Energy Management with the use of an Intelligent Building

Management System

Focus

• Basic Concept of Intelligent Building Management System

• How an intelligent BMS can be applied on Energy Management in large size commercial buildings

Basic Concept of Intelligent Building Management System

• What is BMS? (computer?)

– Instruments

– PC + software

– Network

– Controller

Building Management System(Past, Present, Future)

• Recorder

• Information Technology System (ITS)– data monitoring, implementation & transfer

• Artificial Intelligent System (ATS)– self-learning, diagnosis

What is the duties of BMS ?

• Reporting - information print out

• Monitoring - provide message / signal /alarm

• Prediction - cooling demand, energy

• Control - program, schedule

• Diagnosis - analysis

Information Flow in BMS

• signal• data• graphic• models• program

HOURS 0 1 2 CH.W. Leaving Temp. °C 10 11 11 CH.W. Leaving Temp. SP °C 7 7 7 Evaporator Ref. Pressure kPa 597 604 607 Condenser Ref. Pressure kPa 593 601 603 CH. Water Flow L/S 6.2 -0.7 -4.4 Cond. Water Flow L/S -6.8 -6.8 -6.8 Motor Current % 0 0 0 HV. Average Volt kV -0 -0.1 -0.1 HV. Board Power MWh MWh 4.7 4.7 4.7 Chiller On/Off Status Off Off Off

15C 33C

6.5C

8C

Outdoor temperature

CHWST

Save?

Save?

• Y = mx + c

• y = ao + a1x + a2x2

Advantages in using BMS in Building Facilities Management

• Operation– Centralize , Program, Automate, Remote– flexible, save operation & maintenance cost

• Maintenance– reactive proactive (monitor, keep checking)– increase services quality level (SQL)

• Applicable to Energy Management

O&M Examples

Operation• ON/OFF equipment

by IR-sensor• Signal - occupants• zoning & scheduling

by BMS program• ON/OFF/reset output• Automation

Maintenance• Fault identification of

VAV boxes• Signal - damper position,

temperature• abnormal data presented

in BMS• Output - message• Manpower saving

Energy Management in Building

(how to use BMS in EM?)

What is Energy Management

Energy Audit

Data Analysis

Identify Energy Saving Opportunities

Implementation

Measurement & verification (M&V)

Evaluation

Energy Management & BMS

• Energy audit

• Data Analysis

• Identify saving

• Implementation

• M&V

• Evaluation

Chiller1 Performance Comparison (Graph 1)

y = -0.0000000304x2 + 0.0005132005x + 3.3493876192

y = -0.0000002091x2 + 0.0018244582x + 0.8680635579

y = 0.0017x - 0.5848y = 0.0008x - 0.7165

0

1

2

3

4

5

6

7

8

0 900 1,800 2,700 3,600 4,500 5,400Output (kW)

Chiller1 COP (before cleaning)

Chiller1 COP (after cleaning)

Chiller1 CTD (before cleaning)

Chiller1 CTD (after cleaning)

HOURS 0 1 2 CH.W. Leaving Temp. °C 10 11 11 CH.W. Leaving Temp. SP °C 7 7 7 Evaporator Ref. Pressure kPa 597 604 607 Condenser Ref. Pressure kPa 593 601 603 CH. Water Flow L/S 6.2 -0.7 -4.4 Cond. Water Flow L/S -6.8 -6.8 -6.8 Motor Current % 0 0 0 HV. Average Volt kV -0 -0.1 -0.1 HV. Board Power MWh MWh 4.7 4.7 4.7 Chiller On/Off Status Off Off Off

Chiller Performance Comparison

y = -0.00000033x2 + 0.00334288x - 3.06269557y = -0.00000034x2 + 0.00361277x - 4.43626851

2.0

2.5

3.0

3.5

4.0

4.5

5.0

5.5

6.0

0 1,000 2,000 3,000 4,000 5,000 6,000

Output(kW)

CO

P

COP (before cleaning)

COP (after cleaning)

Example - 1Chilled Water Supply

Temperature Reset (CityPlaza)

• CHWST - summer 6.5°C ; winter 7.5 °C

• Reset CHWST in according to outdoor condition

Idea

15C 33C

6.5C

8C

Outdoor temperature

CHWST

Save?

Save?

