 The mean radiant temperature depends on the temperatures and emissivities of the surrounding surfaces as well as the view factor, or the amount of the surface that is “seen” by the object.So the mean radiant temperature experienced by a person in a room with the sunlight streaming in varies based on how much of his/her body is in the sun.In HVAC, air speed is defined as the rate of air movement at a point, without regard to direction.