Comparison and correction on calculation methods of clothing insulation based on thermal comfort

Abstract

Clothing insulation is a major factor affecting human thermal comfort, and it is usually a fixed value when the clothing ensemble are determined in the standard. However, real clothing insulation is considerably affected by the environment and activity level (metabolic rate). Thus, the heat flow method for obtaining clothing insulation through thermal equilibrium between the skin layer and environment was proposed. Later, a non-contact method for easy acquisition of clothing insulation was proposed. The method was implemented via infrared imager. In this paper, above methods were compared and analysed based on experiment data. Three activity levels were considered, sedentary (1.0 met), walking at speed of 0.8 m/s (1.8 met), and 1.2 m/s (2.6 met). The feasibility and accuracy of above methods are discussed by comparing the PMV calculated by the clothing insulation with the actual thermal sensation (TSV) of the subjects obtained by questionnaire. The results showed that the non-contact method exhibited the highest prediction accuracy. Due to the sweating effect on skin temperature, the higher the activity levels, the lower the prediction accuracy. In this paper, a correction method of clothing insulation was proposed by using the temperature of face and neck and skin wettedness. After correction, the root means square error between the PMV and TSV decreased by 11 %.