Calculate total thermal resistance and U-value from layer thicknesses, conductivities and a surface resistance you enter.
Your input
Outputs are cleared when the input changes.
Result
Enter your data or use the example, then run the tool.
Worked example
A 0.1 m layer with k=0.04 gives R=2.5. Add a user-entered surface R=0.17 for total 2.67 and U≈0.3745.
Method
For each layer, divide thickness in metres by thermal conductivity in W/(m·K) to get thermal resistance R. Add the layers and the entered surface resistance. U-value is 1 divided by total R.
Limits
Assumes heat passes steadily through flat layers in one direction. Material values must be supplied; thermal bridges, leakage and moisture are not included. The result is not a building-compliance or energy-use assessment.
Your inputs stay on this device. Only optional, consented page visits are measured. Input values, files, filenames and processing logs are not sent to Analytics.
When switching languages, text, settings and selected files are temporarily kept on this device. Transfers are removed after restoring; interrupted transfers are cleaned up on a later visit. Inputs and files are never uploaded.