The HVAC design engineer works with systems of external and internal water supply, sewerage and heating, fire extinguishing, smoke removal, underfloor heating, ventilation and air conditioning of residential, public and industrial buildings, and also designs boiler rooms. HVAC engineering services are quite variable. The listed areas can either be combined in the duties of one specialist, or they can be divided (for example, an engineer can work only with water supply and sewerage or only with ventilation). The design engineer begins his work with a survey of the structure and drawing up a technical assignment, which is approved with the customer. He also draws up and approves an estimate, which takes into account the cost of research and installation work, equipment and materials.