ASHRAE LV-11-C004-2011 Rehab of DDC at Corporate National Training Center-Three Years of Therapy.pdf

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1、Alonzo (A B) Blalock, PE, LEED AP is a Commissioning Manager with Jacobs in the Fort Worth Texas office. Rehab of DDC at Corporate National Training Center- Three Years of Therapy Alonzo (A B) Blalock Member Abstract Environmental conditioning or HVAC contributes to many aspects of a satisfactory wo

2、rker environment. One of the most significant aspects of a satisfactory worker environment is getting the Building Automation System (BAS) to correctly manage the system operations. In some ways, the BAS represents the brain and nervous system for the building body. And thus, careful attention is re

3、quired when attempting rehabilitation or performing brain surgery. When reviewing BAS systems in existing large buildings, it is important to evaluate the entire operation similar to the way a good doctors plan includes a patient stress screening. Various operations can be tested in the Commissionin

4、g processes, including reviewing a listing of Hot-Cold calls and conducting a laptop survey at the sensors to reveal details of system performance similar to an EEG. This Paper will present details of the rehabilitation of a BAS system at a pharmaceutical companys National Training Center campus. Bu

5、ilt in New Jersey in the early 90s, the campus is comprised of three, five-story buildings, with approximately 240,000 total square feet (22300 SM). Each building includes a low temperature air supply system with Series Fan Powered VAV units. Following three years of effort in the continuously occup

6、ied buildings, the project is now complete and already shows much improved living conditions for the Owner. The information of this paper is intended to convey the aspects of a detailed replacement of BAS using descriptions similar to those used by a Medical Professional to treat a patient. The Owne

7、r expressed a desire in and found greater value in the improved reliability of system operations even more than generating minor energy savings. While the improvement in maintenance staffs ability to maintain occupants comfort could not easily be calculated, the Owner believed it represented a major

8、 financial benefit. INTRODUCTION The BAS is vital to properly controlling the equipment that provides employees in modern offices with good environmental conditions. If the building can be compared to a body, then the BAS is the brain and nerve system, leading to similarities in the medical treatmen

9、t of the BAS for various issues. The project, which was suffering from BAS issues in this case, was at a campus of buildings that serve as a National Training Center for a major pharmaceutical manufacturer in New Jersey (refer to Figure 1). LV-11-C00432 ASHRAE Transactions2011. American Society of H

10、eating, Refrigerating and Air-Conditioning Engineers, Inc. (www.ashrae.org). Published in ASHRAE Transactions, Volume 117, Part 1. For personal use only. Additional reproduction, distribution, or transmission in either print or digital form is not permitted without ASHRAES prior written permission.F

11、igure 1: Campus of Buildings in New Jersey DOCTORS FIRST QUESTION How are you feeling? Or where do you hurt? In this case, the response came quickly. The facility staff had been accumulating Hot-Cold calls from occupants for some months but when they reviewed the basis of the call they were unable t

12、o pinpoint and resolve the problem. The BAS system installed to help find solutions was not providing useful information and it sometimes seemed to provide information that was out of balance or contrary to what was expected. Additionally, it often had drop outs and time was wasted keeping the syste

13、m communications working. Overall the issues were similar to a bad cold with a fever and aches but nothing was providing a cure Now for the history- The campus, located near Princeton, New Jersey, included three, five-story buildings, which served many important functions for a major pharmaceutical

14、manufacturer. When looking at the general appearance, the facilities appeared to be well maintained Building One was used as office space for marketing and corporate support functions. Building Two served as the center for all functions on the campus, as it contained a large dining area with food se

15、rvice operations as well as a large multi-purpose area. Building Two also included training rooms where much of the corporate sales force from all over the country was trained. Building Three, while to a large part serving as offices, also housed a central data center and a work out facility, includ

16、ing lockers and showers. The buildings were built and have been in use by this company since 1992. The BAS and mechanical systems were also installed at that time and have not had a major upgrade in the 13 years prior to our initial review in 2005. We were initially selected to perform a Study and t

