caused cold air to flow through the boxes even when they were in the heating mode, resulting in simultaneous heating and cooling. Furthermore some of the reheat valves were malfunctioning. This caused the reheat to remain on continuously in some cases.

• Additional problems identified from the field survey included the following: 1) high air resistance from the filters and coils, 2) errors in a temperature sensor and static pressure sensor, 3) high static pressure setpoints in AHU1 and AHU2.

This combination of equipment failure compounded by control changes that returned several pumps and fans to constant speed operation had the consequence of increasing chilled water use by 18,894 MMBtu and hot water use by 9,510 MMBtu. This amounted to an increase of 71% in chilled water use and more than doubled hot water use from two years earlier

These problems have now been corrected and building performance has returned to previously low levels as illustrated by the data for April-June 2002 in Figure 26.4. These data are all below the lower of the two regression lines and is comparable to the level achieved after additional CC measures were implemented in 1998-99.

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