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BUILDING AUTOMATION AND CONTROLSYSTEMS

SECTION VSECTION V

WWHATHAT WWILLILL WWEE CCOVEROVER ?? ControlsControls

Basic Types Inputs & Outputs Technologies

Pneumatic Electric DDC

TerminologyPID C t l PID Controls

Review Building Automation Systems for Energy Building Automation Systems for Energy

ManagementManagement Basic Functions Programs Review

Section V - 2

BBASICASIC TTYPESYPES

Manual Manual SwitchesDimmers

Open Loop AutomaticOpen Loop AutomaticOpen Loop AutomaticOpen Loop AutomaticTimer

Closed Loop AutomaticClosed Loop AutomaticThermostatHumidistatDimmable Ballast w/Photosensor

Section V - 3

BASIC FEEDBACK CONTROL SYSTEM

SET POINT RC

CONTROLLER

ACTUATOR

T

CONTROLLEDDEVICE

SENSOR

AIR FLOW

HEATING COIL

Section V - 4

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BBASICASIC TTYPESYPES

Two Position Two Position The system is either OFF or ON (gas furnace). Accomplished with a relay whose contacts are either

open or closed, or a valve whose stem position is either open or closed.

Proportional Proportional A variation from the set point produces a proportional

movement in the actuator. Pneumatic controls vary the air pressure. Electric controls use a potentiometer (a type of

variable resistor).

Section V - 5

BBASICASIC IINPUTSNPUTS & O& OUTPUTSUTPUTS

Binary or Digital (D)Binary or Digital (D) Signal with two states or positions which can be

incremental (on-off, day-night, open-closed, occupied-unoccupied, series of 1’s & 0’s)

Analog (A)Analog (A) Signal can be monitored or controlled through a

range of positions or values (0 to 50o C, 20 to 35 kPa, 0 to 10 VDC,4 to 20 milliamps)

Section V - 6

Input ExamplesInput ExamplesAnalogAnalog DigitalDigital

Duct Smoke DetectorDigital Input

LANDIS & GYR

Outside Air Temp. SensorAnalog Input

Low Temp. DetectorDigital Input

End SwitchDigital Input

Room Temperature SensorAnalog Input

High Pressure DetectorDigital Input

Smoke Detector

Section V - 7

Input PointsTemperature Relative HumidityFlow PressureStatus or Proof Air Quality

AIAI

AI / DIAI / DIAI / DIAI / DI

AIAIAIAIAIAI

Inputs & OutputsInputs & Outputs

Output PointsMotors for Pumps / Fans ValvesLights DampersVariable Speed Drives Lighting Contactors

(or digital)

DODO AOAO

DODODODO AOAO

AOAO

Section V - 8

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1.VFD Start/Stop

2.VFD Speed Signal

DOAO

Variable Air Volume Variable Air Volume

Inputs & OutputsInputs & Outputs

5.Static Press

4.High Static Cutout

3.Air Flow AIDI AI

SystemSystem

Section V - 9

BBASICASIC TTECHNOLOGIESECHNOLOGIES

PneumaticPneumatic

ElectricElectric

Direct Digital Control (DDC)Direct Digital Control (DDC)

Section V - 10

PPNEUMATICNEUMATIC CCONTROLSONTROLS Use clean, dry, oil-free compressed aircompressed air to operate the control system. Have been used in many HVAC applications.

M ain A ir L ine

Branch A ir L ine

HC

O utside A ir

Supply A ir Sensor

H eatingCoil

Supply Fan

H ot W aterSupply

Air Com pressorController

A nalog S ignal

H ot W ater V alve

Section V - 11

PPNEUMATICNEUMATIC CCONTROLSONTROLS

AdvantagesAdvantages Are well understood by many designers and most

maintenance people. Are inherently proportional and very reliable. Were relatively inexpensive in the past.

DisadvantagesDisadvantages Not very precise. Typically required frequent calibration. Pneumatic control algorithms are hard to change.

(typically pre-set by manufacturer)

Section V - 12

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EELECTRICLECTRIC CCONTROLSONTROLS

Can be analog electric or electronic controls. Use a variable, but continuous, electrical voltage or electrical voltage or

currentcurrent to operate the control system. Transmit signals

quickly and accurately.

