Building Energy Saving through Life-Cycle

Optimization, Commissioning and Diagnosis

– Experiences in International Commerce

Center (ICC) of Hong Kong Shengwei Wang

Chair Professor of Building Services Engineering

Building Energy and Automation Research Laboratory, Institute of Sustainable Urban Development/Department of Building Services Engineering

The Hong Kong Polytechnic University

beswwang@polyu.edu.hk

1

SinBerBEST Annual Meeting, 09-10, Jan, 2013, Singapore

Outline of Presentation

• Basic approaches for building energy saving

• Life-cycle diagnosis/commissioning and optimization

• Technologies and deliverables

• Research areas and expertise

• Application Case 1 – ICC

• Application Case 2 – A Hotel Building

• Recent existing Building Energy Projects

2

Basic Approaches for Energy Efficient Buildings

• Reduced heating/cooling loads

– Building envelope design, passive design, etc.

• Use of energy efficient building systems and technologies

• Optimization of system and technology integration, operation and control

– Life-cycle commissioning, design optimization, control optimization, etc.

3

Team’s Research Objectives and Applicable

Deliverables

• Life-cycle Diagnosis/Commissioning

and Optimization

4

Objectives of Diagnosis/Commissioning and Optimization

Objective of Diagnosis/Commissioning

• To ensure the operation performance of the systems delivered meet the design intent.

Objective of optimization

• To push the operation performance of the systems delivered to approach the best, often exceed the design intent.

5

Steps towards Energy Efficient Buildings

Make designs proper and correct

Optimize designs and selections

Construct/install systems correctly

Ensure systems operate as good as intent

Push systems approach the best

Design Stage

Construction Stage

Operation Stage

and T&C Stage

6

Contents of Diagnosis/Commissioning

and Optimization

7

Content of Diagnosis/commissioning

• Design configuration; • Component selection and sizing; • Installation; • (Monitoring and control) instrumentation; • Test and commissioning; • Operation and control; • Maintenance, etc.

Deviations of performances of a deliverable from its design

intent come from different sources at different stages, diagnosis

and commissioning should cover different stages:

8

Design Intent vs Deliverable

Content of Optimization ___________________________________________________________________________

Optimization of HVAC&R systems

Optimization could be performed at different stages allowing the

systems to provide expected quality of services (comfort and health

environment) with reduced (minimum) energy consumption by

means of:

• Optimizing design configuration;

• Optimizing selection and sizing;

• Optimizing (monitoring/control) instrumentation;

• Optimal operation and control, etc.

9

Technologies and Deliverables

10

Examples of Technologies • Building Performance Quick Evaluation and Diagnostic Tool

• Detailed Evaluation and Diagnostic Tool for A/C and BA systems

• Building System Online Performance Simulation Test Platform

• Existing Building Commissioning and Upgrading Assessment Tool

• BA Control and Diagnosis Strategy Online Test Platform

• Package of Online Optimal and Energy Efficient Control and Fault

Diagnosis Strategies

• Intelligent Building Integration and management Platform-IBmanager

11

Both new building development and Existing

Building Energy Saving are the targets.

Building Life-cycle Diagnosis, Commissioning and Optimization

- International Commerce Centre (ICC)

12

Our Roles in ICC Project

Independent Energy Consultant (Independent Commissioning Agent)

To Develop the HVAC Energy Optimal Control System

490 m

118 F

13

Virtual Building System – Dynamic simulation platform of the complex HVACR system

