Fans are an essential part of air conditioning and ventilation systems. However, they also account for a significant proportion of the energy consumed. In cases where new air conditioning and ventilation systems are not yet available, it is important to retrofit existing system with fans that have the highest possible performance standards.

Centrifugal fans are commonly used in air handling units (AHUs), while axial fans are often seen in air-cooled condensers and dry coolers. In both cases, fan efficiency can be optimised, thanks to a series of technological improvements.

For example, one way to improve fan efficiency in AHUs is to replace belt-driven forward curved fans with backward curved ones. Even better, replacing the belt-driven systems with direct-driven ones can result in efficiency gains of up to 15 percent; maintenance costs and system contamination can also be significantly reduced because there is no belt-dust generated. Finally, electronic commutation (EC) technology can be utilised for speed control. The highest efficiencies are achieved by matching high-efficiency backward curved impellers wit high-efficiency EC motors.

On the other hand, in some air-cooled condensers and dry coolers, there may be as many as 16 axial fans. Therefore, a small energy saving per fan can result in significant saving per condenser or cooler. In order to achieve the highest combined efficiency, the EC motors with the highest electrical efficiencies must be matched to the axial impellers with maximum aerodynamic performance. Advanced blade designs, some incorporating serrated trailing blade edges, further help reduce the levels of emitted noise.