Section V - 13

EELECTRICLECTRIC CCONTROLSONTROLS

AdvantagesAdvantages Can be very accurate and very stable. Do not require field calibration, and are drift-free, if

good quality sensors are used. Relatively easy to implement proportional plus

integral (PI) control electronically. g ( ) y

DisadvantagesDisadvantages Difficult to interchange parts easily because of the

many different systems. Do not interface directly with our digital computers

Section V - 14

DDIRECTIRECT DDIGITALIGITAL CCONTROLSONTROLS Use electrical pulseselectrical pulses to send signals. Interface directly with microprocessors, directly &/or via the

internet using TCP/IP.

Section V - 15

DDIRECTIRECT DDIGITALIGITAL CCONTROLSONTROLS

AdvantagesAdvantages Algorithms can be adjusted relatively easily after

installation Precise No controller drift, recalibration is normally not

necessary Cost effective (similar to electronics market) Cost effective (similar to electronics market)

DisadvantagesDisadvantages Possibly not well understood by O&M staff Different communication protocols, interface

standards, and internal logic are typically complex (BACNET-ASHRAE 135-2008; and Lonworks – LonmarkCorporation; are both addressing these interface problems)

Section V - 16

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WWEBEB BBASEDASED EENERGYNERGY IINFORMATIONNFORMATIONANDAND CCONTROLONTROL SSYSTEMSYSTEMS

TCP/IP is Transmission Control Protocol/Internet Protocol

Internet Explorer, Netscape Navigator, Mozilla Firefox all take TCP/IP input

Many submeters now have data accumulators that have URL addresses, and send data by TCP/IP over Local Area Networks

This data will come into your PC in standard spread sheet format This data will come into your PC in standard spread sheet format for you to use as you like

You can make charts, graphs, tables, etc in Excel or other common SS programs

You now have your own web based energy information system

And it doesn’t cost you a fortune. Save your money for the really fancy analysis and diagnostic systems that many companies can provide to you

Section V - 17

CCONTROLONTROL AALGORITHMSLGORITHMS

PID Controls P is proportional I is integral D is derivative

Controls are usually P, PI or PIDPID i id d h b f hi PID is considered the best of this group

Newer control algorithms are: Fuzzy logic Learning systems Self-optimizing systems

Section V - 18

PID Controls Loop ResponsePID Controls Loop Response

Section V - 19

Stability Stable if process doesn't show continuing trend away from setpoint or continuous oscillation following an upset in either load or setpoint

Response Time

Time required for PV to reach SP following a step change in mode or setpoint

Overshoot The amount the PV goes beyond the SP following a change in load or setpoint

Loop DefinitionsLoop Definitions

PID ControlsPID Controls

Overshoot

Offset The amount of constant error existing between PV and SP once the process reaches steady state

Settling Time Time required for process to reach steady state following a change in load or setpoint

Steady StateCondition that exists in closed loop system when the control variable (CV) equals a constant value and no oscillation occurs

Section V - 20

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CONTROL MODE PURPOSE ERROR DETECTIONS

PG Reacts to Change Detects SIZE of Error

Summary Of GainsSummary Of Gains

PID ControlsPID Controls

IG Reduces/Eliminates Offset Averages Error over TIME

DG Senses High Rate Load Detects RATE of change of error

biasactiondt

errordDGactiondterror

IGactionerror

PGadjustableCV

*

)(

1000*

1000*

1000)(

Section V - 21

RREVIEWEVIEW::

CCONTROLSONTROLS

Section V - 22

1. List advantages and disadvantages of pneumatic controls.

2. Why is DDC so popular?

3. What does the term “direct acting” mean?

Section V - 23

4. The difference between the setting at which a controller operates to one position and the setting at which it changes to the other is known as the:

A) Throttling range B) OffsetC) Differential D) Control point

5. What is the flow rate of 16°C water through a control valve with a flow coefficient of 0.01 and a pressure difference of 100 kPa?

A) 0.1 LPS B) 0.2 LPSC) 0.6 LPS D) 0.4 LPS

Section V - 24

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BBUILDINGUILDINGAAUTOMATIONUTOMATIONSSYSTEMSYSTEMS

(BAS)(BAS)

Section V - 25

Floor Level Network

Building Level Network

Management Level Network

BAS AnatomyBAS Anatomy

Remote System Access

Remote Alarm Notification

Interoperability with other Buildings/Systems/Networks

Section V - 26

RECOMMENDED GOAL FOR

OPERATION OF NEW BAS’S

Single seat operation for the BAS using a common database for all operational and maintenance data accessible in the facility.

This means that the Maintenance Management S stem and the Energ Management S stem(s) at the System and the Energy Management System(s), at the minimum, must share a common database.

