Final Results

Although this new strategy was implemented in late January, it has already shown a noticeable reduction in chiller energy consumption. Figure 1 shows the monthly average chiller consumption for days with maximum temperatures of less than 20°C (68°F), between 20°C and 24°C (75°F), between 24°C and 30°C (86°F) and days over 30°C. The consumption between 24°C and 30°C (purple) was fairly steady from October; then a drop occurred in January as there were 10 days of the month with the new strategy operating. A significant drop occurred in February for both temperature ranges as this is was the first full month of the new strategy operation; consumption for days between 24°C and 30°C reduced by 99% and days over 30°C by 78%. This is a dramatic drop in energy consumption and equates to a total reduction of over 70% on total chiller energy consumption.

The Benefits

The effects of poor air handling unit control can have significant implications on the thermal plant energy consumption. It is extremely important that all pieces of equipment work together and do not fight one another to achieve the most efficient system operation. The new economy cycle control strategy has the potential to save in excess of 300,000 kWh per year without a negative impact on occupant comfort.