Chiller One

TYPE 23

Chiller Four

TYPE 23

Chiller Six

TYPE 23

Chiller Two

TYPE 23

Chiller Three

TYPE 23

Chiller Five

TYPE 23

CTA Three

TYPE 1

CTB One

TYPE 2

CTA Five

TYPE 1

CTA Two

TYPE 1

CTA Four

TYPE 1

CTB Two

TYPE 2

CTA One

TYPE 1

CTB Five

TYPE 2

CTB Four

TYPE 2

CTB Three

TYPE 2

CTA Six

TYPE 1

Cooling tower controller

TYPE 3&54&55

Mixing after chiller condensers

TYPE 4

Mixing after cooling towers

TYPE 5

Data Reader

TYPE 9

Chiller sequence controller

TYPE 50

Mixing & Bypass

TYPE 67

Return pipe

TYPE 31 Supply pipe

TYPE 31

Pump & network

TYPE 12

AHUs

TYPE 63

PID control

TYPE 42

Pump sequence

TYPE 39

HX modeling&mixingTYPE 41

HX sequence

TYPE 39

PID control

TYPE 43

Tao,i

Load & status of AHUs

TYPE 49

Pump & network

TYPE 13

AHUs

TYPE 21

PD optimizerTYPE 7

PID control

TYPE 20

Pump sequence

TYPE 39

PID control

TYPE 43

Tao,i

VPi

PDset

Pump & network

TYPE 14

PID control

TYPE 43

PID control

TYPE 43

Mixing

TYPE 48

Tw,out

HX modeling&mixing TYPE 36

HX sequence

TYPE 39

Pump & network

TYPE 17

AHUs

TYPE 63

PID control

TYPE 42

Pump sequence

TYPE 39

PID control

TYPE 43

Tao,i

Pump & network

TYPE 15

PID control

TYPE 43

PID control

TYPE 43

Mixing & bypass

TYPE 19

Tw,o

ut

Load & status of AHUs

TYPE 35

Pump & network

TYPE 18

AHUs

TYPE 63

PID control

TYPE 42

PID control

TYPE 43

Tao,i

HX modeling&mixing TYPE 37

HX sequence

TYPE 39

Pump & network

TYPE 16

PID control

TYPE 43

PID control

TYPE 43Mixing & bypass

TYPE 45

PD optimizerTYPE 6

VPi

PDset

PD optimizerTYPE 8

Pump sequence

TYPE 39

PDset

PD optimizerTYPE 62

PDset

Mixing

TYPE 47

Mixing

TYPE 47

Tw,su

p

Mw,i

On/

Off

of

AH

Us

Mw

& P

Dm

eas

Npu

Freq

On/

Off

of

AH

Us

Mw,i

Mw

& P

Dm

eas

Freq

Npu

Nhx

Tw,su

p

Tw,in &Mw

Tw,su

p

Mw,set

Mw,measFreq

Mw,i

VPi

Npu

Freq

VPi

Mw,i

Freq

Npu

Mw

& P

Dm

eas

Nhx

Mw

Tw,sup&MwMw,set

Mw,measFreqNhx

Load

Nhx

Nhx

Tw,su

p

Tw,out

Ma,

i&Ta

,inMa,i&Ta,in

Ma,i&Ta,in

On/Off of AHUs

On/Off of AHUsOn/Off of AHUs

Mw & Tw,rtn Mw & Tw,rtn

On/Off of AHUs Ma,i&Ta,in

On/

Off

of

AH

Us

On/Off of AHUs

Load

Tw,su

pTw

,rtn

& M

w

Tw,rtn & Mw

Tw,in

Mw

& T

w,in

Tw,sup & MwMw & Tw,rtn

Nhx

Mw

Mw

,&w

,in

Tw,rt

n&

Mw

Mw,measFreq

Mw,set

Mw

Nch On/Off On/Off On/Off On/Off On/Off On/Off

Tw,ch,out Tw,ch,out Tw,ch,out Tw,ch,out Tw,ch,out Tw,ch,out

Tsup

Tsup

Mw

,tot&

Trt

n

Nch Tw,cd,out Tw,cd,out Tw,cd,out Tw,cd,out Tw,cd,out Tw,cd,out

Tw,cd,in

Mw,tot&Tw,ct,inTw,cd,outOn/Off,i&Freq,i

Zone 2

Zone 1Zone 3&4

NumberN:

Valve positionVP:

Pressure differentialPD:

FrequencyFreq:

Cooling loadLoad:

Water or air flow rateM:

TemperatureT:

Component type numberTYPE XX:

NumberN:

Valve positionVP:

Pressure differentialPD:

FrequencyFreq:

Cooling loadLoad:

Water or air flow rateM:

TemperatureT:

Component type numberTYPE XX:

Supplysup:Heat exchangerhx:

wb:

ct:

cd:

rtn:

in:

ao:

meas:

w:

Subscript

Wet-bulb

Cooling tower

Condenser

Return

Inlet

Air outlet

Measurement

Water

Set-pointset:

Chillerch:

Dry-bulbdb:

Outletout:

Pumppu:

Totaltot:

Individuali:

Aira:

Supplysup:Heat exchangerhx:

wb:

ct:

cd:

rtn:

in:

ao:

meas:

w:

Subscript

Wet-bulb

Cooling tower

Condenser

Return

Inlet

Air outlet

Measurement

Water

Set-pointset:

Chillerch:

Dry-bulbdb:

Outletout:

Pumppu:

Totaltot:

Individuali:

Aira:

Tw,out & Mw Tw,out & Mw Tw,out & Mw Tw,out & MwTw,out & MwTw,out & MwTw,out & Mw Tw,out & MwTw,out & Mw Tw,out & Mw

Mw,tot&Tw,ct,out

Pump sequence

TYPE 39NpuMw

Pump sequence

TYPE 39

Npu

Mw

Mixing

TYPE 60

Tw,rtn & Mw,tot

Twb&

Tdb

Tw,out,i

Mixing

TYPE 61

Mw,tot & Tw,rtn

Zone airflow rates

Zone 1

Zone 2 Zones 3&4

Virtual Building

System Simulated

BA & Strategies

(updated throughout the entire

process)

• Verifying/improving the system configuration and component selection including the chiller system, water system (primary/secondary system), heat rejection system (cooling towers), fresh air system etc.

• Verifying and improving the metering system for proper local control, and the original proposed control logics at the design stage.

• Proposal of additional metering system for implementing supervisory control and diagnosis strategies and related facilities for implementing these strategies

Commissioning at Design Stage

Design commissioning mainly concerns the future

operation and control performance of HVAC systems,

including:

An Example of Diagnosis and Optimization at Design Stage

HX-42 HX-42 HX-42 HX-42 HX-42 HX-42 HX-42

(S-B

)

FROM OFFICE FLOORS (43-77)

TO OFFICE FLOORS (43-77)

(S-B

)

HX-78HX-78HX-78

TO OFFICE FLOORSS (79-98)

FROM OFFICE FLOORS (79-98)

(S-B

)(S

-B)

SCHWP-42-01 to 03SCHWP-42-04 to 06

SCHWP-78-01 to 03

SCHWP-06-06 to 09

To Z

on

e 3&

4

Fro

m Z

on

e 3&

4

Flow meter

Bypass valve

EVAPORATOR EVAPORATOR EVAPORATOR EVAPORATOREVAPORATOREVAPORAROR

WCC-06a-01

(2040 Ton)

PCHWP-06-01

FROM OFFICCE FLOORS(7-41)

TO OFFICE FLOORS(7-41)

HX-42

PCHWP-06-02 PCHWP-06-03 PCHWP-06-04 PCHWP-06-05 PCHWP-06-06

WCC-06a-02

(2040 Ton)

WCC-06a-04

(2040 Ton)WCC-06a-03

(2040 Ton)

WCC-06a-05

(2040 Ton)WCC-06a-06

(2040 Ton)

CDWP-06-01 CDWP-06-02 CDWP-06-04CDWP-06-03 CDWP-06-05 CDWP-06-06

A

F

D

CA

B

E

B

D

C

E

F

Secondary water circuit for Zone 1

Secondary water circuit for Zone 2

Secondary water circuit for Zone

3 and Zone 4

Primary water circuit

Chiller circuit

Cooling water circuit

(S-B

)

FROM PODIUM & BASEMENT

TO PODIUM & BASEMENT

HX-06

(S-B

)(S

-B)

(S-B

)

FROM OFFICE FLOORS (43-77)

TO OFFICE FLOORS (43-77)

(S-B

)

CONDENSER CONDENSER CONDENSER CONDENSER CONDENSER CONDENSER

HX-78HX-78HX-78

TO OFFICE FLOORSS (79-98)

FROM OFFICE FLOORS (79-98)