Section V - 27

BBASICASIC FFUNCTIONSUNCTIONS

1.1. Monitoring/SurveillanceMonitoring/Surveillance• Building Conditions• Equipment Status• Utility Submetering• Climatic Data• Fire & Security• Fire & Security

BUILDING

2FacilityHVAC

3EnergyPower

4FactoryPower

5FactoryPower

andLights

6OfficePower

71st

FloorOfficeLights

82nd

FloorOfficeLights

9Computer

RoomPower

and Lights

10Computer

RoomHVAC

11OfficeHVAC

12OfficeRTU-1

13Office

RTU-13

14OfficeRTU-3

15OfficeRTU-4

19CAFE

20FactoryLights

24Air

Compressor

21Energy

MezzanineTest Room

22Elevator

23EnglishLabs

16Factory

RTU

17Factory

RTU

18Factory

RTU

1A. General Service Meter(Utility Meter for Billing)

1B. Electric Heat Meter(Utility Meter for Billing)

Section V - 28

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BBASICASIC FFUNCTIONSUNCTIONS

2.2. Demand LimitingDemand Limiting• Load shedding• Duty cycling

3.3. MaintenanceMaintenance• Remote operation and control of equipment• Generation of maintenance schedules• Diagnosing breakdowns

4.4. Record GenerationRecord Generation• Trends and operation logs• Utility demand profile (“baseline”)• Modification/replacement analysis• Energy conservation documentation

Section V - 29

SSTARTTART--SSTOPTOP OOPTIMIZATIONPTIMIZATIONHow It WorksHow It Works

Start the equipment at the latest possible time Stop at the earliest possible time

ENERGY (KWH)SAVINGS

FROM SSTOENERGY (KWH)

SAVINGSFROM SSTO

DE

MA

ND

(K

W)

0 2018161412108642 22 24

OFF-PEAK$0.0453/KWH

OFF-PEAK$0.0453/KWH

PEAK$0.0759/KWH

OCCUPANCY PARTIALOCC

Section V - 30

CCHILLEDHILLED WWATERATER RRESETESET IntroductionIntroduction

Many buildings’ chilled water setting is designed for the heaviest anticipated cooling load.

Significant cost savings can result from resetting chilled water temperatures in anticipation of cooling load

How It WorksHow It Works When the load, chilled water T, or return chilled water

temperature increases, the chilled water setpoint is lowered, and vice versa

A one degree C increase in CWT makes the chiller about 2% more efficient

You must be able to meet both sensible and latent cooling loads. Also, there may be minimum flow condition on the chiller that limits this change.

Section V - 31

CCONDENSERONDENSER WWATERATER RRESETESET

The same idea can be used on the other side of the chiller by reducing the temperature of the cooling water from the cooling tower.

For every one degree C reduction in the y gtemperature of the cooling water, the chiller efficiency goes up about 1.5 %.

Be careful with older chillers, since they can not take too cold cooling water without developing head pressure problems.

Section V - 32

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SSUPPLYUPPLY AAIRIR RRESETESET

Supply Air Reset Based on LoadSupply Air Reset Based on Load A good rule of thumb provides for a supply air

temperature reset for one-fourth the difference between the supply design temperature and the design space temperature

Savings Calculation Savings Calculation

Where: Lowest Desired Temp is the temperature of the coolest room Supply Air Design is the current temperature of Supply Air

DesignAirSupplyDesignAirSupplyTempDesiredLowest

SAR

4

Section V - 33

SSTATICTATIC PPRESSURERESSURE RRESETESET How It WorksHow It Works

The DDC system monitors the VAV static pressure and lowers the pressure until only one damper is completely open

The Static Pressure and VFD control sensors must be located on the same DDC control panel

40% 50% 60%

7 5 % 1 0 0 % 7 0 %

Section V - 34

SSTATICTATIC PPRESSURERESSURE RRESETSESETS•• Proof of PerformanceProof of Performance

– Operating the fan with zero airflow wastes energy– Modulating fan speed based on damper position reduces

fan usage and saves energy

2.5w.g

.)

