technical guidelines on retro-commissioning · 1. introduction. 5. technical guidelines on retro...
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Technical Guidelines on Retro-commissioning
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Seminar on Retro-commissioning in Hong Kong
Section A1. Introduction2. TG (RCx) Framework
Section B3. How we start 4. Example 5. Common difficulties & Solution
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1. Introduction
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Retro-commissioning web page
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1. Introduction
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Technical Guidelines on Retro-commissioning
Acknowledgement
What is Retro-commissioning ?
A cost-effective systematic process to periodically check an existing building’s performance.
The process identifies operational improvements that can effectively save energy and thus lower energy bills and improve indoor environment
“Retro-commissioning” covers the scope of “existing building commissioning”, “re-commissioning” and “continuous commissioning”.
Retro-commissioning is…
1. Introduction
Why retro-commissioning ?
We completed Energy Audit already!
1. Introduction
Retro-commissioning is different from Energy Audit
RCx is more focused on checking whether the energyconsuming systems operate properly as design or users’requirements and to identify area of improvements
Besides, RCx has an implementation of Energy SavingOpportunity (ESO) and on-going commissioning plan forthe building owners to maintain the building operating inhigh energy efficiency level.
1. Introduction
Retrofitting vs Retro-commissioning
Retrofitting can apply to new or existing building and involves upgrading or replacing equipment such as HVAC (boilers, chillers, …), lighting (fluorescent Lamps vs LEDs ), installing variable frequency drives (VFDs) and other energy-efficient measures.
1. Introduction
RCx applies to existing buildings and seeks to improve the functioning of equipment & controls without relying on the need for replacement.
RCx may involve corrective actions/quick fix during the investigation, measurement & verification procedures, functional testing and diagnostic monitoring.
RCx pushes towards an on-going commissioning effort
Retro-commissioning : -
1. Introduction
4 Workstages of RCx
Sample Technical Approach of RCx
Forms or checklist for RCx
2. TG(RCx) FRAMEWORK
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4 workstages
Stage 1: Planning
Stage 2: Investigation
Stage 3: Implementation
Stage 4: On-going commissioning
2. TG(RCx) FRAMEWORK
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• Gather information from stakeholders, documentation
• Arrange meeting and interview
• Conduct walk-through Inspection
• Develop RCx plan for agreement with stakeholders
• Forms template developed in TG to facilitate theusers to carry out RCx
Stage 1: Planning
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• Conduct site survey and identify current facilities
requirement
• Perform system adjustments and quick fix
• Conduct data logging and trending
• Short term diagnostic, monitoring and functional test plans
• Identify potential energy saving measures and improvements
• Forms templates are developed in TG(RCx)
• Investigation Report
Stage 2: Investigation
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• Implementation of selected energy saving opportunities
- Proposed by RCx team and agreed by Stakeholder
- Suit budget, minimize disturbance to users
• Performing verification
- Effectiveness of the implemented items
• Develop a RCx Final Report
• Training for O&M Staff (maintain the RCx benefits)
Stage 3: Implementation
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• To ensure “high” energy performance maintained after RCx
• To develop a ongoing commissioning plan
• key indicators such as
Electricity Bill, satisfaction levels of occupants, etc…
• To arrange training for O&M staffs
• Continuous monitoring – review and update
Stage 4: On-going commissioning
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Section 2
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Technical Approach Example on Retro-commissioning
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Seminar on Retro-commissioning in Hong Kong
1.How we start?2.Examples3.Common difficulties & solutions
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Venues
Building portfolio
Annual electricity consumption?
Accessibility?
System complexity?
Considerations
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How we start?
People
Operators / technicians
Engineers
Maintenance contractors
Equipment/ System Suppliers
Services Providers?
Considerations
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How we start?
Investment & Return
Venues (accessibility?)
People (internal-staff/ external?)
Together with retrofit?
Phasing?
Environmental concerns?
Considerations
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How we start?
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Technical approach examples
16 floor Office building with 24 hours facilities
Floor area: ~37,800m2
Annual electricity consumption ~7,060,000kwh
Water cooling chiller system
Planning Stage
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Technical approach examples
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Data collection
Familiar with the buildings
Facility / Equipment Observation
Understanding the building
• Drawings/ documents• Site conditions• Equipment's rating & conditions• Cooling load requirements• Users requirements/ constrains
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Technical approach examplesData handling and checking
Data quality checking and fixing
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Analysis Stage
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Cooling tower performance
Cooling towers
Facility / Equipment
Technical approach examples
Outdoor temp
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Cooling tower performance
N+1 Cooling towers with VSD vans
Observation 1 chiller with 1 Cooling tower
1 chiller with 2 Cooling tower
Cooling Tower Fan + Condensate water pump Power consumption
Load percentage
Technical approach examples
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Cooling tower performance
Cooling tower set point reset
Facility / Equipment Observation
Technical approach examples
CT leaving water temp. set pt.
