CxI (Commissioning Investigations): Uncovering Energy Waste, Operational Issues and Other Offences Found Within Existing Buildings

Transcription

1 CxI (Commissioning Investigations): Uncovering Energy Waste, Operational Issues and Other Offences Found Within Existing Buildings Ryan Stroupe, PG&E Pacific Energy Center Arik Cohen, kw Engineering

2 AIA Quality Assurance The Building Commissioning Association is a Registered Provider with The American Institute of Architects Continuing Education Systems (AIA/CES). Credit(s) earned on completion of this program will be reported to AIA/CES for AIA members. Certificates of the Completion for both AIA members and non-aia members are available upon request. This program is registered with AIA/CES for continuing professional education. As such, it does not include content that may be deemed or construed to be an approval or endorsement by the AIA of any material of construction or any method or manner of handling, using, distributing, or dealing in any material or product. Questions related to specific materials, methods, and services will be addressed at the conclusion of this presentation. 2

3 Learning Objectives 1. Attendees will improve their ability to decipher building performance data collected from energy management systems or dataloggers. 2. Attendees will improve their ability to decipher control system graphics and identify potential performance problems observable in these screen captures. 3. Attendees will improve their ability to decipher data collected from functional testing to diagnose building performance problems. 4. Attendees will improve their ability to weigh the information collected from a variety of sources to ultimately determine the basis of building system faults. 3

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5 The Energy Detectives Directive: Use the following techniques to determine the source of energy waste and building performance issues: Observation of crime scene Scanning printed evidence and other documents Forensics kit (measurement tools) Surveillance Utility billing data Trend data Data logger data Interrogation (interviews of facility staff)

6 Case 1: Early Pursuit 1,800 Hourly Usage (kwh and Temp) 1,600 1,400 1,200 kwh 1, OSA Temperature

7 Interval Energy/Climate Data Scatter Meter Energy Consumption (kwh) Temperature 7

8 Interval Energy/Climate Data Scatter 3

9 Case 2: The Bloated Building Clue 1: Office building Clue 2: About 200 therms/day for non-heating end-uses 9

10 Clue 3: Served by 8 large air handlers VAV w/ re-heat Exhaust Air Return Air Outside Air VFD COLD DAMPER REHEAT COIL Exterior Zone DAMPER REHEAT COIL DAMPER Interior Zone REHEAT COIL DAMPER REHEAT COIL DAMPER Interior Zone DAMPER DAMPER REHEAT COIL Exterior Zone DAMPER REHEAT COIL 10

11 @ OAT of 61.4 F, SAT Setpoint should equal 55.8 F 11

12 SAT cold in cooler weather SAT not meeting setpoint in warm weather Economizer closed 12

13 AHU-1 AHU-8 C P Picture of balancing valve on air ha

14 Case 2: The Bloated Building - Recommendations Step 1 Rebalance chilled water distribution system so that all air handlers getting design flow when chilled water valve at 100% Step 2 Analyze VAV boxes to find zones that are always calling for cooling rouge zones. Step 3 Fix rouge zones Step 4 Remove OAT based SAT Reset and install Trim and Respond SAT reset Step 5 In controls create VAV box summary screen (by AHU) to allow staff to quickly determine rouge zones. Step 6 Train staff on fixing rouge zone as they pop up over time 14

15 Case 3 Reverse Pivot 15

16 Case #4: The Frigid Librarian Located in basement. Space connected to glazed front façade through opening in ground floor. Minimal occupancy. Victim Interview: Only on the warmest days is the library not cold.

17 Trend Analysis: VAV 1-3 Cooling Set-point Zone Temperature Heating Set-point 17

18 2008 VAV Box Analysis

19 2010 VAV Box Analysis

20 Functional Test Results for VAV 1-3 Tested thermostat accuracy Checked box inlet condition Verified air flow at different operating modes Minimum cooling Maximum cooling Heating When heating, measured entering & leaving water & air temperatures. Water Air Pass/fail Entering 184 F 59.9 F Leaving 138 F F Delta 46 F 86 F

21 Single-Line of Duct Run 142 F 133 F 99 F 85 F 73 F Where did the heat go? 21

22 Infrared Image of Ductwork Upper duct is from VAV1-3 Isolation damper located here 22

23 Relocation of Re-heat Coils Moved re-heat coil from here to here. 23

24 2017 Analysis: VAV B-1 (formerly VAV1-3) 24

25 2017 Analysis: VAV 2-4 No set backs 25

26 2017 Analysis: VAV 2-5 Zone struggles to meet set-point; air cooled when heat is needed. 26