(S-B

)(S

-B)

SCHWP-42-01 to 03SCHWP-42-04 to 06

SCHWP-78-01 to 03

PCHWP-78-03PCHWP-78-01 PCHWP-78-02

PCHWP-42-01 PCHWP-42-02 PCHWP-42-03 PCHWP-42-04 PCHWP-42-05 PCHWP-42-06 PCHWP-42-07

SCHWP-06-06 to 09

SCHWP-06-03 to 05

SCHWP-06-01 to 02

SCHWP-06-10 to 12

To cooling towersFrom cooling towers

HX-42 HX-42 HX-42 HX-42 HX-42 HX-42

HX-06

Original System Revised System

System Design Verification and Optimization Secondary water loop systems of 3rd/4th zones

Primary pumps are omitted

Comparison between Two systems

0

200

400

600

800

1000

1200

1400

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

Time (h )

Pu

mp

pow

er (

kW)

Original design

Alternative design

Typical sunny-summer day

Annual Pump Energy Saving is 1M kWh/水泵年节能量为1百万kWh

Optimal control strategies for central air-conditioning systems

Chiller sequence, optimal start

Optimal chiller sequence - based on a more accurate cooling load

prediction using data fusion method, and considering demand

limiting

Adaptive online strategy for optimal start - based on simplified sub-

system dynamic models

Ventilation strategy for multi-zone air-conditioning system

Optimal ventilation control strategy - based on ventilation needs of

individual zones and the energy benefits of fresh air intake

Peak demand limiting and overall electricity cost

management

19

Chilled water system optimization

Optimal pressure differential set point reset strategy

Optimal pump sequence logic

Optimal heat exchanger sequence logic

Optimal control strategy for pumps in the cold water side of heat

exchangers

Optimal chilled water supply temperature set-point reset strategy

Cooling water system optimization

Optimal condenser inlet water temperature set point reset strategy

Optimal cooling tower sequence

Optimal control strategies for central air-conditioning systems

20

From cooling source

HX

HX

Temperature controller

Differential pressure controller

Temperature

set-pointPressure

differential set-point

To coolingsource

Secondary side of HX Primary side of HX

Temperature controller

Temperature

set-point

MM

ΔP

TT

TT

To terminal

units

From terminal units

Modulating

valves

MM

HX

HX

TT TM

Temperature controller

Water flowcontroller

Temperature

set-point

Water flow

set-point

To terminal

units

From terminal units

Secondary side of HX Primary side of HX

TM

From cooling source

To coolingsource

Original implemented strategy – differential pressure control and by resorting to the modulating valve

Revised strategy – cascade controller without using any modulating valve

Optimal Control of Variable Speed Pumps

Speed control of pumps distributing water to heat exchangers

21

Site practically tests show that the proposed strategy can provide stable and reliable control. Compared to original implemented strategy, about 22.0% savings for pumps before heat exchangers in Zone 1 was achieved.

Energy consumption (kWh)

Pumps Number

(standby) Original

strategy

(kWh)

Alternative

Strategy

(kWh)

Saving

(kWh)

Primary pumps in Zone 1 1(1) 528,008 456,132 71,876

Primary pumps for Zones 3&4 3(1) 921,235 795,830 125,405

Primary pumps in Zone 4 2(1) 401,008 346,420 54,588

Total saving of the primary pumps 251,869

Energy saving of primary pumps before

heat exchanges due to the use of

PolyU strategy is about 250,000 kWh.

Performance test and evaluation

Due to the low load of Zone 1 in ICC at current stage, a simulation test of annual energy savings by using PolyU strategy is performed