VSD Chiller COP
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Chillers Plant Saving
Entering Condensate water Temperature
35 degree
30 degree
25 degree
20 degree
15 degree
• Different CWST gives different Chiller performance curve
• Try to lower the CWST hence to improve COPHelp the chiller lift and hence improve COP
Building load Characteristic
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100
200
300
400
500
600
700
800
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Hou
rs
Month
Chiller load distribution
<= 500.00 >500.00 to <=875.00 >875.00 to <=1250.00 >1250.00 to <=1625.00 >1625.00 to <=2000.00
>2000.00 to <=2375.00 >2375.00 to <=2750.00 >2750.00 to <=3125.00 >3125.00 to <=3500.00 > 3500.00
Mode table
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Operation Mode Building load
No. of chiller reuiqred Chiller to operate
No of cooling tower to operate
A < 500kW 1 WCC1 2
B 500kW < and < 1700kW 1 HRC1/HRC2/WCC2/WCC3 2
C 1700kW < and < 3000kW 2
HRC1/HRC2/WCC2/WCC3 and
HRC1/HRC2/WCC2/WCC3
3
D > 3000kW 3
HRC1/HRC2/WCC2/WCC3 and
HRC1/HRC2/WCC2/WCC3 and
HRC1/HRC2/WCC2/WCC3
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Loading range
Suggested operation
mode Loading rangeSuggested
operation mode Loading range
Suggested operation
mode RemarksJanuary < 500kW A 500kW < and < 1700kW B > 1700kW B Note 1
February < 500kW A 500kW < and < 1700kW B > 1700kW B Note 1
March < 500kW A 500kW < and < 1700kW B > 1700kW B Note 1
April < 500kW A 500kW < and < 1700kW B > 1700kW B Note 1
May 500kW < and < 1700kW B 1700kW < and < 3000kW C > 3000kW C -
June 500kW < and < 1700kW B 1700kW < and < 3000kW C > 3000kW C -
July 500kW < and < 1700kW B 1700kW < and < 3000kW C > 3000kW D -
August 500kW < and < 1700kW B 1700kW < and < 3000kW C > 3000kW D -
September 500kW < and < 1700kW B 1700kW < and < 3000kW C > 3000kW D -
October < 500kW A 500kW < and < 1700kW B > 1700kW B Note 1
November < 500kW A 500kW < and < 1700kW B > 1700kW B Note 1
December < 500kW A 500kW < and < 1700kW B > 1700kW B Note 1
Notes1. If loading more than 1 chiller capacity, extra chiller to be kick in
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Chillers Plant Saving
Estimation (by computer simulation)
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2
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Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
COP
Date
Chiller Plant Efficiency (kW/kW) vs time
Annual average COP improvement(estimated by simulation)
Approx. 5 -10%
Technical approach examples
Implementation Stage
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Actions
With maintenance contractor• On-site data verification • Sensors replacement
With CCMS/ BMS service provider• Enable data trend logging• Enhance data storage• Review current control sequence
Sensors & data checkingTechnical approach examples
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Operation Mode Building load No. of chiller reuiqred Chiller to operateA < 500kW 1 WCC1B 500kW < and < 1700kW 1 HRC1/HRC2/WCC2/WCC3
C 1700kW < and < 3000kW 2HRC1/HRC2/WCC2/WCC3 and
HRC1/HRC2/WCC2/WCC3
D > 3000kW 3
HRC1/HRC2/WCC2/WCC3 and HRC1/HRC2/WCC2/WCC3 and
HRC1/HRC2/WCC2/WCC3
Actions
• Understanding the technical principle• Understanding the site condition / current
operation requirements (effects to the end users)
• Agree on the test procedures and contingency plan
• One week trial• Ensure data logging
Technical approach examples
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CT Trial Setting
Scenarios Trail duration No. of chiller CT VSD Fans' speed
settingNo of cooling
tower to operate Remarks
Baseline 8:30am - 5:30 pm 2 Automatic 2 Original setting
Day 1 8:30am - 5:30 pm 2 90% 3 Manual trial
Day 2 8:30am - 5:30 pm 2 80% 3 Manual trial
Day 3 8:30am - 5:30 pm 2 70% 3 Manual trial
Actions
• Modification of the VSD fan setting• Manual control for N+1 arrangement• Notice to the loading conditions (similar
testing conditions)• Three days trials
Technical approach examples
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7th May 8th May 9th May 10th May39
Technical approach examplesChillers Plant Saving
Measure and verification
Actual measured data during the chillers sequencing trials
COP
Baseline
3 days average COP improvement(by measurement )
Approx. 15%
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Common difficulties & solutions
Regular calibration of monitoring/ control sensors / actuators
Better data documentation (BMS data storage and checking)
Fully utilize Energy Management System (Identify key indicator, i.e. COP, by pass flow rate, approach temperature…)
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Ensure data availability, sensor accuracy and understanding plant characteristic
Carry out data analysis based on Engineering knowledge,
Translate to simple house rules for Technicians to follow
Technicians
Engineers
Provide top management supports including authority, resources, time,
investment on monitoring devices/ tools/ trainings, etc.
Owners
Common difficulties & solutions
Thank You