This document provides a test method for evaluating the physiological impact of protective fabric ensembles and potentially protective clothing ensembles in a series of simulated activities (phases) under defined ambient conditions. This standard test method characterizes the essential properties of fabric assemblies of a representative garment or clothing ensemble for thermo-physiological assessment: — dry thermal insulation; — cooling properties during average metabolic activity and moisture management (dry and wet heat transfer); — drying behaviour. Default measurements are done on fabric samples representing the garment or protective clothing combination. Optionally and in addition to the standard test method, the same testing protocol can be applied to characterise more complex protective clothing ensembles including underwear, air layer and certain design features[1]. In addition, measurements on readymade garments are possible. This test method is intended to be used to measure and describe the behaviour of fabric assemblies of a garment or clothing ensemble in response to a simulated series of activities under controlled laboratory conditions, with the results used to optimize garment combinations and material selection. Furthermore, this document together ISO 18640-2, is intended to be used to describe the thermo-physiological impact of protective clothing but not the risk for heat stress under actual fire conditions. The results of this test can be used as elements of a risk assessment with respect to thermo-physiological load. [1] A study conducted by Empa (Swiss Federal Laboratories for Materials Science and Technology, Switzerland) showed good correlation between results of standard torso tests (without underwear and air layers on fabrics) to tests on fabrics with underwear, tests on fabrics with underwear and air layers and test on readymade garments (with underwear and with or without air layers) of the same material composition. Due to the added thermal insulation values of the additional layers direct comparison of results between different measurement configurations is not possible, however.