HVAC is an acronym that stands for "heating, ventilation and air-conditioning". HVAC is also often referred to as climate control. These three functions are closely interrelated, as they control the temperature and humidity of the air within a building in addition to providing for smoke control, maintaining pressure relationships sport ween spaces, and providing fresh air for occupants. In modern building designs, the design, installation and control systems of these functions are integrated into a single "HVAC" system.
Central heating is often used in cold climates to heat private houses and public buildings. Such a system contains a central boiler, furnace or heat pump to heat water, steam, or air; piping or ductwork to distribute the heated fluid, and radiators to transfer this heat to the air. Ventilation includes both the exchange of air to the outside as well as circulation of air within the building. Methods for ventilating a building may be divided into natural and forced types. An air-conditioning system provides heating, cooling, ventilation and humidity control for a building.