 According to ANSI/ASHRAE Standard 55, it is the average speed of the air to which the body is exposed, with respect to location and time.The temporal average is the same as the air temperature, while the spatial average is based on the assumption that the body is exposed to a uniform air speed, according to the SET thermo-physiological model.However, some spaces might provide strongly nonuniform air velocity fields and consequent skin heat losses that cannot be considered uniform.