NEBBinar: Retro-Commissioning for Comfort and Energy Efficiency August 21, 2013 0
Moderator Jim Huber, NEBB Vice President and President of Complete Commissioning Jim Huber is the President of Complete Commissioning. He has over 29 years of industry experience, is a Certified Energy Manager, and has extensive experience with BACNET, LON, MODBUS, and other building automation protocols and communication networks. He has programming, tuning, and testing experience with multiple systems and applications, as well as building systems commissioning, sound and vibration measurement, and testing and balancing. 1
Speaker Dave McFarlane, Principal Project Director, Atkins Dave McFarlane is a principal project director in the asset management practice and head of the Retro-Commissioning group for Atkins, one of the world s leading engineering, design, and project management consultancies. Prior to joining Atkins, Dave was the president of Technical Commissioning, Inc. (Fort Myers, FL) and McFarlane, Inc. (Grand Forks, ND). He was a member of NEBB s Commissioning Committee; he chaired the committee in 2003-2004 and rejoined in 2011. Dave serves as an instructor for NEBB s courses in Commissioning and Retro- Commissioning. He speaks at conferences nationwide, and has written numerous articles for a variety of industry publications. 2
Agenda What is Retro-Commissioning Case study: Grand Forks ND County Office Question and Answers 3
Retro-Commissioning A systematic, documented process that identifies and implements low cost operational and maintenance improvements which improve building efficiency and allows the building to meet the current design requirements 4
Retro-Commissioning Ensure that the building meets the Current Facility Requirements (CFR) Reduce energy usage Improve comfort 5
Agenda What is Retro-Commissioning Case study: Grand Forks ND County Office Question and Answers 6
Grand Forks County Office Retro-Commissioning 7
Grand Forks Country Office Seven story - 140,000 square feet Five floors office space w/conference rooms Meeting rooms on sixth floor Mechanical room on the 7 th floor 8
Interior/exterior walls and conference rooms Floors 1-5 9
Interior/exterior walls and conference rooms Floor 6 10
Interior offices Perimeter offices 11
County Commissioners Chambers 12
Perimeter link Meeting room 13
Establish baseline Review the past 2-3 years energy bills Convert to MM BTU ft2/year Energy intensity is ~ 151,000 BTU/ft2/yr Session 21 Energy Savings 14
Natural Gas 16,000 14,000 12,000 10,000 8,000 6,000 4,000 2,000-1 2 3 4 5 6 7 8 9 10 11 12 Premodification Gas Use 15
Electrical Usage KWH 330,000 280,000 230,000 180,000 Premodification KWH 130,000 80,000 1 2 3 4 5 6 7 8 9 10 11 12 16
Electrical Demand KW 800 700 600 500 400 300 200 100 0 1 2 3 4 5 6 7 8 9 10 11 12 Premodif ication KW 17
Compare baseline to typical For North Dakota typical energy intensity: 93,000 BTU/ft2/yr County office energy intensity: ~ 151,000 BTU/ft2/yr Projected savings achievable through retrocommissioning: $45,000 annually 18
Discovery phase Determine what is wrong Review documents, plans and specs Interview maintenance staff 19
Plans and specs showed VAV boxes with 2-way valves 4 VAV air handlers 4 boilers 20
AHU Quadrants Session 21 Energy Savings 21
Plans and specs showed HW pumps and fans with VFD s Pump and fan VFD s 22
Discovery and maintenance staff perspectives Building had electric baseboard supplement heat Too many occupant complaints about temperature controls Lack of understanding of Building Management System (BMS) Systems in overridden and in manual control BMS system not used to potential 23
Light shelves 24
Heating pumps VFD 60 Hz 25 100% Leaking reheat valves
Site investigations Fresh air dampers open on night set back Control sequence cooled building Building in occupied mode Occupied air flow: meeting/conference rooms Space stats not controlling within 1 o F Occupants had full thermostat control Mixed air control set at a constant 55 F o 26
Site investigations Equal occupied and unoccupied heating variable air volume (VAV) set points Min/max heating VAV set points are the same Equal unoccupied interior and exterior zones air flow 27
Site investigations Boilers reset to 120 during summer months Heat from dimmer switch 28
