J. Drenda

Determination of Climatic Work Conditions—Thermal Discomfort Index

Climatic conditions in underground mines and other plants depend on climate, kind and intensity of work (metabolic rate), clothing and acclimatization. The thermal discomfort index “δ” is the parameter which evaluates these conditions. The paper presents its definition and tables including metabolic ratios and thermal insulation of miners’ clothing determined from in situ measurements. The nomograms specified for estimation of the index have also been presented in the paper. Five nomograms are included in the text concerning different values of relative humidity: 20, 40, 60, 80 and 100%. Each nomogram includes the results for a non-clothed man (thermal insulation of clothes Icl = 0) and for a fully-clothed man (Icl = 1 clo). The nomograms also consist of isolines of air velocity and metabolic rate for workers who are acclimated and for those who are not acclimated. Results for different values of relative humidity can be interpolated. The value of “δ” does not have a unit. When δ = 0, it is understood as thermal comfort; when δ ≥ 1, it is understood as a dangerous discomfort. However, when 0 < δ < 1, the value denotes acceptable discomfort conditions.