Subject : Refrigeration and Air Conditioning

Topic : Air Conditioning

Difficulty : Medium

According to ASHRAE, ‘Human comfort is that condition of mind, which expresses satisfaction with the thermal environment’.

Thermal comfort refers to the subjective feeling of temperature in an environment. Optimum levels of thermal comfort helps in maximizing productivity Temperature, humidity, purity and motion of air are the important factors which affect the human comfort. The system which effectively controls these conditions to produce the desired effects upon the occupants of space is known as an air conditioning system.

In comfort air conditioning, air is brought to required DBT and relative humidity for human health, comfort and efficiency. If sufficient data on required conditions is not available then DBT is assumed as 21°C and relative humidity as 50%.

The sensible heat factor is generally kept as follows: For residence or private office=0.9 For restaurant=0.8 Auditorium or theatre=0.7 Dance hall or gym=0.6