technical guidelines on retro-commissioning · 1. introduction. 5. technical guidelines on retro...

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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1

2

3

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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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1

2

3

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7

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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