Common clothing area factor estimation equations are inaccurate for highly insulating (I_cl>2 clo) and non-western...

The aim of this study was to evaluate the equations for calculating the clothing area factor (f_cl) used in the standards based on data sets of clothing ensembles, that are meant to provide thermal comfort over a wide range of climatic conditions from hot summer days to extremely cold winter. Over 10 equations for f_cl calculations were selected from the international standards and the literature. At first a theoretical comparison based on a range of insulation values was performed. Then the data sets were used to compare the equations and measurements on real clothing systems. Most of the f_cl calculation equations do give reasonably good results for western type and industrial clothing with basic insulation (I_cl) up to 1.5 clo. Above the I_cl of 2 clo, the error in the calculations based on traditional equations increases considerably and they overestimate f_cl. Some new equations were suggested for modern clothing systems. Oppositely, for non-western clothing (for hot climate), the available equations did give good match only for very light clothing sets and commonly underestimated the real f_cl. For such sets and and fashion clothes their own equations maybe needed, that count for various design aspects, e.g. fit, draping etc.