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28 Case #4 Conclusions Long duct runs after reheat coils are not ideal. Un-insulated ductwork is not ideal. Testing and re-testing VAV box performance should be a regular ongoing commissioning activity or operations and maintenance practice. Continuous trending of zone temperature and zone setpoints is desirable. UT software can be used to analyze collected data. Software download: Training videos:

29 Case #5: Bent out of Shape in Monterey Location: Presidio of Monterey Year constructed: 1977 (Major Renovation ) Square footage Medical/Lab: 22,642 - Medical staff offices - Examination rooms - X-ray - Laboratory - Pharmacy - No surgical capability - Hours of Operation Monday Friday: Saturday & Sunday: Closed

30 Building Has One Air Handler 26,925 CFM Package Unit with DWDI Air Foil Fans - 50 HP SF motor - 25 HP RF motor - Both fans with VFD s 26,180 max CFM cooling coil 10,670 max CFM heating coil

31 Common Packaged Unit Issues Economizers Refrigerant Charge Low Airflow Cycling fans (occupied) Fans On (unoccupied) Simultaneous Heating & Cooling No Outside Air Intake % of Units PIER Buildings Program Design Guide: Big Savings on Small HVAC Systems

32 Airside Economizer April 2015

33 Airside Economizer July 2015

34 Broken Economizer Line-up 1: broken actuator motor 2: incorrect control logic 3: damper leakage 4: stripped linkage 5: sensor calibration

35 Return Air Damper

36 Return Air Leakage Calculation Traverse 1 Left 1 2 avg Right 1 2 avg total Flow Flow CFM DeltaP inches Traverse avg total CFM DeltaP inches Assumed OSA TMY data RA 76 OSA 60 delta T 16 avg delta T BTU/hr , ton kw/ton kw hours kwh $/kwh $ $ $624.53

37 July 2017

38 October 2017

39 Case #5 Conclusions Identifying an issue does not always lead to repair. There are numerous ways for economizers to fail. Testing and re-testing air-side economizer performance should be a regular ongoing commissioning activity or operations and maintenance practice. Continuous trending of outside, return, mixed and supply air temperatures along with supply fan status is desirable. UT software can be used to analyze collected data. Software download: Training videos: Don t forget to maintain damper blade seals.

40 Case 6: Ripley's Believe It or Not 40

41 Case 7: Under Pressure 41

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43 Building BAS Tag Air Distribution Systems Library / L-Tower Library Single VAV AHU with reheat. Science Science Six VAV AHUs with reheat. Notes Undergoing gut renovation. Served by HW and CHW central plants. 100% pneumatic. 100% DDC down to zone level. Administration Admin Two dual duct AHUs. 100% DDC down to zone level. Business Business Three air handlers: two dual duct, one constant volume single zone. Learning & Resource Center Student Services LRC SS Two VAV AHUs with reheat, five DX AC units, four fan coils. Three VAV AHUs with re-heat. DDC controls start/stop schedules and monitors CD, HD and some space temperatures. Everything else is pneumatic. 100% DDC down to zone level. 100% DDC down to zone level. Student Union SU One VAV AHU with reheat, three FC units, kitchen MAU. Technology Tech 14 single zone AHUs and associated EFs, 3 fan coil units Wray Wray Four single zone air handlers, one HV. Child Development Center 100% DDC down to zone level. 100% DDC down to zone level. DDC only controls start/stop schedules and monitors zone temperatures and central plant chilled water supply and return temps. Dedicated boiler system. CDC Served by DX systems. Not part of scope because not served by the central plant. KDA KDA Served by DX systems. Not part of scope because not served by the central plant. Dedicated boiler plant. GYM GYM Served by DX systems. Not part of scope because not served by the central plant. Dedicated boiler plant. Wrestling room AJA AJ Wrestling room Admin Justice Admin Justice Served by DX systems. Served by DX systems. 13 DX AC units, 7 DX FC units Not part of scope because not served by the central plant. Dedicated boiler plant. Not part of scope because not served by the central plant. Dedicated boiler plant. Not part of scope because not served by the central plant. Dedicated boiler plant. 43

44 Case 8: Running Wild 44

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46 Central Plant Metered kw and Outside Air Temperature Power (kw) /16/2017 5/23/2017 5/30/2017 6/6/2017 6/13/2017 RHCC Central Plant Power, kw OAT from LAX, F Weekend Temperature ( F) 46