17、o provide recommendations for system upgrades due to problems 2011 ASHRAE 33with the BAS system. We began our survey by reviewing plans and information on the systems as well as performing a two-week, on-site inspection of the buildings. These steps are similar to a doctor ordering a general lab wor

18、k-up for a patient. Figure 2 depicts the BAS display of AHU data found during our review and Figure 3 is one section of the floor plan, used to find sensors for the reported problems areas. Figure 2: Existing DDC system view of AHU Figure 3: Floor Plan with Zone Sensor locations GETTING THE LAB WORK

19、 DONE - During our reviews, we were given a listing of Hot or Cold calls (refer Figure 4) and a laptop computer that (refer Figure 5) could access the control system from wall sensors. We began by trying to confirm whether the sensors were controlling the VAV terminal units in the problem zones and

20、whether they would respond to changes in temperature. Our review began to show a troubling picture after a few operation tests. There was a failure in performance, in that the VAV controllers were not properly responding to our changes for the system. A separately contracted Test and Balance company

21、 supported our efforts by taking air flow measurements while we were performed changes to the BAS system. These airflow rates gave us information on how the VAV and BAS controllers were working, similar to reviewing an MRI scan for areas that are not readily visible During our patient physical, we a

22、lso removed ceiling tiles to allow for viewing of the VAV terminal units, like an Ear-Nose-Throat review. We checked the supply air temperature in the main VAV ducts and found that it was usually around 55 deg F (13 deg C). We also found that this system used Series Fan Powered VAV terminals. And up

23、on close review of the units, we found that the controllers installed on the VAV units were by a company with best electronics for the 1992 era and with VAV units from a top VAV unit manufacturer. Additionally, the entire system was using electric reheat coils located at the discharge of the units.

24、Even though only a few units were operated to have heating energize during our review, we did find some that did not operate. It appeared that some units had suffered burnout of the heating coils and that became another concern. All of this information was considered in a review of the buildings ele

25、ctric utility bills to confirm whether operating costs were in line with averages for similar facilities. It appeared that the facility maintenance staff had been successful in controlling energy operation by attempting to make changes in setpoints for system operations; however, they found that it

26、required substantial effort and desired to have more reliable operations. 34 ASHRAE TransactionsFigure 4: Hot Call List Figure 5: View of Laptop screen While on-site, we reviewed the Operations and Maintenance information and targeted information on the VAV Controller units. On-site maintenance info

27、rmed us that while they were aware of break downs (or electronic component failures of parts of the Controller units), efforts for support from Control firms resulted in replies that the Controller manufacturer was no longer supporting those units and that a replacement was not readily available. As

28、 to the Ear Nose and Throat examination, we found that tubing was connected between the Controller and the air flow sensor grid in the primary air inlet of the VAV units. The tubing included a Filter (refer to Figure 6), which, according to the specs, should be replaced every year. Due to the inaccu

29、rate flow rates that we found; we felt that plugged filters could be the source of the problems Our later review of current-day Controllers found that no systems appeared to use filters and that item would be eliminated with replacement of the Controllers. Accordingly, the owner was not certain whet

30、her replacement of filters was needed, pending final decision on system rehab. Figure 6: VAV Controller Diagram with filters We also inspected the main HVAC system components and found that the supply system consisted of a built up air system, which used two air fan units connected to a common duct

31、header to supply a total of 140,000 CFM (66100 l/s) of air 2011 ASHRAE 35to a main duct riser. Because each building had approximately of 240,000 Square Feet (22300 M2), it was unusual that the air supply system had a lower volume than the typical ratio of air flow per square foot. Review of the chi

32、lled water system and the cooling coil information indicated that the design engineers had based the system on the concept of Low Temperature Air supply, where the coil leaving air temperature was indicated to be 46 deg F (8 deg C),not the 55 deg F (13 deg C) we found in our survey (refer to Figure

33、7). Figure 7: AHU Schedule with Supply Air temperature for 46 deg F (8 deg C). In general, there were not any complaints that the buildings had ever been totally uncomfortable; however, there were reports of Hot and Cold spots. Based on the information we compiled, we believed we had an understandin