Use of BMS• Data collect & analysis - outdoor

temperature, chiller performance, CHW supply & return temperature

• Algorithm programmed in BMS

• Output - CHW supply temperature reset value

• Verify the energy saving from data recorded in BMS

Investment vs Benefit

Investment• Modify control

logic program in BMS

Benefit• Programmable• predictable and verified• Fully Automatic• negligible additional

investment & maintenance cost

Example 2Free Cooling by Outdoor Air

(Taikoo Place)

• Constant amount of outdoor air intake

• Amount of outdoor air intake in according

to the air temperature between outdoor &

indoor

Idea• Air temperature

outdoor < indoor

extra cooling capacity• More Outdoor Air & Less

Return Air• Cooler intake air before

cooling coil less cooling demand

Indoor airtemperature

temperature

Outdoor airtemperatureprofile

Time (month)

Extra coolingcapacity from OA

Saving incoolingdemand

Cooling demandprofile

Time (month)

Coolingdemand

Control Strategy

• Air temperature

Outdoor < Indoor

• Adjusting the dampers position of outdoor air and return air

-

More return air

Less outdoorair (HOT) Supply air

Fixed damperposition

-

Less return air

More outdoorair (COOL) Supply air

Adjusting damperposition

Investment vs Benefit

Investment

• Motorized damper• program in BMS

Benefit

• Estimated saving HK$120,000/yr

• Negligible additional maintenance cost

• Fully automation

Example 3Carpark Ventilation Control Based on Actual CO level

(CityPlaza)

• Any air quality problem?

• Fans are operated in 2 speed

– High speed 7:00 – 23:00

– Low speed 23:00 – tomorrow 7:00

Idea

• Installation of CO monitoring system

• BMS used to trend the CO conc. profile

• EPD requirement vs actual CO conc. (gap)

• Possibility to reduce fan speed

EPD Acceptable level (say10,000

g/m3)

7:00 23:00 Tomorrow 7:00time

Gap

CO conc.

CO conc. Profile

Implementation Strategy(Original & 1st trail)

No. of fanoperate

7:00 tomorrow7:00 23:00

8

4

Original (HK$ 1,670,000)

Weekday (low speed)Weekend (high speed)

No. of fanoperate

7:00 tomorrow7:00 23:00

8

4

1st trail (HK$850 ,000)

Weekday & weekend(low speed)

Implementation Strategy(2nd & 3rd trail)

No. of fanoperate

7:00 tomorrow7:00 23:00

8

4

2nd trail (HK$750,000)

2

Weekday & weekend(low speed)

No. of fanoperate

7:00 tomorrow7:00 23:00

0

4

3rd trail (HK$700,000)

2

4Exhaust fan

Supply fanWeekday & weekend(low speed)

Use of BMS

• Data collect & analysis - CO level

• Fan schedule programmed in BMS

• Output - Fan ON/OFF in high / low speed

Investment vs Benefit

Investment

• Initial cost is HK$560,000

• Maintenance cost is HK$42,000/yr

Benefit

• Estimated annual saving is HK$970,000

• Automation• Health & Acceptable

IAQ level

Example 4

Optimal AHU/PAU Start Up Time in A/C System

Background

• Office Tower A/C hour 08:00-19:00

• AHUs start at 07:00 / 07:30 for pre-cooling

• PAUs start with AHU

• BMS to control the A/C system

• PAU (Fresh Air)– Office hours usually start at 09:00– Delay the PAU starting time?

• AHU (Cooling)– Office space temp. vary with outdoor temp.– Desire the optimum start up time of AHU to

just meet the cool down period?

Idea

Average Outdoor Temp at 08:00

AHU Control Strategy

230C

07:2507:00 07:50Time

280C

180C

Outdoor Temp.

PAU Control Strategy

PAU(09:00)

AHUs(07:00-07:50)

Time

ON

OFF

Outdoor Temp. > 18 0C DB

PAU/AHUs(07:50)

Time

ON

OFF

Outdoor Temp. 18 0C DB

Use of BMS

• Feedback signal – outdoor temperature

• Programming in BMS

• Output - AHU/PAU start up time

Investment

• Hardware - None

• Software– BMS contractor to write a program to

incorporate into the PAU/AHU control

• Initial cost - HK$11,600.00

Benefit

• Yearly saving about HK$160,000– equivalent to 96,000kg CO2 emission for coal-

fired power generation

• Fully automatic

• No O&M cost

Example 5Optimal Static Pressure Reset in

Variable Air Volume A/C System

2002 Hong Kong Eco-Business Awards

Green Innovative Practice

‘Gold’ Award

CityplazaTaikoo Shing

• Built in 1997

• Grade A office with over 50000m2

• HK BEAM -Excellent rating

Schematic Diagram of VAV System

P - Pressure sensor , D - Control Damper, VSD - Variable speed Drive

VSD

P

P

T

T

VAV BoxesAH U

T

T

T

T

T

T

T

T

D

D

D

D

D

D

D

D

Use of BMS

• Feedback signal – 32 nos VAV damper position

• Programming in BMS

• Output - main duct pressure

Static Pressure Profile

Light LoadAHU On

Investment

• Hardware– added a control unit

• Software– BMS contractor to write a program according

to designed control logic

• Initial cost - HK$69,400.00

Benefit

• Yearly saving is about HK$200,000– equivalent to 120,000kg CO2 emission for coal-

fired power generation

• VAV boxes re-commissioned

• noise reduced at part load

• assist in VAV fault diagnosis

• Fully automatic

Future Development

• Fruitful quality of information

• Web base performance

• Self learning

• fault detection and diagnostic

Thank You!