To provide ventilation, the facility has an air handling unit, with a supply fan and a return fan. Each fan was directly driven by its own motor through a pulley system. The speed of each fan could be controlled by varying the ratio of the drive wheels between the motor and the fan, but this had no effect on the speed of the motor and offered no potential for saving energy.
Recent changes in activity had led to a reduced air demand. A current tenant of the center had previously been engaged in the manufacture of semiconductors, an activity that generates large amounts of heat and a subsequent demand for air circulation. As this activity had ceased, the air handling unit now had more capacity than required.
To save money and reduce the carbon footprint of the building, ABB Drives Alliance partner, APDS, was asked to look at the potential for using low voltage AC drives on the installation.
APDS installed two ABB standard drives for HVAC, a 22 kW drive on the supply fan and a 15 kW drive on the return fan. Running the air handling unit according to demand and taking account of the reduced occupancy, the ABB drives have reduced energy costs by 70 percent, lowering running costs from 180 pounds to just 50 pounds a week. The annual saving of over 6,000 pounds will give a payback time of 16 months. The savings were verified by the customer using the same methods employed by ABB and APDS.
CO2 emissions have been cut by 12 tons per year.