Ventilation case study

Overview

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.

Situation

    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)

 

Solution

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.

Results

  • 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

 

Discussion

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

 

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