Introduction to Building Automation Systems (BAS) - ASHRAE ...

3/11/2013

Introduction to Building Automation Systems (BAS)

Ryan R. Hoger, LEED AP 708.670.6383 [email protected]

Building Automation Systems z z z z z z z

Centralized controls Change scheduling for multiple HVAC units at same time Monitor “health” of equipment Internet accessible Alarming via text msg or email Collect/trend data Integrate to lighting control or security system

1

3/11/2013

z

DDC - Direct Digital Control of an HVAC system

z

A method of monitoring and controlling HVAC system performance by collecting, processing, and sending information using sensors, actuators, and microprocessors.

What is DDC?

z

DDC is the concept or theory of HVAC system control that uses digital controls

z

Physically, DDC encompasses all the devices used to implement this control method: a whole group of DDC controllers/microprocessors, actuators, sensors, and other devices.

What is DDC?

2

3/11/2013

DDC - the Control Theory input-process-output cycle

z

A point is ANY input or output device used to control the overall or specific performance of equipment or output devices related to the equipment.

What Is a Point?

3

3/11/2013

AI z Analog input - a sensor that monitors physical data, such as temperature, flow, or pressure. DI z Discrete input - a sensor that monitors status. Momentary and maintained switches, ON-OFF equipment status, and digital pulses from flow and electric power meters are discrete inputs. AOz Analog output - a physical action of a proportional device in the controlled equipment - e.g., actuator opens air damper from 20% to 40%, other dampers, valves, inlet guide vanes, etc. DOz Discrete output - changes or maintains device status. Performs momentary or maintained switching for start/stop of pumps, fans, two-position dampers, and on/off control. Four Kinds of Points

Input sensors and status devices react to changes in conditions. Conditions include internal load, outside air temperature, and output actions.

Output devices act based on sensor and status device reactions.

Ex. 1:

Open cooling coil valve (output action). Supply air temperature sensor

Ex. 2:

Filters on an air handler get dirty (conditions). Air switch reacts by

SAT detects (input reaction) decrease in temperature.

closing contact for “filter dirty” alarm. DDC: Actions and Reactions

4

3/11/2013

Control Point Identification Exercise

AI z

Temperature – – –

z z z z z z

DI z

Thermistors Resistance Temp. Detectors (RTDs) Transmitters

Pressure Humidity Flow (CFM, GPM) Voltage Current CO2

Switch dry contact (open or closed) – – –

z

High/low limit switch (alarm or normal) – –

z

Airflow Water Differential pressure

Freeze alarm Smoke detectors

Wattmeter pulses (pulse initiator or counter) Sensor and Status Devices used as Input Points (Reactions)

5

3/11/2013

AO

z z z

Damper actuators Modulating valves VFD

DO

z z z

Solenoid valves Relays / contactors Alarm signal

Devices used as Output Points (Actions)

Closed Loop Control is accomplished by the control signal being sent to the controlled device with constant feedback from the sensor/status device providing input to the controller. DDC: Closed Loop Control

6

3/11/2013

Closed loop control is determined by: z

Control algorithms

z

Configuration values

z

Time schedule data

z

Setpoint schedule data

Closed Loop Control

• • • • • • • •

Heating/cooling coil control Humidification/dehumidification Mixed air damper optimization VAV fan control VAV supply & return fan tracking Indoor air quality Generic PID control Control point reset

Typical Control Algorithms

7

3/11/2013

• • • • • • • • •

Time of day scheduling Discrete device controlled as analog Discrete interlock Discrete staging Proportional thermostat Primary/secondary pump control Night free cooling Adaptable start/stop Permissive interlock

Typical Control Algorithms (cont’d)

P

Proportional

PI

Proportional-Integral

PID Proportional-Integral-Derivative

Algorithm Type Used by Processor Determines Control Strategy

8

3/11/2013

PID = Proportional-Integral-Derivative Control z

z

What it is: This type of control algorithm is based on value/amount (proportion), rate of change (integral), and error allowances (derivative). PID control calculates and sends commands for outputs based on all three types of information. Advantages: More precise than P and PI controls, PID wastes less energy based on more frequent feedback and quicker responses.