22

Visible Plume Abatement

23

Visible Plume

24

At first-level warning, increase airflow rate by 20% when

plume potential is marginal

At second-level warning, increase airflow by 40% when

plume potential is high

Start heating using heat pumps when visual plume is

observed

Decision

maker

Platform for predicting

plume occurring possibility

Normal operation when there is no predicted plume

occurs

Operating Condition Power Consumption

Cooling

Water

Temp Set-

point

Cooling

Tower

Number

Cooling

Tower

Freq

Chiller

Power

Cooling

Tower

Power

Total

Power Difference

Operation modes

°C - Hz kW kW kW kW %

Reference 22.7 3 26.51 856.2 59.1 915.35 -- --

First-level warning 21.3 3 30.74 836.2 93.0 929.2 14.0 1.5

Second-level warming 20.1 3 35.52 819.9 145.9 965.8 50.6 5.5

Using heat pumps 22.7 3CT+1HP 26.51 856.2 59.1 1215.2 300 32.8

Visible Plume Abatement

Additional energy consumption for plume control could

be reduced from 32.8% to 5.5% or 1.5% at low Load

25

Chiller Plant Sequencing Control

of Enhanced Robustness using

Data Fusion Technique

26

Cooling Load Measurement based on Data-Fusion

Cooling load measurement

Direct measurement of building cooling load

Qdm = cpwρwMw(Tw,rtn-Tw,sup)

cpw is the water specific thermal capacity; ρw is the water density;

Mw is water flow rate; Tw,rtn,Tw,sup are chilled water return/supply

temp.

Indirect measurement of building cooling load

Qim = f(Pcom,Tcd,Tev)

Pcom is chiller power consumption; Tcd,Tev are chiller

condensing/evaporating temperatures

27

Robust building cooling load measurement technique Based on Data Fusion

Data fusion to merge “Direct measurement” and “Indirect

measurement” improving the accuracy and reliability of building

cooling load measurement

Chiller 1 Chiller n

Central Chilling Plant

Chiller

Model 1

Direct Load

measurement

Data Fusion

Engine

+

Wch,n,Tev,n,Tcd,n

Tsup Mw

Trtn

Qdm

Qin,1 Qin,n

Qload (Fused cooling load)

rload (Degree of confidence)

…

Advanced soft

measurement system

Chiller

Model n

Wch,1,Tev,1,Tcd,1

28

High degree of confidence => Accurate and relatively aggressive control

Low degree of confidence => Safe control and warning

for maintenance check

Medium degree of confidence => Less aggressive and

safer control

Robust Chiller Sequencing Control Based on Enhanced

Cooling Load Measurement Technique

29

Summary of Energy Benefits

• 1,000,000 kWh energy consumption is saved due to the modification on the secondary water loops of Zone 3 & 4

• 2,360,000 kWh , (about 5.1% of annual energy consumption of chillers and cooling towers) of the cooling system can be saving due to the change from single speed to variable speed using VFD

• 607,000 kWh , (about 2.8% of annual energy consumption of chillers and cooling towers) of the cooling system will be wasted

when the lowest frequency is limited at 37 Hz

• 3, 500,000 kWh (about 7%) of the total energy consumption of HVAC system) can be saved using PolyU control strategies based on the original design

Saving by Control Optimization – compared with the

case when the HVAC system operates correctly as the

original design intent. 3.5M per year

Saving by Commissioning (Improving the system configuration and selection) – compared with the

original design. About 3.5 M per year

The annual total energy

saving is about 7.0M kWh !

30

Contributions in supporting ICC building in getting

HK-BEAM Platinum Certificate

Annual Energy Use Reduction By 14.6% to get extra 2 credits

Peak Demand Reduction By 26.9% to get extra 2 credits

Optimal Control Strategies “Innovation” for extra 1 credits

Grade Overall

Performance

Platinum 75% Excellent

Gold 65% Very Good

Silver 55% Good

Bronze 40% Above average

The overall assessment grade is based

on the percentage of applicable credits

(about 145) gained in 5 categories: site

aspects ， material aspects ， energy

use，water use , and IAQ (vision 4/04 ).

Gold

72.7%）

5 credits (3.5%)

Platinum

76.2%)

H V

A C

A New Hotel Development in Sheung Wan

(Holiday Inn Express)

Independent Energy Consultant (Independent Commissioning Agent)

To Develop the HVAC Energy Optimal Control System

33

Summary of Energy Benefits

Saving by Commissioning (Improving the system configuration and

selection) and Control Optimization – compared with the case

when the HVAC system operates correctly as the

original design intent. 20% saved annually

34