Heating, ventilation and air conditioning (HVAC) is the technology of indoor and vehicular environmental comfort. Its goal is to provide thermal comfort and acceptable indoor air quality.
Ventilation includes both the exchange of air to the outside as well as circulation of air within the building / compartment. Methods for ventilating a building may be divided into mechanical/forced and natural types.
Heaters are appliances whose purpose is to generate heat (i.e. warmth) for the building / compartment. This can be done via central heating. The heat can be transferred by convection, conduction, or radiation.