Thermal comfort is achieved when passengers perceive the air temperature, humidity, air movement, and heat radiation of their surroundings as ideal and would not prefer warmer or colder air or a different humidity level.
Thermal comfort is influenced by:
Personal factors (degree of activity, clothing, journey time)
Spatial factors (radiant temperature, temperature of enclosing surfaces)
Room air parameters (air temperature, air speed, relative humidity)
These factors have complex effects on the heat balance of passengers. Thus all influencing parameters must be considered in order to achieve conditions which will be perceived as comfortable by a majority of passengers.