Heating, ventilation, and air conditioning

This article is about the combined HVAC system. For the heating component, see Central heating. For the ventilation component, see Ventilation (architecture). For the air conditioning component, see Air conditioning.

"Climate control" redirects here. For environmental protection efforts, see Climate change mitigation.

Diagram showing main components of an HVAC system

Rooftop HVAC unit with view of fresh-air intake vent

Ventilation duct with outlet diffuser vent. These are installed throughout a building to move air in or out of rooms. In the middle is a damper to open and close the vent to allow more or less air to enter the space.

The control circuit in a household HVAC installation. The wires connecting to the blue terminal block on the upper-right of the board lead to the thermostat. The fan enclosure is directly behind the board, and the filters can be seen at the top. The safety interlock switch is at the bottom left. In the lower middle is the capacitor.

Heating, ventilation, and air conditioning (HVAC /ˈeɪtʃˌvæk/) systems regulate temperature, humidity, and indoor air quality in vehicles and buildings. They are designed to provide thermal comfort and to control airborne contaminants through heating, cooling, ventilation, filtration, and humidity control. HVAC design considerations include energy efficiency, indoor air quality, maintenance, and environmental impact, particularly in green building projects. In building design, mechanical, electrical, and plumbing engineers may integrate HVAC systems with other building systems (i.e. air-source heat pump water heaters) and use energy modeling to evaluate performance and operating costs.