47 47 Admin Business CDC LRC Science Student Services Student Union Tech Wray AHU-1 AHU-2 AHU-1B AHU-2B AHU-Photo AC-A AC-B AC-C AC-1 AC-2 AC-3 AC-4 AC-5 AHU-1 AHU-2 FC-1 FC-2 FC-3 FC-4 FC-5 FC-6 AHU-1 AHU-2 AHU-3 AHU-4 AHU-5 AHU-6 AHU-1 AHU-2 AHU-3 AHU-1 FC-1 FC-2 FC-3 MAH-1 AHU-1A AHU-2A AHU-3A AHU-4A AHU-5A AHU-6A AHU-7A FC-1A FC-2A AC-1B AC-2B AHU-1B AHU-3B AHU-4B AHU-5B AHU-1C AHU-2C FC-1C AHU- Dining AHU-TV Studio AHU-Music AHU-Theater Admin Business CDC LRC Science Student Services Student Union Tech Wray AHU-1 AHU-2 AHU-1B AHU-2B AHU-Photo AC-A AC-B AC-C AC-1 AC-2 AC-3 AC-4 AC-5 AHU-1 AHU-2 FC-1 FC-2 FC-3 FC-4 FC-5 FC-6 AHU-1 AHU-2 AHU-3 AHU-4 AHU-5 AHU-6 AHU-1 AHU-2 AHU-3 AHU-1 FC-1 FC-2 FC-3 MAH-1 AHU-1A AHU-2A AHU-3A AHU-4A AHU-5A AHU-6A AHU-7A FC-1A FC-2A AC-1B AC-2B AHU-1B AHU-3B AHU-4B AHU-5B AHU-1C AHU-2C FC-1C AHU- Dining AHU-TV Studio AHU-Music AHU-Theater

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49 Case 8: Running Wild - Recommendations Step 1 Add split system to area served by FC-1 Step 2 Install Controls Hardware Upgrade and all air handler pneumatic controls to DDC controls. Business building 3 air handlers Wray 4 air handlers Step 3 Revise Controls Programing Connect the new DDC controls to the BAS and create a new CHW valve summary screen in the BAS. Enable the chilled water plant based on CHW valve positions. When all CHW valves are 0% open (ie, all AHUs are scheduled off) for 15 minutes, turn OFF the central plant. When any three (adjustable) valve is open more than 50% for 15 minutes, turn ON the central plant 49

50 Case 8: Running Wild - Recommendations Admin Business CDC LRC Science AHU-1 AHU-2 Measure Number 0% 0% AHU-1B AHU-2B AHU-Photo 0% 0% 4% Measure Description AC-A AC-B AC-C 8% 8% 8% AC-1 AC-2 AC-3 AC-4 AC-5 AHU-1 AHU-2 FC-1 FC-2 FC-3 FC-4 FC-5 FC-6 Peak Savings (kw) 10% 10% 10% 10% 50% 10% 10% 33% 33% 33% 33% 42% 45% AHU-1 AHU-2 AHU-3 AHU-4 AHU-5 AHU-6 15% 20% 20% 20% 90% 80% Student Services AHU-1 AHU-2 AHU-3 Annual Energy & Cost Savings Electricity Savings (kwh/yr) Gas Savings (therms/yr) Total Cost Savings 10% 10% 80% CO 2 Savings (tons) AHU-1 FC-1 FC-2 FC-3 MAH-1 Student Union Measure Cost 30% 25% 15% 7% 0% AHU-1A AHU-2A AHU-3A AHU-4A AHU-5A AHU-6A AHU-7A FC-1A FC-2A AC-1B AC-2B AHU-1B AHU-3B AHU-4B AHU-5B Tech AHU-1C 25% Financial Metrics AHU-2C 25% FC-1C Potential Incentive 25% 25% 25% 25% 25% 25% 25% 25% 25% 25% 25% 25% 25% 25% 25% 25% Net Measure Cost Wray AHU- Dining AHU-TV Studio AHU-Music AHU-Theater MIRR 15% 15% 15% 15% 15% Simple Payback RCx-1 Add stand alone cooling to select areas in Student Union, Add DDC controls to air handler in Wray and Business Buildings and Revise controls and graphics to enable automated on/off control of central plant ,031, $ 123, $ 162,000 $ 84,456 $ 77, %

51 Case 9: Design Intent - NOT 51

52 Secondary Loop Chilled Water Differential Temperature and VFD Speed Speed (%) Temperature ( F) 0 5/16/2017 5/23/2017 5/30/2017 6/6/2017 6/13/2017 CHWP 2A Speed Secondary Loop CHW DT Weekend 0 52

