People sweat to release excess heat while doing exercises and the microenvironment under clothing will be in a hot and wet state. Ventilation which is caused by air movement is an effective way to dissipate heat and moisture, and thus keep a comfort clothing microenvironment. There are two approaches for clothing ventilation design: to choose proper fabric materials of superior air and vapor permeability, and to use special vent design or include mesh fabric on some particular body parts. To investigate the effect of ventilation design on sportswear microenvironment, four T-shirts made of different fabric materials were chosen for study. The air permeability and water vapor permeability of the materials were measured. Wear trials under a certain exercise condition were conducted in an environment of constant temperature and humidity, the volunteers' skin temperature and the temperature and relative humidity of the microclimate under the T-shirts were recorded. By linking the fabric materials properties with wear trials' results, it was clear that the water vapor permeability has direct influence on the humidity of clothing microenvironment, and when the air permeability is high enough, the ventilation through fabric will enhance heat and moisture dissipation and thus reduce the temperature and humidity in microenvironment.
