Air conditioning (also known as AC or ac) is the process of removing heat from an environment and maintaining a comfortable temperature and humidity. Its main use is for human comfort, but it can also be used in industrial applications to control the working conditions of equipment or processes that require specific environmental conditions for proper operation or to perform their work.
Before air conditioning, mechanical cooling was accomplished by storing ice in large blocks. These were moved indoors during the night and removed during the day to keep buildings cool. This method had its problems, including high operating costs and the need to keep large ice blocks on hand. The development of the first mechanical refrigeration systems allowed for a better and more reliable way to cool buildings.
The invention of the electric motor and its application to fan and compressor technology made it possible to cool buildings using a centralized system. These early air conditioning systems were usually referred to as process or industrial air conditioning, but the advent of Willis Carrier brought an engineering, scientific and business approach to air conditioning that greatly expanded its application to personal comfort as well. Carrier is considered the father of modern air conditioning and is credited with several inventions that are still in use today, including dewpoint control, the psychrometric chart, and the principle of the refrigerant cycle.
Today’s air conditioning is a complex and highly efficient system that uses a combination of mechanical refrigeration, electrical heating, and computer control. The basic components of most modern air conditioning units are a blower that moves cooled air over an evaporator coil, where it evaporates, or changes from liquid to gas. The evaporated air is then blown out through another coil, called the condenser, where it cools down and returns to its liquid form. The cooled air is then blown back into the building through the distribution ducts.
A new development in air conditioning involves the use of thermal storage to reduce energy needs. Some systems are designed to “store” cooling during the night when energy prices are lower, and then release it during the day. Other innovative approaches to energy management include shading and “low e” glass to reduce solar heat gain, and ventilation systems that recycle stale air with outside fresh air.
The future of air conditioning appears to be centered on intelligent building systems that can respond in real time to changing environmental and occupancy conditions. The concept is to create a building environment that mimics the natural climate of the surrounding area as closely as possible. This will require precise and sophisticated control of four fundamental variables: air temperature, humidity, movement, and quality. These controls will be able to interact with each other to provide the best possible condition for human psychophysiological comfort and performance. They will also interact with other systems in the building, such as fire detection and fire suppression, lighting, and transportation. The end result will be a “building brain” that responds to its environment to provide the best possible comfort and productivity for its inhabitants.