This study is aimed at using clo values for individual garments and some sort of combination formula to estimate the clo value for a complete ensemble. Although the number of significantly different garments is large, it is a manageable number thus making it reasonable to tabulate clo values for most garments of interest. From this finite collection of garment data, a very large number of practical ensembles can be assembled and their clo values estimated by a combination formula. This approach greatly reduces the burden of collecting basic data. Furthermore, it will be possible to survey the occupants of a given space, determine what garment combinations they are wearing, and from this determine an appropriate clo value factor for the space.Presented in this paper are area factors and clo values for representative garments and ensembles plus some simple formulas for estimating ensemble area factors and clo values from corresponding garment data.