Ventilation case study


Project Reference274 E
Industry or SectorCommercial Office Building
Energy UseAir-Conditioning (Ventilation)
Date AddedDecember 2005
AbstractInnovative design and use of electronically commutated direct current motors fixed a ventilation and comfort problem for a Melbourne office building, while overcoming electrical supply capacity limitations.


    Original belt-driven centrifugal fan under test

  • A Melbourne office building had unsatisfactory air-conditioning performance
  • Airflow measurements and our analysis showed that 10% more supply air was needed in order to achieve comfort conditions
  • The two existing 40 year old, centrifugal fans on a common shaft, were belt driven
  • Increasing fan speed was not an option because the motors were already overloaded, and the building electrical system was near capacity
  • Therefore, could not “re-pulley” the fan to increase airflow
  • The electrical motor was a standard efficiency unit
  • A belt drive transmitted power from the electrical motor to the fans shaft (Our experience has shown that V-belt drives can have an efficiency of less than 75%, despite much higher figures and rules-of-thumb being commonly published and assumed)



Bank of four new fans to replace old single fanGenesis Now developed a solution with fans supplier Fans Direct, using a bank of 4 high-efficiency fans, electronically commutated, direct current (“DC EC”), variable speed fans.


  • The target 10% increase in air flow was achieved
  • Fan current was reduced by 10%, despite the increase in air flow
  • The new fans are much quieter than the old fans, improving conditions in the building
  • Air distribution across cooling coil has improved significantly, and so cooling performance, has improved



This project illustrates the benefits which can flow from lateral thinking and cumulative improvements in efficiency.


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