HVAC is a sequence of technologies often used for room temperature, humidity & ventilation management within a given region. It is designed to provide a comfort level and an acceptable standard of indoor air to be used. The design of HVAC systems is the subject of mechanical engineering. HVAC is implemented based on thermodynamics, heat transfer & fluid mechanics principles. HVAC systems can be used for residential as well as industrial properties. It requires a central system for air conditioning, heating & ventilation.