What Is PID Control?

z

What it is: Control algorithm based only on value/amount (proportion).

z

Disadvantages: Less precise than PID and PI control; cannot respond to error margins or time. Uses the most energy due to over- and under- outputs. Proportional Control (P)

9

3/11/2013

z

z

What it is: Control algorithm based on value/amount (proportion), rate of change (integral). PID uses error allowances (derivative) as well. Advantages: More precise control and less energy used than proportional (P); minimum swings from setpoints. Proportional-Integral Control (PI) & (PID)

Exercise 1: Building Direct Digital Control on a CV Air Handler

10

3/11/2013

Exercise 1: Base CV Air Handler Unit -No Controls

Exercise 1: AHU - DDC Control of Start / Stop Scheduling

11

3/11/2013

Exercise 1: AHU - Add DDC Damper

Exercise 1: AHU - Add DDC Cooling Coil

Control

12

3/11/2013

Exercise 1: AHU - Add DDC Outside Air reset and Enthalpy Control

13

3/11/2013

Control Point Summary for Base CV AHU

Exercise 2: Building Direct Digital Control on a VAV Air Handler

14

3/11/2013

History z

VAV systems came into favor for mid and large size facilities in the 1960s and 1970s – – – –

z

Save energy Improve comfort Take advantage of building diversity Cooling needed year round for true interior core zones

Sequence – – –

Main AHU provides morning warm-up heat until RAT setpoint is satisfied – all zones at 100% design airflow AHU switches to 55°F discharge air controlled cooling – zones modulate CFM to controls space temp No AHU heat remainder of day – individual zone reheat or baseboard as needed

Zoning Systems

15

3/11/2013

Single Zone Systems Heating/Cooling Unit

Heating/Cooling Unit

Heating/Cooling Unit

Heating/Cooling Unit

ROOF

TMT

TMZC

TM ZONE 1

ZONE 2

ZONE 3

TM ZONE 4

Multiple Zone Systems

16

3/11/2013

To Build DDC on a VAV AHU, Start with DDC on a CV AHU...

Exercise 2: Create a VAV AHU with Inlet Guide

* If using VFD, use two Variable Frequency Drives instead, but you will still need the same control points and HPS shown.

17

3/11/2013

• Filter Status (FLTS) • FreezeStat (FRZ) • Smoke Detector (SMK)

Typical DDC Items You Can Add as Optional Items:

Exercise 2: VAV AHU with DDC Filter Status

18

3/11/2013

Exercise 2: VAV AHU with DDC FreezeStat

Exercise 2: VAV AHU with DDC Smoke Detector

19

3/11/2013

Control Point Summary for Base VAV AHU

DDC Controllers Application Specific controllers

Programmable controllers

Factory integrated controllers

20

3/11/2013

Types of Direct Digital Control Networks

z

Interface - devices and software that work as a translator between a DDC system and the humans who operate it.

z

An interface is the operator’s window into a building’s operating systems and conditions.

Interfaces to DDC

21

3/11/2013

User interfaces: •

Allow more efficient system operation monitoring. You can look at what’s happening on all floors from the tenth floor if DDC network is peer-to-peer.

•

Allow immediate diagnosis of HVAC units and controls, including changes, without physically being in front of the unit.

•

Can provide reports (e.g., historical, consumable, run times, system activity) to be used as records of building operations.

•

Can provide graphical representations of the controlled system. User Interface Benefits

User Interface Types

22

3/11/2013

Interface Examples

Hand-held Connected to a DDC Controller

PC Connected to a DDC Network Interface Examples

23

3/11/2013

Web Server Connected to DDC Network

Interface Examples

Web Interfaces z

z z z z

Standard web browser or WAP access View system status Access schedules and setpoints Trending, alarming, reporting Real time interactive graphics

24

3/11/2013

FLOOR PLAN GRAPHICS

EQUIPMENT GRAPHICS

25

3/11/2013

EQUIPMENT GRAPHICS

FLEXIBLE SCHEDULING

26

3/11/2013

TRENDING

Internet Thermostats z z z z z

Low cost alternative to BAS Direct to Ethernet No PC software – uses standard web browser No access fees Text/email alerts

27

3/11/2013

Internet Thermostats

Internet Thermostats

28

3/11/2013

Phone Apps for Thermostats

Integration z

Information Transfer –

z z

Add new HVAC equipment to an existing Building Management System

Common User Interface Building Integration – –

Lighting, HVAC, Security, Fire & Life Safety Enterprise Integration-Utilities, Financial

29

3/11/2013

Building Management Systems

Security Lighting Power Metering

HVAC

Common Protocols

PT

MODBUS®

PT

PT

30

3/11/2013

Integration Interoperability is the ability of different devices from the same or different manufacturers to function accurately together. Standard protocol - a set of guidelines for commands, inputs, and output encoding to create a universal language for all DDC devices. When the same standard protocol is used in DDC devices, interoperability is possible. Gateways - devices added to DDC networks to make standard protocols available and interoperability possible. Interoperability

BACnet

Standard protocol requirements for Building Automation and Control networking, created by ASHRAE to ensure interoperability. BACnet uses software and a LAN interface to DDC to provide: • • •

Representation of all manufacturer devices’ internal functioning in a common, network-visible way. A common command set for device services. Common encoding of commands, understandable by all devices and interfaces adhering to the protocol.

