What does HVAC mean? It means; Heating, Ventilation and Air Conditioning. HVAC systems use ventilation air ducts installed throughout a building to supply conditioned air to a room through outlet vents, called diffusers and ducts to move air through return- air grills. HVAC offers the technology of indoor and vehicular environmental comfort. “R” for refrigeration is sometimes added to the field’s abbreviation as HVAC&R. Industry standards are established that take into account the need to provide a healthy indoor environment as well as the need to protect the outdoor environment we live in.