CC WORKSESSION 01292008 - Laserfiche WebLink

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I Destratification Fans: This building improvement measure will reduce energy use and improve the building's efficiency by eliminating air stratification. Temperature gradients, or levels, occur when there is minimal air movement within an enclosed building space. The hot air generated by a building's heating system steadily rises to the ceiling while, conversely, cold air sinks to the floor. The net effect is that the ambient temperature at ceiling level is substantially higher than the temperature at floor level. Destratification fans will be installed in large areas with high ceilings. Units will be equally spaced throughout the rooms per manufacturer's recommendations. The units will operate based on the outdoor air temperature. When the outdoor air temperature drops below 501F, the units will receive a signal through the control system to start. Units will operate continuously as long as the outdoor air stays below 500F. Johnson � 0 Contmlc Demand Based Ventilation: This control strategy is used where a ventilation system is supplying air to an open area. By design codes, these ventilation units are sized for the maximum occupancy of a space, although this rarely occurs, i.e. auditoriums. A carbon dioxide sensor will be mounted in the occupied space or return air duct. Carbon dioxide is an indicator of occupancy load. This allows the outdoor air damper to be controlled based on the actual occupancy level rather than a predetermined minimum. A VFD will be installed on the supply fan motor, and the temperature in the space will vary the speed of the motor based on need. Variable Air Volume (VAV) Box Controls: The existing VAV boxes are controlled by pneumatic thermostats. This system does not allow any night setback or feedback control to the main air handling unit. Currently, the main air handling unit will provide a constant air temperature. If one room requires more heating or cooling, there is no way to automatically change the discharge air temp from the main unit with the current pneumatic system. This causes many of the hot and cold calls within the building. In addition to the control of the existing VAV boxes, the main headquarters of the police station constantly overheats. This space is connected to a VAV box that serves several spaces and is not properly ventilated. This causes the space to overheat and waste energy. By adding a VAV box for this individual space, the proper amount of cooling can be provided to the space. This will allow the system to reset as required in the main air handling unit. Page 10 City of St. Anthony Village Performance Contract Analysis PRORTRIBUTEAND CONFI JOHNSON NOT TO BE REPRODUCED OR DISTRIBUTED WITHOUT JOHNSON CONTROL6 PERMI6510N