34、g of the issues presented and we concluded our two-week on-site visit with a patient meeting, where we explained our findings using a quickly drawn air flow system diagram (refer Figure 8.) Figure 8: Air System Diagram to show basic system issues. Based on our discussion of the system description an

35、d the air flow diagram, we were to complete our study and follow 36 ASHRAE Transactionsup in a few weeks. This process seems similar to a patient receiving preliminary information on their condition and a prescription for temporary relief, until the final lab results have been reviewed and a follow

36、up visit has been conducted to determine whether surgery is necessary. NOW FOR A PRESCRIPTION - Our primary effort was to prepare an Evaluation Study and Recommendation for the BAS System. The basis of our review was a diagram (see Figure 8) of the HVAC system, which the new BAS system would control

37、. The lab results indicated that many of the Hot Cold calls were resulting from failed Controllers on the VAV units, which were not reporting or responding to the BAS central controls. This seems equivalent to having nerve damage and not able to manage hand motion or control hand functions. During c

38、onversations with the maintenance staff, we learned that the patient had been suffering from drop outs in communication due to break downs in the communication equipment portion of the Controllers, similar to losing feeling in a hand or foots. The future of the study then led to a detail on the cost

39、 value for various items. Our study concluded that replacement of the VAV Unit Controllers was needed to obtain operation of the system and maintain occupant comfort. In addition to the individual Controllers, the main system needed upgrade to meet the staff desires of having alarms to readily trans

40、mit reports to remote locationsa feature available on most all newer BAS systems but not available as an upgrade for the 1992 vintage system on these buildings. A detailed plan for replacement of the VAV Controllers and BAS connection was reviewed and the surgery would include several steps: 1. Shut

41、 down of the VAV unit 2. Removal of the existing Controller 3. Replacement of the VAV Controller 4. Check out of operation with heating coils 5. Air Flow Balance calibration checks 6. Configuration with the BAS system 7. Commissioning test verification for performance The difficulty of this plan was

42、 completing these tasks for roughly 240 VAV units per building and maintaining operation for the facilities while occupied during regular business operations cycles. As we reviewed the operation steps even further, we realized that there might be other opportunities for improving life function for t

43、he system. Because having a well-performing, comfort environment has many benefits to any companys operations, we added the option of doing a complete VAV unit replacement. In that case, Controllers could be factory mounted to the units and checked for connection. It would also be possible to supply

44、 the VAV units with the ECM motor units, which offer much lower energy consumption. Due to the nature of the Series style VAV units, the small VAV motors run whenever there is air circulation. Another option was to have all new electric heating coils for the new VAV units. These options might seem t

45、o be more than a usual minimally invasive operation but would be in-line with a major reconstruction or a hip joint replacement. The total replacement was evaluated and appeared to offer both a correction of the BAS issues and improved energy use and with minimal added costs. After presenting our su

46、mmary to the owners staff, they agreed that complete replacement of VAV units was the best option. We were then directed to begin preparation of the construction documents to be used for bidding of the project. (We were, in effect, scheduling surgery.) TIME FOR THE SURGERY - In order to appropriatel

47、y address all issues, the construction documents were to show all affected VAV units as well as the main HVAC system components including the chillers, pumps, and main air supply units. The plan also entailed 2011 ASHRAE 37replacing the entire BAS system controls while the buildings maintained ongoi

48、ng functions. A construction plan (or surgery schedule) was developed with the owner to allow keeping the building operational. To assist the bidders with knowledge of the system distribution, diagrams of the original BAS system were included in the plans. Addition planning revealed that contractors

49、 would be able to install the backbone of the BAS communication system in a riser from the lower floor engineering control office up through the building in a location of telephone connection closets, where the original BAS system equipment was located. Consideration of the effort for VAV unit replacement, led to the belief that the process could allow for replacement of VAV units at a pace of 4 per night while still taking all the correct protective precautions to keep existing worker spaces