53 53 Admin Business CDC LRC Science Student Services Student Union Tech Wray AHU-1 AHU-2 AHU-1B AHU-2B AHU-Photo AC-A AC-B AC-C AC-1 AC-2 AC-3 AC-4 AC-5 AHU-1 AHU-2 FC-1 FC-2 FC-3 FC-4 FC-5 FC-6 AHU-1 AHU-2 AHU-3 AHU-4 AHU-5 AHU-6 AHU-1 AHU-2 AHU-3 AHU-1 FC-1 FC-2 FC-3 MAH-1 AHU-1A AHU-2A AHU-3A AHU-4A AHU-5A AHU-6A AHU-7A FC-1A FC-2A AC-1B AC-2B AHU-1B AHU-3B AHU-4B AHU-5B AHU-1C AHU-2C FC-1C AHU- Dining AHU-TV Studio AHU-Music AHU-Theater Admin Business CDC LRC Science Student Services Student Union Tech Wray AHU-1 AHU-2 AHU-1B AHU-2B AHU-Photo AC-A AC-B AC-C AC-1 AC-2 AC-3 AC-4 AC-5 AHU-1 AHU-2 FC-1 FC-2 FC-3 FC-4 FC-5 FC-6 AHU-1 AHU-2 AHU-3 AHU-4 AHU-5 AHU-6 AHU-1 AHU-2 AHU-3 AHU-1 FC-1 FC-2 FC-3 MAH-1 AHU-1A AHU-2A AHU-3A AHU-4A AHU-5A AHU-6A AHU-7A FC-1A FC-2A AC-1B AC-2B AHU-1B AHU-3B AHU-4B AHU-5B AHU-1C AHU-2C FC-1C AHU- Dining AHU-TV Studio AHU-Music AHU-Theater

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60 Case 9: Design Intent NOT! - Recommendations Replace 3-way valves with 2-way valve at chilled water coils We counted 15 chilled water coil valves that are three way. Three way valves are not designed to work with variable flow systems. We noted one air handler with no valve at all and chilled water running through the coil continuously. Some critical central plant control sequences are overridden or not working per design intent. These need to be re-programed The dp sensor controlling the secondary pumps is too close to the outlet of the pump Annual Energy & Cost Savings for proper variable control, need to move Peak Gas Savings Measure Description Savings further out on the line. (therms/yr) (kw) Electricity Savings (kwh/yr) Total Cost Savings CO 2 Savings (tons) Measure Cost Potential Incentive Financial Metrics Net Measure Cost MIRR Simple Payback Replace existing air handler 3-way valves with 2- way valves (15), Relocate the DP Sensors that Control the SCHWPs and Revise PCHWP Controls to Optimize CHW Distribution System , $ 29, $ 102,000 $ 29,420 $ 72, %

61 Case 10: Flow in all the wrong places 61

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64 Case 11: The Setpoint that Wasn t 64

65 Case 11: The Setpoint that Wasn t Temperature ( F) CWST CWST Setpoint Cooling Tower Fan Speed (%) Speed (%) Outside Air Temperature ( F) 65

66 Case 12: Getting into Hot Water There are two commissioning issues shown in the graphed data. Identify both issues and describe how each is validated across multiple data sets Flue Temp Flow in GPM boiler leaving water temperature boiler return water temperature Temperature/F Amps/GPM boiler combustion fan amps /23/14 0:00 7/23/14 12:00 7/24/14 0:00 7/24/14 12:00 7/25/14 0:00

67 Case #13: Pump it Up

68 System Diagram with Constant Speed Pumps Portland Energy Conservation Inc SW 5th Avenue, Suite 700, Portland Oregon 97201, , FAX , Air Cooled Chiller Pump CHP1 Suction Diffuser (Typical) Pump CHP2 Training AHU Rooftop AHU Ice Storage Ice Storage 68

69 Calculate Required Pressure (Head) Design Head Loss = 106-Ft W.C. Calculated head loss = 55.3-Ft W.C. about 50% of the design value Pipe Length Ft 2 floors; allow 12-ft each 24.0 Top of AHU Basement; allow 8.0 Subtotal Elevation Diff 42.0 Supply & Return Pipe 84.0 Elbows 13-Ea 65.0 X-Y plane offsets 24.0 Pipe, Equivalent Length Head Loss Ft. W.C. Piping Allowance 5.7 Contingency 20% 1.1 Cooling Coil 5 psi 11.5 Chiller 10 psi 23.1 Ice Depth 3 psi 6.9 Tri Svc Vlv 3 psi 6.9 Total System Pressure Drop 55.3 Check Flow Needed 100 gpm ok AHU = Air Handling Unit psi = pounds per square inch gpm = gallons per minute

