-Value and U-Value
R_total = R1 + R2 + R3 + ... (add all layers)
U = 1 / R_total
Heat Loss = U x Area x Delta-T
- R-value measures thermal resistance (higher = better insulation)
- U-value measures thermal conductance (lower = better insulation)
- Always include air film resistances for accurate results
- Outside air film: R-0.17 (winter), Inside: R-0.68 (still air)