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 CH.W. Leaving Temp.

CH.W. Leaving Temp. SP Evaporator Ref. Pressure Condenser Ref. Pressure CH. Water Flow Cond. Water Flow Motor Current HV. Average Volt HV. Board Power MWh Chiller On/Off Status CHWST 8  C °C °C kPa kPa L/S L/S 0 10 1 11 2 11 7 7 7 597 604 607 593 601 603 6.2 -0.7 -4.4

-6.8 -6.8 -6.8

0 0 0 % kV MWh -0 -0.1 -0.1

4.7 4.7 4.7

Off Off Off Save?

Save?

6.5

 C • • Y = mx + c y = a o + a 1 x + a 2 x 2 15  C 33  C Outdoor temperature

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 HOURS CH.W. Leaving Temp.

CH.W. Leaving Temp. SP Evaporator Ref. Pressure Condenser Ref. Pressure CH. Water Flow Cond. Water Flow Motor Current HV. Average Volt °C °C kPa kPa L/S L/S % kV 0 10 1 11 2 11 7 7 7 597 604 607 593 601 603 6.2 -0.7 -4.4

-6.8 -6.8 -6.8

0 0 0 -0 -0.1 -0.1

HV. Board Power MWh Chiller On/Off Status MWh Off Off Off 7

2 + 0.0005132005x + 3.3493876192

y = -0.0000002091x

2 + 0.0018244582x + 0.8680635579

6 2 1 0 5 4 3 Chiller1 COP (before cleaning) Chiller1 COP (after cleaning) Chiller1 CTD (before cleaning) Chiller1 CTD (after cleaning) 0 900 1,800 2,700

Output (kW)

3,600 4.0

3.5

3.0

2.5

2.0

Chiller Performance Comparison

6.0

5.5

y = -0.00000033x

2 + 0.00334288x - 3.06269557

y = -0.00000034x

2 + 0.00361277x - 4.43626851

5.0

4.5

COP (before cleaning) COP (after cleaning) 0 1,000 2,000 3,000 4,000 5,000 6,000

Output(kW) y = 0.0017x - 0.5848

y = 0.0008x - 0.7165

4,500 5,400

Example - 1 Chilled Water Supply Temperature Reset (CityPlaza) • CHWST - summer 6.5°C ; winter 7.5 °C • Reset CHWST in according to outdoor condition

Idea CHWST 8  C Save?

6.5

 C 15  C Save?

33  C Outdoor temperature

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 2 Free 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

temperature Cooling demand Extra cooling capacity from OA Outdoor air temperature profile Saving in cooling demand Cooling demand profile Time (month) Indoor air temperature Idea • Air temperature outdoor < indoor  extra cooling capacity • More Outdoor Air & Less Return Air • Cooler intake air before cooling coil  less cooling demand Time (month)

Control Strategy • Air temperature Outdoor < Indoor Less outdoor air (

HOT

) More return air Fixed damper position • Adjusting the dampers position of outdoor air and return air More outdoor air (

COOL

) Less return air Supply air Supply air Adjusting damper position

Investment vs Benefit Investment Benefit • Motorized damper • program in BMS • Estimated saving HK$120,000/yr • Negligible additional maintenance cost • Fully automation

Example 3 Carpark 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 CO conc.

7:00 Gap EPD Acceptable level (say 10,000 m g/m3) CO conc. Profile time 23:00 Tomorrow 7:00

Implementation Strategy (Original & 1 st trail) No. of fan operate Original (HK$ 1,670,000) 8 Weekday (low speed) Weekend (high speed) 4 7:00 23:00 7:00 tomorrow No. of fan operate 8 1 st trail (HK$850 ,000) 4 7:00 Weekday & weekend (low speed) 23:00 7:00 tomorrow

Implementation Strategy (2 nd & 3 rd trail) No. of fan operate 2 nd trail (HK$750,000) 8 4 2 7:00 Weekday & weekend (low speed) 23:00 7:00 tomorrow No. of fan operate 4 0 3 rd trail (HK$700,000) Exhaust fan 4 2 7:00 Supply fan Weekday & weekend (low speed) 23:00 7:00 tomorrow

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) Idea – 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?

Average Outdoor Temp at 08:00

AHU Control Strategy Outdoor Temp.

28 0 C 23 0 C 18 0 C 07:00 07:25 07:50 Time

PAU Control Strategy ON Outdoor Temp. > 18 0 C DB ON Outdoor Temp.  18 0 C DB OFF AHUs (07:00-07:50) PAU (09:00) Time OFF PAU/AHUs (07:50) Time

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 CO 2 fired power generation emission for coal • Fully automatic • No O&M cost

Example 5 Optimal Static Pressure Reset in Variable Air Volume A/C System

2002 Hong Kong Eco-Business Awards

Green Innovative Practice ‘Gold’ Award

Cityplaza Taikoo Shing • Built in 1997 • Grade A office with over 50000m 2 • HK BEAM Excellent rating

Schematic Diagram of VAV System AHU VSD

P

D D

T T

VAV Boxes D D

T T T

D

T

D

T

D D

T T T P

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

Use of BMS • Feedback signal – 32 nos VAV damper position • Programming in BMS • Output - main duct pressure

Static Pressure Profile Light Load AHU 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 CO 2 fired power generation emission for coal • 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!