Air-conditioning for comfort has to provide a healthier atmospheric conditions. As atmosphere is a function of temperature, air motion or velocity and humidity, the principles of air-conditioning should involve the proper control of these parameters.
1. Temperature Control
The range of temperature which is suitable to majority of people is called the comfortable zone. The comfortable zones are different for summer and winter seasons due to changes in body conditions and the clothing of human beings. The effective comfortable zones for summer and winter range between 20–23°C and 18–22°C, respectively. This effective temperature range is the measure of comfort of human body under most conditions of humidity and air motion. Irrespective of the outside temperature, a temperature range of 21–22.5°C is required for comfort conditions.
2. Air Motion Control
Air motion or velocity is another important factor as an increase in velocity of air results in decrease of inside effective temperature much below the outside temperature. This change in turn upsets the regulation of conditioned air. The air is considered as still air when the velocity of air is in the range of 6–9 m/s.
3. Humidity Control
In order to condition the air, the control of humidity is very important. Passage of dry air through nasal membranes irritates to a great extent. Because of this moisture is added to the heated air (i.e., humidification) or extracted (i.e., dehumidification) depending on the necessity. During summer a humidity of 40–50% and during winter 50–60% are the best. On an average, the value of relative humidity between 40 and 60% is considered desirable.
Leave a Reply