5

2.0

1.5

1.0

0.5

0.00 50% 100%

Sta

tic

Pre

ssu

re (

in. w

Demand

No Reset

Reset

Energy Savings

Section V - 35

EECONOMIZERCONOMIZER

•• How It WorksHow It Works– Reduce cooling & heating energy by optimizing mixed air temp– As the outside air allows, the outdoor air damper opens more– Free heating/cooling occurs when occupant comfort is maintained

without using mechanical heating or cooling

E c o n o m iz e rS w itc h P o in t

Ou td

o o r Air

D amp e r

He a tin g -C

o il V a lv e

Co o lin

g -Co i l

V a lve

O u ts id e A ir T e m p e ra tu re (ºF )

M e c h a n ic a l H e a tin g F r e e C o o lin g M e c h a n ic a l C o o lin g

5 0 7 0

0

1 0 0

6 5

M A M

% O

pen

Section V - 36

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DDEMANDEMAND CCONTROLONTROL VVENTILATIONENTILATION

How It WorksHow It Works DCV provides just the right amount of outside needed by

occupants Modulates ventilation to main target cfm/person

ventilation based on actual occupancy Less than 700 ppm above outside CO2 concentration

1 0 0 %

or city

8 0 %

6 0 %

4 0 %

2 0 %Per

cent

Bui

ldin

g O

ccup

ancy

o

Per

cent

Tot

al V

entil

atio

n C

apac

B u ild in g O c c u p a n c y /D e m a n dV e n tila tio n C o n tro l

E n e rg y S a v in g s w ithD e m a n d C o n tro lle d V e n tila tio n

O cc u p a n c y P e rio dE n e rg y C o st w ithD e m a n d C o n tro lle d V e n tila tio n

4 :0 0 6 :0 0 8 :0 0 1 0 :0 0 1 2 :0 0 1 4 :0 0 1 6 :0 0 1 8 :0 0 2 0 :0 0 2 2 :0 0 2 4 :0 0

Section V - 37

HHOTOT WWATERATER RRESETESET -- HHOWOW IITT WWORKSORKS

Hot water boilers are very efficient at partial load Distribution losses are less when temperature is reduced Hot water reset conserves energy by reducing the boiler’s

operating temperature Hot water reset reduces thermal shock because it does not

involve drastic temperature fluctuations To minimize flue gas corrosion do not reset lower than 60 ºC To minimize flue gas corrosion, do not reset lower than 60 C

Section V - 38

HHOTOT WWATERATER RRESETESETProof of PerformanceProof of Performance

Maintaining 180ºF (82 ºC)water temperature forces the heating valves to cycle open and closed

160

150

140

170

180Hot Water Supply (ºF)

130

80

70

60

50

40

30

20

10

0

7:0

0

8:00

9:0

0

10:

00

11:

00

12:

00

13:0

0

14:0

0

15:

00

16:

00

17:

00

18:0

0

19:0

0

Outside Air Temp (ºF)

Valve Position (% open)

Section V - 39

HHOTOT WWATERATER RRESETESET

Proof of PerformanceProof of Performance Resetting the hot water temperature allows heating

valves to operate in more efficient mid-actuation positions

160

150

140

170

180

Hot Water Supply (ºF)

Theoretical Potential Savings

130

80

70

60

50

40

30

20

10

0

7:0

0

8:00

9:0

0

10:

00

11:

00

12:

00

13:

00

14:0

0

15:

00

16:

00

17:

00

18:

00

19:

00

Outside Air Temp (ºF)

Valve Position (% open)

Section V - 40

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RREVIEWEVIEW::

BASBAS

Section V - 41

RREVIEWEVIEW: BAS/EMS: BAS/EMS

1. Distinguish between analog and digital control.

2. Devices using 4-20 mA current loops are using digital data transmission.(A) True (B) False

Section V - 42

3. A facility is heated by fan coil units using hot water pumped from a central boiler system. List some EMS controls that could reduce the facility energy costs.

4. List some maintenance aids that could be provided by an EMS.

Section V - 43

5. An optimum start device is a control function that:(A) Shuts off the outside ventilation air during start up of the building.

(B) Shuts off equipment for duty cycling purpose.

(C) Senses outdoor and indoor temperatures to ( ) pdetermine the minimum time needed to heat up or cool down a building.

(D) Compares the enthalpy of outdoor and return air and determines the optimum mix of the two streams.

Section V - 44

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Control BasicsControl BasicsControl Functions & TerminologyControl Functions & TerminologyBAS/EMS BasicsBAS/EMS BasicsBAS/EMS Functions & ProgramsBAS/EMS Functions & Programs

Overall RecapOverall Recap

Section V - 45

APPENDIX

Section V - 46

CCONTROLONTROL TTERMINOLOGYERMINOLOGY Set PointSet Point – The value of the controlled variable

that is to be maintained. Control PointControl Point - The actual value of the controlled

variable (temperature, pressure, flow, etc,). OffsetOffset - The difference between the set point and

the control point or the actual value of the controlled variable. (This is sometimes called drift, deviation, or control point shift.), p f )

Direct Acting ControllerDirect Acting Controller – A controller for which an increase in the level of the sensor signal (temperature, pressure, etc,) results in an increase in the level of the controller output.

