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Home , Air handler, Building automation, Damper (flow), Programmable thermostat, Proportional control

3/11/2013

Introduction to Building Systems (BAS)

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

Building Automation Systems

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

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z DDC - of an HVAC system

z A method of monitoring and controlling HVAC system performance by collecting, processing, and sending information using , , 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?

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DDC - the 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?

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AI z Analog input -a that monitors physical data, such as , flow, or pressure. DI z Discrete input -a sensor that monitors status. Momentary and maintained , 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., opens air from 20% to 40%, other dampers, , inlet guide vanes, etc. DOz Discrete output - changes or maintains device status. Performs momentary or maintained switching for start/stop of , fans, two-position dampers, and on/off control. Four Kinds of Points

Input sensors and status Output devices act based devices react to changes in on sensor and status conditions. Conditions device reactions. include internal load, outside air temperature, and output actions.

Ex. 1: Open cooling coil (output action). Supply air temperature sensor SAT detects (input reaction) decrease in temperature.

Ex. 2: Filters on an get dirty (conditions). Air reacts by closing contact for “filter dirty” alarm.

DDC: Actions and Reactions

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Control Point Identification Exercise

AI DI z Temperature z Switch dry contact – (open or closed) – Resistance Temp. Detectors – (RTDs) – – Transmitters – Differential pressure z Pressure z High/low limit switch z (alarm or normal) z Flow (CFM, GPM) – Freeze alarm – Smoke detectors z Voltage z Wattmeter pulses z Current (pulse initiator or z CO2 counter)

Sensor and Status Devices used as Input Points (Reactions)

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AO z Damper actuators DO z Solenoid valves z Modulating valves z Relays / z VFD contactors z 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

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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 control • VAV supply & return fan tracking • • Generic PID control • Control point reset

Typical Control Algorithms

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• Time of day scheduling • Discrete device controlled as analog • Discrete interlock • Discrete staging • Proportional • Primary/secondary control • Night • 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

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PID = Proportional-Integral-Derivative Control

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. z 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)

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z What it is: Control algorithm based on value/amount (proportion), rate of change (integral). PID uses error allowances (derivative) as well. z 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

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Exercise 1: Base CV Air Handler Unit -No Controls

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

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Exercise 1: AHU - Add DDC Damper

Exercise 1: AHU - Add DDC Cooling Coil

Control

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

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Control Point Summary for Base CV AHU

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

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History z VAV systems came into favor for mid and large size facilities in the 1960s and 1970s – Save energy – Improve comfort – Take advantage of building diversity – Cooling needed year round for true interior core zones z 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

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Single Zone Systems

Heating/Cooling Heating/Cooling Heating/Cooling Heating/Cooling Unit Unit Unit Unit ROOF

TMT TM TMZC TM

ZONE 1 ZONE 2 ZONE 3 ZONE 4

Multiple Zone Systems

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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.

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• 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

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Exercise 2: VAV AHU with DDC FreezeStat

Exercise 2: VAV AHU with DDC Smoke Detector

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Control Point Summary for Base VAV AHU

DDC Controllers

Application Programmable Specific controllers controllers

Factory integrated controllers

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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

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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

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Interface Examples Hand-held Connected to a DDC Controller

PC Connected to a DDC Network Interface Examples

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Web Server Connected to DDC Network Interface Examples

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

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FLOOR PLAN GRAPHICS

EQUIPMENT GRAPHICS

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EQUIPMENT GRAPHICS

FLEXIBLE SCHEDULING

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TRENDING

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

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Internet Thermostats

Internet Thermostats

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Phone Apps for Thermostats

Integration z Information Transfer – Add new HVAC equipment to an existing Building Management System z Common User Interface z Building Integration – Lighting, HVAC, Security, Fire & Life Safety – Enterprise Integration-Utilities, Financial

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Building Management Systems

Security Lighting HVAC Power Metering

Common Protocols

PT ® PT

PT

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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 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.

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Enterprise

Lighting CFO Security Systems Energy XML SQL MODBUS HTTP HTML Facility Open System ODBC SNMP Management JDBC FTP LEGACY Framework Fire Systems

SMTP

WAP MaintenanceMaintenance

HVAC Systems And More

Typical Questions

z Q: What part of the 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? z A: Depends on the project – A good designer lays out the control system as an integral part of the mechanical system, including: z Sequence of operation z 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

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Typical Questions

z Q: How does one select the type, number, and position of sensors? (i.e. measure temp in a room or in the supply ? Where in the room or duct do the sensors go? How many go in each room?) z A: Depends on the project – Best to measure what you want to control – usually space temp z Mount between 4 and 5 ft high, out of direct sunlight, and in the return air path z 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 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? z 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

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Typical Questions

z Q: Where can one go to get more information and training? z A: – Iowa Energy Center / Iowa State University z www.ddc-online.org – ASHRAE Learning Institute z 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

z 352 HVAC units – 311 guestrooms z Added DDC controls z Occupancy sensors – Entrance door & motion

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Energy Savings Estimation Tools

Utility Rebates for Controls

• • Nicor Gas or NIPSCO Gas – $50 • Peoples Gas or North Shore Gas – $80 • Wisconsin Focus on Energy – $100 per RTU • Controls • 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

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Utility Rebates for Controls

• 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 • ComEd – $25 to 65 per unit • Kitchen Exhaust Demand Control Ventilation • 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

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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]

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