Air conditioning, as defined by the American Society of Heating, Refrigerating and Air Conditioning Engineers (ASHRAE), involves the control of temperature, humidity, movement, and quality of air in an enclosed space independent of outside climatic conditions. Industrial applications such as manufacturing, welding, and spray painting require specialized temperature and humidity control to ensure correct operation under the specific environmental conditions. Residential and commercial air-conditioning systems involve a complex combination of temperature and moisture control as well as lighting, noise and vibration reduction, and filtration to provide comfortable indoor environments for humans and equipment.
Unlike evaporative cooling such as that used by hanging wet grass mats over window openings in 19th century India, modern air conditioners use refrigerant chemicals to cool the air. These compounds, usually carbon-based, are pumped through a system of pipes from the unit’s interior to its outdoor coils, and then back again through a heat exchanger. The air being cooled is blown through the cold refrigerant coils by a fan, and the heat transferred to the coils by the blowing air causes the refrigerant to change from a liquid to a gas. The refrigerant is then pumped to the compressor, where it is subjected to high pressure that compresses the molecules together into a hot gaseous state. The heat is transferred to the condenser coils by the fan and the cycle begins again.
The air conditioner is sized to meet the air conditioning load of the house, meaning how much warm and cool air it must move from inside to outside. In a home, this is based on the square footage of the rooms and the number of people and appliances using energy in each room. The air conditioner is sized to deliver enough energy to get the job done without running out of cooling power, or capacity, within an hour under normal operating conditions. This is why air conditioners are rated in tons, as they must provide enough cooling capacity to match the house’s energy consumption.
In addition to cooling, an AC unit can also provide ventilation and dehumidification in the form of a heat pump or ductless mini-split. However, in our SWFL climate these features are not as important since adequate natural ventilation, aided by tighter building envelopes and duct systems, generally satisfies these needs.
The air-conditioning industry is also developing new technologies for heating, ventilating, and air conditioning, often referred to as HVAC. These systems combine all of these functions into a single integrated unit that is controlled by one central computer, and often referred to as a smart thermostat. This technology allows a user to set an exact temperature for every room, and to monitor the system’s performance remotely from a computer or mobile device. Various combinations of these systems are available for different types of buildings, and they can be combined with other systems such as fire sprinklers for added security. This technology is rapidly gaining acceptance as it is able to meet the need for a more efficient, healthier indoor environment.