31

3/11/2013

Enterprise

CFO

Lighting

Energy

Security Systems

MODBUS

XML SQL HTTP HTML

Fire Systems

LEGACY

Open System Framework

Facility Management

ODBC SNMP JDBC

FTP

SMTP WAP

Maintenance Maintenance

HVAC Systems And More

Typical Questions z

z

Q: What part of the control system is done by the HVAC designer? What is done by the installing contractor? Do most HVAC engineers actually do control system work or is that done by specialty contractors? A: Depends on the project –

A good designer lays out the control system as an integral part of the mechanical system, including: z z

–

–

Sequence of operation Front-end/user interface details

The details of hardware, software, and cabling should be left to the contractor since every manufacturer’s system is different Unfortunately, most designers rely on manufacturers to write project specs, or worse, contractors to design in the field as they install

32

3/11/2013

Typical Questions z

z

Q: How does one select the type, number, and position of sensors? (i.e. measure temp in a room or in the supply duct? Where in the room or duct do the sensors go? How many go in each room?) A: Depends on the project –

Best to measure what you want to control – usually space temp z z

–

Mount between 4 and 5 ft high, out of direct sunlight, and in the return air path One sensor per controllable piece of equipment is best – usually one per room

Many exceptions for specialty systems and/or install cost compromises

Typical Questions z

z

Q: How does one go about determining the coefficients of a P, PI, or PID controller and tune the system once it has been installed? A: Practice and Patience –

– – –

Zero out the derivative term – HVAC equipment and building systems react too slowly for it to matter Tune the proportional term first, then worry about integral term Make small changes and monitor Use a dynamic graph

33

3/11/2013

Typical Questions z z

Q: Where can one go to get more information and training? A: –

Iowa Energy Center / Iowa State University z

–

ASHRAE Learning Institute z

– – –

www.ddc-online.org http://www.ashrae.org/education/page/1809

Continental Automated Buildings Association - www.caba.org www.automatedbuildings.com BACnet - www.bacnet.org

Case Study – Conrad Hotel 352 HVAC units

z –

311 guestrooms

Added DDC controls Occupancy sensors

z z –

Entrance door & motion

34

3/11/2013

Energy Savings Estimation Tools

Utility Rebates for Controls •

Programmable Thermostat • • •

•

Economizer Controls • •

•

Nicor Gas or NIPSCO Gas – $50 Peoples Gas or North Shore Gas – $80 Wisconsin Focus on Energy – $100 per RTU ComEd – $40 per ton Wisconsin Focus on Energy – $250 per RTU

CO2-based DCV • • • • • •

ComEd – $0.03 per ft2 DCEO – $0.28 to 0.40 per ft2 Peoples Gas or North Shore Gas – double custom NIPSCO Gas – $0.15 per ft2 Wisconsin Focus on Energy – $0.05/CFM supply Wisconsin Focus on Energy – $350 per RTU

35

3/11/2013

Utility Rebates for Controls •

Boiler Reset Control • • • •

•

Nicor Gas – $0.50 per MBH Peoples Gas or North Shore Gas – $500 NIPSCO Gas – $0.35 per MBH Wisconsin Focus on Energy – $75/controller

DDC Controls • •

•

ComEd – $0.20 per ft2 DCEO – $0.20 to 0.40 per ft2

Variable Frequency Drives (VFDs) • • • •

ComEd – $60 per Hp DCEO – $92 per Hp NIPSCO Electric - $40 per Hp Wisconsin Focus on Energy – $50 per Hp

Utility Rebates for Controls •

Hotel Guest Room Energy Mgmt System •

•

Kitchen Exhaust Demand Control Ventilation •

•

ComEd – $25 to 65 per unit ComEd – $350 per Hp

Custom Incentives (based on annual savings) • • • • •

ComEd – $0.06 to 0.07 per kWh Nicor Gas – $0.75 to 1.00 per therm Peoples Gas or North Shore Gas – $1.00 per therm DCEO – $0.12/kWh and $3.00/therm NIPSCO – $0.09/kWh and $0.60/therm

36

3/11/2013

Thanks for Coming! and Special Thanks to those who allowed me to use their graphics…

Ryan R. Hoger, LEED AP 708.670.6383 [email protected]

37