[AIVC, Air infiltration and ventilation glossary, 1992]:a property of an object which determines the direction of heat flow. When the object is placed in thermal contact with another object, heat flows from the higher temperature object to the lower temperature one. It is measured either by an empirical temperature scale based on some convenient property of a material or instrument, such as the Celsius scale, or by a scale of absolute temperature, such as the Kelvin scale.[EN 12792:2003, 353]:measurement of warmth or coldness with respect to an arbitrary zero or to the absolute zero.