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FY10 RCx (Completed)
The Fiscal Year 2010 Retrocommissioning efforts completed seven more buildings. This year, the Student Sustainability Committee also contributed to funding the RCx efforts for the Illini Union Bookstore.
The 21 air handling units (AHUs) providing air conditioning were maintaining space conditions 24/7/365. The primary energy conservation method was scheduling 10 of the AHUs serving the areas to shut completely off for 6 or more hours a day. The remaining units were scheduled to reduce airflows during unoccupied hours. Eight of the 50+ exhaust fans were found to be unnecessary, even though they were exhausting 24/7 from the premises. RCx assisted in shutting these fans off and abandoning them in place. Various other exhaust fans serving restroom areas were brought over to DDC control and scheduled to operate when building was occupied. To maintain comfort conditions, reheat coil control valves were checked for leakage rates. Reheat valves were replaced as required. Various VAV controllers were found non-operational and were replaced, restoring thermal comfort and improving minimum air flow control.
Coordinated Science Lab
Upon arriving at the building, many complaints about indoor air quality and cooling problems were communicated. Many occupants also noted that their thermostat did not control, or did not know where their thermostat was or who they shared with. Due to balancing problems, many occupants had placed varying objects in the grilles to reduce air flow in their space. RCx visited each of the 277 VAVs and re-balanced each space for improved airflow while removing the accumulated “air blockers”. The fanpowered VAVs were also re-balanced to deliver all conditioned air to the space and allow for return air from the plenum for tempering as required. IAQ issues were resolved due to these time intensive efforts. Air being delivered to Liebert controlled spaces was removed with the goal of improving humidity conditions, reducing needless reheating, and eliminate any “fighting” between the units. A couple of special larger projects were recommended to improve energy avoidance in these spaces.
Illini Union Bookstore
The air handling units (AHUs) providing air conditioning were maintaining space conditions 24/7/365. One of the primary energy conservation method was scheduling the AHUs serving the office areas to shut down for 10 to 12 hours a day. Another measure was addressing the issues with the two 150 ton electric air cooled chillers. Both were found running 24/7 at 50%. By expanding the economizer period using enthalpy conditions, filling the water system and raising the temperature for chillers to operate to 53.5ºF, the second chiller can be shut down the majority of the year. To improve comfort conditions, the entire third and fourth floors were rebalanced to deliver proper quantities of air conditioning to the spaces. One predicament that was overcome was the lack of available static pressure on an AHU, and thus VAVs were not able to control. Three VAVs serving non-office spaces were isolated allowing the static to climb enough for VAVs to function. Outside air and economizer control was also improved for one AHU of the building by replacing the outdoor air dampers.
National Center for Supercomputing Applications
The air handling units (AHUs) providing air conditioning were maintaining space conditions 24/7/365, with a setback sequence in place. The primary energy conservation method was connecting the existing occupancy sensors to the VAV box to condition the space only when occupied. Since 90% or better have a 8am to 5pm schedule, large quantities of energy use was avoided. Independent CRUs were monitored to guarantee satisfactory data cluster temperatures. To maintain comfort conditions, the VAV / perimeter heat sequence was reviewed. The radiation was not operating unless the reheat could not satisfy the space. This led to drafty offices. The sequence was rewritten to allow the perimeter radiation to operate independently of the reheat valve, thereby allowing the space to warm even if the VAV box was closed. Unoccupied setbacks were limited to a 10 degree deadband centered on the room setpoint.
The air handling units (AHUs) providing air conditioning were maintaining space conditions 24/7/365. The primary energy conservation method was scheduling the AHUs serving the office areas to shut down for 10 to 12 hours a day and some on the weekends. This was possible due to the perimeter radiation on the exterior offices. Building occupants complained about the faulty readings on the thermostats. Upon RCx investigation of the stats, it was noted that many of the thermostats were out of calibration, if they worked at all! Therefore, the team did a room by room visit and re-calibrated or replaced bad thermostats, as well as providing information to occupants on how to use the thermostat properly and efficiently. Dampers and actuators were repaired and the outside air was reduced in many of the units. The reduction in excess OA quantities will significantly lower the buildings chilled water and steam use, as less completely unconditioned air will be passing over the coils, requiring less energy to achieve the same comfort levels.
Siebel Center for Computer Science
The primary energy conservation method was revisiting the programming of the individual VAV boxes. The program frequently allowed for a 0.1, 0.5 or 0.9 deg F deadband between heating the room and cooling the room. Therefore, it was noted that each room controls were “fighting” each, heating and then cooling immediately. Another major issue found in the programming was found in the setback schedule. The intended setback range of temperatures became the setpoints. The result were rooms in winter cooling the space down to 60 deg F, then warming it up to 72 deg F, then returning to 60 deg F. To maintain comfort conditions, reheat coil control valves were checked for leakage rates. The entire reheat system required flushing. Therefore the RCx team visited almost every VAV box and flushed the coil. Approximately 471 VAV boxes were reviewed, calibrated and balanced. Various VAV controllers were found non-operational and were replaced, restoring thermal comfort and improving minimum air flow control. The relatively “new” building was brought to its optimal condition.
The air handling units (AHUs) providing air conditioning were maintaining space conditions 24/7/365. The primary energy conservation method was scheduling the AHUs to either shut down or reduce air volumes over the evenings on the weekends, when the library is closed. Exhaust fans associated with these systems are shut down during these periods. Outside air dampers and steam valves at the AHUs were found leaking air and steam wasting energy. New dampers and valves were installed. The fan belts were replaced and the coils were cleaned.
- Bevier Hall, 18% savings
- Coordinated Science Lab, 35% savings
- Illini Union Bookstore, 28% savings
- National Center for Supercomputing Applications, 30% savings
- Psychology Lab, 24% savings
- Siebel Center for Computer Science, 41% savings
- Undergraduate Library, 26% savings