What are HVAC Systems?

The air conditioning system reduces the indoor air in summer and increases the indoor air temperature in winter. This process is accompanied by air humidity, cleanliness control and wind speed adjustment. Refrigeration technology is the basis for this process. Refrigeration technology is one of the inventions that changed human life. It can use energy to transfer heat from low-temperature objects to high-temperature objects. Generally, a system that cools in summer is called an air conditioner; if the system can also heat in winter, it is called a heat pump. ^[1]

Domestic air-conditioning systems are small in scale, and use refrigerants to directly cool (heat) the air. Generally, no air duct is provided to transmit air. ^[1]

The difference between a heating system and a central air-conditioning system is that the heat in the hot water or steam is radiated to the room through a radiator, instead of exchanging air through the central air-conditioning system. The main heat source of a heating system is a boiler, and the scale of central heating ranges from a building to an urban area or even the entire city. Because heating in severe cold areas is a necessary condition for people's lives, heating in China accounts for a large proportion of building energy consumption. ^[1]

Ventilation in a broad sense includes air conditioning. Ventilation in a narrow sense can be understood as the exchange of indoor and outdoor air without heat and heat exchange. When the temperature and cleanliness of the outdoor air are appropriate, only the ventilation can also adjust the indoor environment to an acceptable level, which saves a lot of energy compared to heating and air conditioning. ^[1]