Modulating ControllerModulating Controller – A type of controller for which the output can vary infinitely over the range of the controller.

Section V - 47

DifferentialDifferential – For a two-position controller it is the difference between the setting at which the controller operates at one position and the setting at which it changes to the other position. (All two-position controller need a differential to prevent “hunting,” or rapid cycling. For a thermostat, the differential is expressed in degrees of temperature.)

DeadDead--BandBand – The range over which the output of the controller remains constant as the input varies the controller remains constant as the input varies, with the output changing only in response to an input outside the differential range.

Throttling RangeThrottling Range – The amount of change in the controlled variable required to run the actuator of the controlled device from one end of its stroke to the other end. (If the actual value of the controlled variable lies within the throttling range of the controller, it is said to be in control. When it exceeds the throttling range it is said to be out of control.)

Section V - 48

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GainGain – The ratio of the output of the controller to the input. In a pneumatic temperature controller, for example, the gain would be expressed as:

gain = Controller Output (kPa)Throttling Range (degrees)

Linear Percentage ValveLinear Percentage Valve A valve with a plug Linear Percentage ValveLinear Percentage Valve – A valve with a plug shaped so that the flow varies directly with the lift.

Equal Percentage ValveEqual Percentage Valve – A valve with a plug shaped so the flow varies as the square root of the lift.

Flow (LPS) = Cv x √∆P

Section V - 49

WWATERATER FFLOWLOW TTHROUGHHROUGH VVALVESALVES

Section V - 50

OOTHERTHER EMS PEMS PROGRAMSROGRAMS

1.1. Scheduled Start/StopScheduled Start/Stop – Starting and stopping equipment based upon the time of day, and the day of the week.

2.2. Duty CyclingDuty Cycling – Shutting down equipment for predetermined short periods of time during normal operating hours.p g

3.3. Demand LimitingDemand Limiting – Temporarily shedding electrical loads to prevent exceeding a peak value.

4.4. Unoccupied SetbackUnoccupied Setback – Lowering the space heating setpoint or raising the space cooling setpoint during unoccupied hours.

Section V - 51

5.5. Warm Up/Cool Down Ventilation & Warm Up/Cool Down Ventilation & RecirculationRecirculation – Controls operation of the OA dampers when the introduction of OA would impose an additional thermal load during warm-up or cool-down cycles prior to occupancy of a building.

6.6. Hot Deck/Cold Deck Temperature ResetHot Deck/Cold Deck Temperature Reset -Selects the zone/area with the greater heating and cooling requirements, and establishes the minimum hot and cold deck temperature differential which will meet the requirements.

77 Steam Boiler OptimizationSteam Boiler Optimization Implemented in 7.7. Steam Boiler OptimizationSteam Boiler Optimization – Implemented in heating plants with multiple boilers. Boiler plant optimization is accomplishes through the selection of the most efficient boiler to satisfy the space temperature requirements during the building occupied period.

8.8. Reheat Coil/ResetReheat Coil/Reset – Selects the zone/area with the greatest need for reheat, and establishes the minimum temperature of the heating hot water so that it is just hot enough to meet the reheat needs for that time period.

Section V - 52

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9.9. Chiller &/or Boiler OptimizationChiller &/or Boiler Optimization – For facilities with multiple chillers &/or boilers, the most efficient chiller(s) &/or boiler(s) are selected to meet the existing load with minimum demand and or energy.

10.10. Chiller Demand LimitingChiller Demand Limiting – The chiller electrical load is reduced at certain times to meet a maximum pre-specified chiller kW load.

11.11. Lighting ControlLighting Control – Turns lighting off and on di t t ti h d laccording to a pre-set time schedule.

12.12. Remote Boiler Monitoring and SupervisionRemote Boiler Monitoring and Supervision –Uses sensors at the boiler to provide inputs to the EMCS for automatic central reporting of alarms, critical operating parameters, and remote shutdown of boilers.

13.13. Maintenance ManagementMaintenance Management – Provides a maintenance schedule for utility plants, mechanical and electrical equipment based on run time, calendar time, or physical parameters.

Section V - 53

END OF SECTION V

Section V - 54