HVAC (Heating, Ventilation, and Air Conditioning) must be a hepa filter system. This is designed to keep the air as clean as possible, and reduce unwanted particles from floating about in the air. There must be a professional to decide how powerful of a system is required, as well as defining the diameter of the lines going to the rooms. There must be pathways to make as few 90° turns as possible. This is for system efficiency.