In building envelopes, heat loss through windows is an important contributor. It’s possible to measure the R-value of windows. The R-value describes the effectiveness of insulating material. The higher the R-value, the better the insulation performance of the window. Which sensor model is best suited for testing on windows? Model FHF05-85X85. This sensor is very sensitive and capable of measuring low heat flux levels. It has a low thermal resistance, resulting in a low resistance error. This reduces the uncertainty of corrections. More about window thermal insulation testing can be read in our application note: https://www.hukseflux.com/uploads/inline/note-measurement_of_window_glass_insulation_R-value_with_heat_flux_sensors_v2308.pdf