Central air conditioning is a method of structural cooling in which a centralized unit cools and dehumidifies air before circulating it throughout a building. This is in direct contrast with systems that rely on individual units in rooms or suites of rooms. Central air, as it is also known, is often bundled with a heating system, as both rely on similar amounts of electrical power and ductwork to distribute cooled or heated air. This type of air conditioning is generally seen in large structures, or in homes in extremely hot, humid climates.
With central air, the main unit is often located outdoors or in an isolated area of a building because a great deal of noise is generated during the refrigeration cycles that cool the air and help to extract humidity. The unit connects to ductwork that runs throughout the building, with blowers pushing cold air out of the ducts to cool down rooms. The air conditioner also vents to the outdoors to get rid of excess heat and moisture.
Ductless air conditioning can also be used to cool air in large areas, but instead of relying on ductwork, it uses individual wall units that pull out moisture and hot air, and pump in cool air. This form of air conditioning can be more environmentally friendly, as people can control the climate in individual rooms or groups of rooms, rather than using a single central unit to maintain a desired temperature. Because temperatures can vary considerably across a structure, central air conditioning can use a lot of energy in its attempt to keep the air comfortable.
For large buildings, central air conditioning is critical, because the air can grow quite oppressive, especially in warm weather. Heat from the weather can make the building warm up, as can the heat from the bodies in the building, and moisture also accumulates as a result of respiration. Using central air will keep a building comfortable for people to work in and make it more pleasant for visitors who may be entering the building, such as customers entering a department store.
Homes in hot climates may also benefit from central air. Using this type of air conditioning system eliminates the need for wall or window units, which are often unsightly and can be difficult to manage. Central air, much like central heat, can also be calibrated to keep temperatures within a stable range while retaining energy efficiency. This is especially true when central air or heat is combined with measures such as insulating a home to help it resist external temperature changes and designing a home that is suited for its climate.