Thermal comfort for human

Factors that affect human comfort are dry bulb temperature, humidity, air movement, fresh air, clean air, noise level, adequate lighting, proper furniture and work surfaces. However for thermal comfort only consider dry bulb temperature, humidity, and air motion. Therefore the effort to make thermal comfort is how to create those factors are appropriate for the activity level of people in the space.

To make body feel comfortable, the surrounding environmental must be suitable to transfer heat from body to ambient. If surrounding temperature is too high, body feels uncomfortable warm. Moreover if the humidity is also high, it makes body sweating. Also if the temperature is too low, body losses more heat than it produce, and probably it makes body aquiver.

Heat generated by people depends on the people activity. The people who are sitting and doing sport generate different amount of heat. Almost definitely, sport produces more heat than sit. Therefore designing thermal comfort need consider people activity.

For creating environment temperature to be appropriate for the occupancy, cooling or heating system is needed. For example in summer, the temperature is too warm, so air conditioning system (cooling system) is needed. Cooling and heating use heat transfer principle. Those are heat cannot be destroyed, heat flows spontaneously from higher temperature to lower temperature, and heat can be transferred to another substance.

For estimating cooling load and heating load need desired condition. Usually the desired condition is chosen 78^oF (25.6^oC) and 50 % Humidity.  For detailed human thermal comfort, ASHRAE standard 55 Thermal Environmental Conditions for Human Occupancy is made as a standard.