Site investigation Electric baseboard on whenever OA below 50 F Duct static pressure sensor set at 2 pressure Most VAV boxes call for reheat Most VAV boxes damper position 50-75% in summer 29
Site investigations Outdoor CO2 is 370 PPM. Indoor CO2 is 425 PPM Chiller energized at 50 F OAT Many VAV min / max set points had been occupant complaint adjusted Room registers read between.5 and 4.0 CFM / Ft2 Building positive, then negative 30
RA fan and SA fan not tracking 31
Analysis phase Computer modeling Determine if we can predict the current energy usage before changes are made 32
Corrective action items Recalculate new air flows based on the actual people, lights, equipment, glass walls and roof loads. Use ASHRAE 98% design Use actual people loading for fresh air 33
Analysis phase Actual operating data Total fan air flow Actual fan static pressures Actual fan amperage readings System type, fan wheel type and fan speed Actual run times 34
Analysis phase Actual data Average Min / Max set points Occupied / unoccupied set points VAV occupied unoccupied set points Fan type and fan speed Run times Actual fresh air CFM 35
Analysis phase Actual operating data Total fan discharge temp Hot water temps Chilled water temps Space temp Type of fin tube heat and fin tube parameters 36
Analysis phase: actual space data Actual people, light load, equipment load Actual occupied times Actual space temperatures Actual glass area and parameters Actual roof area, wall area and parameters 37
Analysis phase: actual utility cost data Gas cost per therm KWH cost KW demand cost Auxiliary fuel costs Local degree days / bin temperatures 38
Analysis phase DOE 2 or Super DOE Crunch the numbers and compare 39
Natural Gas 16,000 14,000 12,000 10,000 8,000 6,000 4,000 2,000-1 3 5 7 9 11 Projected Gas Use Premodification Gas Use 40
Annual Natural Gas Summary 150,000 120,000 90,000 60,000 Premodification Projected 30,000-41
Electrical Demand KW 800 700 600 500 400 300 200 100 0 1 2 3 4 5 6 7 8 9 10 11 12 Projected KW Premodification KW 42
Annual Electrical KW Demand Summary 8,000 7,000 6,000 5,000 4,000 3,000 2,000 1,000 - Premodification Projected 43
Electrical Usage KWH 330,000 280,000 230,000 180,000 Projected KWH Premodif icatio n KWH 130,000 80,000 1 3 5 7 9 11 44
Annual Electrical KWH Summary 2,500,000 2,000,000 1,500,000 1,000,000 Premodification Projected 500,000 0 45
Office Energy Intensity Current Intensity is ~ 151,000 BTU/ft2/yr Area Average ~ 93,000 BTU/ft2/yr Computer modeling ~ 85,000 BTU/ft2/yr 46
Corrective action items Make the corrections needed to obtain the results outlined in the modeling. Rebalance air and water flows to new ASHRAE 98% requirements Session 21 Energy Savings 47
Repair leaky valves 48
49 Eliminate restrictive duct
Corrective action items Adjust throttling range and dead band on all VAV thermostats and AHU Controllers 50
Improper Control - Too tight 51
Improper Control - Too Loose 52
Proper Control 53
Adjust occupied/unoccupied sequence 54
Fixes and corrective actions Rezone for interior exterior zones Set VAV box up with different occupied/unoccupied min/max Set conference room VAV box to standby Unoccupied interior VAV set to zero air flow Set 6th floor conference room VAV s to standby mode 55
Fixes and corrective actions Lock thermostats between 68 and 75F Reset discharge temperature on cooling Reset hot water 140 to 180F De-energize electric fin tube above 30 F De-energize the fin tube in the unoccupied mode Rotate the fin tube usage off for 1 of 5 minutes Shut boiler off at 40F unoccupied 56
Acceptance phase Energy Procedures Winter temps-- 70-74 F Summer temps 73-77 F No space heaters Monitor usage for one year 57
58 Grand Forks County Office Retro-Cx Results
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Yearly energy usage per square foot Pre-modification 151,000 BTU/FT² Typical 93,000 BTU/FT² Modeling 85,000 BTU/FT² Actual: 76,000 BTU/FT² 65
Results 2002-2012 Gas 29.8 % $417,200 KW-hr 45.9 % $642,600 Demand 26.3 % $368,200 Total 100 % $1,400,000 Energy levels have stayed at projected levels for the past eleven years 66 \
Three years after RCx 67
68 Question and Answers
Contact information Jim Huber, NEBB Vice President and President of Complete Commissioning Tel: +1.301.877.2260 Email: JHuber@completecx.com Dave McFarlane, Atkins Tel: +1.239.791.8771 Ext. 460-1021 Email: Dave.McFarlane@atkinsglobal.com 69
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