Sweating Guarded Hotplate Thermal Resistance Test ISO 11092
topic
The sweating guarded hotplate measures fabric thermal resistance by maintaining a porous electrically heated metal plate at skin-equivalent temperature within a thermally controlled test chamber, calculating resistance to dry heat transfer from the steady-state power required to maintain the plate temperature against the ambient air temperature gradient. The test specimen is laid flat on the plate under standardised airflow and humidity conditions, with a guard ring eliminating edge heat losses to ensure one-dimensional perpendicular heat flow through the specimen. Results are expressed in square metre kelvin per watt and converted to CLO units for clothing applications.
Role
The sweating guarded hotplate is the primary reference method for fabric thermal insulation measurement — its controlled reproducible flat-plate geometry provides the benchmark thermal resistance value against which all other thermal comfort methods are calibrated, and its adoption in ISO 11092 makes it the mandatory measurement basis for thermal insulation claims in cold-weather sportswear, workwear, and protective clothing certification worldwide.