GB 50736-2012 第3.0.7条
| The minimum thermal resistance of the building envelope shall be calculated according to the following formula: R₀·min = (tₙ - tₑ)·Rₙ / Δtₓ, where tₙ is the winter indoor design temperature, tₑ is the winter outdoor design temperature for the building envelope, Rₙ is the internal surface heat transfer resistance of the building envelope, and Δtₓ is the allowable temperature difference between the indoor air and the internal surface of the building envelope.