A concept of the „comfort in clothing” was defined and a visualization scheme was created. The level of the physiological comfort, cooling or potential heat-stroke of the state institution officials in the Republic of Latvia was predicted while wearing everyday functional clothing during its guaranteed usage period. To forecast the physiological comfort, four experimentally functional daily clothing sets of the State Police of Latvia and the State Border Guard were researched and compared. The thermal resistance of the most typical fabrics and their layering of the sets were determined experimentally on the Permetest Sensora equipment, according to the requirements of the LVS EN ISO 11092 standard. To evaluate the results of the experiment and forecast the everyday work clothing performance, standardized calculation methods of ISO 11079, ISO 9920 and ISO 7930 were used. The objective of the research: to forecast the physiological comfort of the officials of the State Police and the State Border Guard wearing functional clothing while performing a specified physical activity in a specified clothing in certain environmental conditions. It was concluded that the physiological comfort was significantly affected by the thermal insulation of the clothing’s fabrics and their layering, which, furthermore, is affected by the percentage relation of the area of a dressed body versus the area of a naked body.