It is a property of textile materials that creates ease by maintaining moisture and thermal levels in a human's resting and active states.
While it is possible to determine the increase of insulation provided by chairs, sleeping or resting situations are more difficult to evaluate unless the individual is completely immobile.
Accurate estimates of clothing insulation for an active person are therefore not available, unless measurements are made for the specific condition (e.g., with a walking manikin).
Recent studies have developed dynamic predictive clothing insulation models that allow more precise thermal comfort calculation, energy simulation, HVAC sizing and building operation than previous practice.
A model that is able to predict how building occupants change their clothing would greatly improve HVAC system operation.
Moreover, clothing variability may also depend on factors unrelated to thermal conditions, such as for a dress code or social influences, style preferences that may differ due to gender or work position.
According to ASHRAE-55 standard, only if individuals are freely making adjustments in clothing to suit their thermal preferences, it is acceptable to use a single representative average value for everyone.
[1] Some basic insulation values can be considered as examples of typical conditions[13] The ambient temperature at which someone's body will be at thermal equilibrium depends on the rate of heat generation per unit area P and the thermal insulance of the clothing R. The empirical formula is:[citation needed] or, if R is taken to be the number of clos and P the number of watts per square metre,