70 Pump Test Set-up Conduct Pump Test Control: Pump P-2 in lead Assure Pump P-2 is operating Assure Pump P-1 is isolated Lock & Tag-Out Breaker Pump Test CHW Supply P-1 Closed P-2 Open

71 No-Flow Test to Determine Impeller Size The head produced (108.8 Ft W.C.) is very close to the 9-1/2 impeller line; a stock impeller for this pump line. Wear ring clearances could account for the difference. Shut off test forces a known flow condition of 0 gpm

72 100% Flow Test With the pump running wide open, we read average of 93.5 Ft. W.C. of head Projecting the measured head over to the impeller curve, then projecting down from that point indicates about gpm of flow.

73 Develop System Curve We can plot others using the square law (Derived from the Darcey- Weisbach equation) P New = P Old x (Flow New /Flow Old ) 2 Our test point is one point on the system curve Head ft.w.c. Flow Rate gpm

74 Chilled Water Pump Testing and Remedial Action Develop & Evaluate Alternative Solutions Trim the existing impeller to smaller size Change to a lower speed motor Reduce rotational speed using a Variable Frequency Drive Throttle flow of the existing pump to the design flow rate

75 Trim Impeller Alternative Projecting the required flow up to our system curve tells us the actual head required by the system at that flow rate Sketching an impeller curve through the intersection of our system curve and the design point shows we could get what we need with a 7-1/4 or so impeller

76 Throttle Pump Alternative We could also get what we need by throttling to design with the existing impeller, which would generate a new system curve through that operating point

77 Chilled Water Pump Testing and Remedial Action Table 1 Summary Pump Modification Alternatives Parameter Base Case Trim Impeller Lower Speed Throttle w/ VFD 5 Flow Impeller Size (Inches Diameter) 9½ 7-3/4 9½ 9½ Rotational Speed (RPM) 1,750-RPM 1,750-RPM 1,349-RPM 1,750-RPM Flow Rate (gpm) gpm gpm gpm gpm Pumping Head (Ft. W.C.) 93.5-Ft. W.C Ft. W.C. Not Calculated Ft. W.C. Pump Break Horsepower (BHP) BHP 2.63-BHP 2.13-BHP 4.65-BHP Pump Power Demand (kw) kW 2.18-kW 1.86-kW 3.85-kW Annual Power Use (kwh/yr) 3 18,115-kWH/Yr 9,529-kWH/Yr 8,161-kWH/Yr 16,847-kWH/Yr Annual Power Cost ($ / Year) 4 $2,898 / Year $1,525 / Year $1,306 / Year $2,696 / Year Notes 1. Values interpolated from pump curve, Figure Electric demand (kw) is calculated assuming motor efficiency of 91.2%. 3. Annual power use is determined from 4,380-hours per year operations based on PEC trend data. 4. Annual electric power costs are based on the PEC s average rate during f $0.16 / kwh. 5. Calculations include an added efficiency reduction of 5% due to internal losses of the VFD.

78 Chilled Water Pump Testing and Remedial Action Disassemble Pump Remove impeller Take impeller to machine shop with dedicated, digitally controlled, grinding machine Grind impeller to a 7-1/4 diameter and dynamically rebalance Re-assemble Pump Replace the pump seal and gasket Reprogram lead-lag controls

79 Case #13 Conclusions Return on Investment Calculation Pump Impeller Trimmed Implementation Cost $2,479 Electric Demand Savings 1.96 KW Electric Energy Savings 9,529 kwh / year Annual Power Cost Saved $0.16/kWH Simple Payback Period 1.8 years New Pump Seal and Gasket Need to be diligent about keeping Pump #1 as lead. Pump #2 allows us to recreate this finding and pump test

80 Case 14: Hanging in the Balance Case 15: Pot Shot

81 Case 16: Night Light Total power Site and interior lighting Miscellaneous & transformer Chiller Boiler pump Other mechanical

82 Lighting Data Only kw 5 4 Exterior Lights Interior Lights 0 0:00 3:00 6:00 9:00 12:00 15:00 18:00 21:00 0:00 82

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84 Arik Cohen, P.E. Principal kw Engineering th St #300 Oakland, CA P: E: Ryan Stroupe Building Performance Program Coordinator PG&E Pacific Energy Center 851 Howard Street San Francisco, CA P: E: