India Cooling Action Plan recommends that the temperature setting of the Air conditioner has to be at 24^oC and this is discussed at length in many forums. Many a time we hear of the 1 degree challenge and we (ISHRAE members) have even taken oath (during an NBoG) that the setting should be at 27^oC.  Everyone is aware that this is to reduce the energy input required for cooling. At the same time it is understood that the main aim of an air conditioner is to keep the human in a state of thermal comfort.

Humans are heat engines. The human body constantly generates heat as a byproduct of metabolic processes. This heat needs to be regulated to maintain the body's core temperature within a relatively narrow range for optimal physiological function. A human body loses heat primarily through four mechanisms: radiation, conduction, convection, and evaporation

The surface area of an average human body is 1.5 to 2.0sq.m.  The normal body temperature (as measured by a clinical thermometer ) is around 37^oC but the skin is at an average temperature of 33^oC. The body has to reject heat to the surroundings but the clothing we wear provides insulation, following Q= U A ?T,  if U is low then ?T has to be high for same Q to happen.

The insulation due to clothing is termed as the ‘clo’value where 1 clo = 0.155 K·m²·W⁻¹ 

The higher the clo value, more is the insulation due to clothing.  Eg. See some representative values in the table below

As can be seen, the common so called ‘formal wear’ has a higher insulation effect.  

Coming back to the heat loss mechanism of sweating and its evaporation, it is just common sense that the clothing unless it is absorbent and brings out the sweat by capillary action like in a fabric like cotton, it will not serve its function.  The relative humidity of the surrounding air also needs to be low for moisture transfer to take place.

It is commonly believed that the jacket and tie is the ‘business wear’ but one can see that it is counterproductive in our quest for energy efficiency.  Our Middle Eastern friends do business in their traditional wear so why not we Indians too?

In closing it is really heartening to see these lines from the notification for an ASHRAE event in September “We therefore request you to dress up accordingly and wear smart casuals made out of Cotton only. No Jacket or tie is required for any of the events.”