# U-value for 127mm air gap?

do you know where i can refer the u values for air gap?

Do you know what is the u calue for 127mm air gap

• Thermal conductivity for air varies based upon its temperature. It is usually listed as about 0.025 which is in watts per meter per degree C. So I believe the conductivity for 127 mm would just be 0.127 x 0.025.

You will need to crunch the numbers to get the units you need.

However, U value is based upon conduction; with air there will also be convection, since it is not a rigid insulator.