Overview.

Project No.	274-E
Industry or Sector	Commercial Office Building
Energy Use	Air-Conditioning (Ventilation)
Date Added	December 2005
Abstract	Innovative 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

• 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:

Genesis 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 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.