The article considers a method for optimizing circular ducts for ventilation and air conditioning systems. Universal dependencies are given to determine the diameters of the cross-sections of the air ducts and the air velocities in them that are technically and economically optimal. It is shown that the optimum air velocity in the section of the ventilation network does not depend on the site location relative to the fan of the system. Specific examples of determining the optimum diameters of air ducts and air velocities in them with the use of the dependences obtained are given in the technical and economic sense.
Keywords: Аir duct, aerodynamic calculation, ventilation system, air conditioning system, techno-economic optimization, optimal diameter, optimal air speed, energy saving, energy efficiency, aerodynamic efficiency