Some of the researches expressed connection between the numbers and size of the microclimatic air layers on thermal insulation of clothing. The insulation of the ensembles is much affected by the air enclosed between the clothing layers. In loose fitting clothing, they are less subjected to compression and thus add more to the overall thermal insulation. The heat and the moisture are released from the body into the microclimatic layers, subsequently changing properties of the entrapped air. The volume of the microclimatic air layers was investigated by the use of non-contact 3D CAD method. The temperature and humidity changes of microclimatic layers were also observed. This paper represents layer by layer quantification of the clothing ensemble volume with jackets as covering garment and the impact of the microclimatic volume on the clothing insulation. The three-level laboratory testing was performed with human subjects dressed in selected ensembles.