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HVAC Control Systems 101 Rich Aquino Jeff Cox

HVAC Control Systems 101 Rich Aquino Jeff Cox. What We’ll Cover. Basics of Controls Integration Between Building Systems Trane controls and energy management system Energy Saving Control Strategies Summary. Terminology. controlled variable. airflow. sensor. controller. controlled

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HVAC Control Systems 101 Rich Aquino Jeff Cox

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  1. HVAC Control Systems 101Rich AquinoJeff Cox

  2. What We’ll Cover • Basics of Controls • Integration Between Building Systems • Trane controls and energy management system • Energy Saving Control Strategies • Summary

  3. Terminology controlled variable airflow sensor controller controlled device controlled agent

  4. Open Loop outdoor-air sensor airflow controller chilled water valve

  5. Closed Loop discharge-air temperature sensor airflow controller valve chilled water

  6. Control Reset discharge-air temperature sensor outdoor-air sensor airflow controller valve chilled water

  7. Control “Points” • Binary input point (BI) • Examples: fan status (on/off), dirty filter • Binary output point (BO) • Examples: start/stop fan or pump, open/close damper • Analog input point (AI) • Examples: temperature, pressure, airflow • Analog output point (AO) • Examples: control valve or damper position • Analog Variable, Binary Variable

  8. Types of Control Action • Two-position (on/off) • Floating • Proportional • Proportional–Integral (PI) • Proportional–Integral–Derivative (PID)

  9. Two-Position (On/Off) 100% controller output 0% A on + 5°F controlled-variable deviation differential 0°F setpoint B - 5°F off time

  10. Floating 100% controller output 0% switch differential A B open + 5°F stop controlled-variable deviation differential 0°F setpoint D stop - 5°F close C time

  11. Proportional 100% controller output 0% + 5°F A offset throttling range controlled-variable deviation 0°F setpoint - 5°F time

  12. Proportional–Integral (PI) PI 100% controller output proportional integral 0% + 5°F controlled-variable deviation 0°F setpoint - 5°F time

  13. Proportional–Integral–Derivative (PID) PID 100% PI controller output derivative 0% + 5°F controlled-variable deviation 0°F setpoint - 5°F time

  14. Comparison of Control Actions P offset PID controlled-variable deviation setpoint overshoot PI time

  15. Control of an HVAC System Building Management System-Level Control Unit-Level Control

  16. Unit-Level Control Unit-Level Control

  17. Unit-Level Control

  18. System-Level Control System-Level Control Unit-Level Control

  19. Chilled-Water VAV System VAV terminal units cooling tower VAV air handler exhaust fan pumps water-cooled chiller system-level controller boiler

  20. Rooftop VAV System VAV terminal units packaged rooftop air conditioner system-level controller

  21. Building Management Building Management System-Level Control Unit-Level Control

  22. Any PC on LAN (with Internet Explorer) Access Control Panel Video Surveillance Integrated Facility Control System Integrated Facility Server Security Server Operator Workstation (Facility Commander) • View System Alarms • Check System Status • Time Control Schedules (Tracer Summit) (Tracer ES) • Create Schedules • Modify Graphics • Configure System • Access Control • Security Alarm Manager • Data Logging • Web Server District - Local Area Network (BACnet/IP) Lighting Tracer BCU JENEsys Building Controller Unit HVAC Legacy Controllers System Operator Workstation Tracer Unit Controllers • Photo ID Creation • CCTV Monitoring • Security Alarms • Security Status • Access Control

  23. Integration and Interoperability

  24. Communications Protocols • Proprietary • Used, produced, or marketed under exclusive legal right of an individual or organization • Open • Available to public domain and is shared among vendors • Standard • Open protocol that has been formalized by a governing body

  25. Gateways PC workstation Proprietary Protocol LAN Gateways HVAC Lighting Proprietary Protocol LAN Fire Protection Security Gateways

  26. System-Level Interoperability PC workstation Open, Standard protocol LAN HVAC Lighting Proprietary Protocol LAN Fire Protection Security Gateways

  27. Unit-Level Interoperability PC workstation Proprietary Protocol LAN Gateways Lighting HVAC Open, Standard Protocol LAN Fire Protection Security

  28. Binary input • Binary output • Binary value • Loop • Command • File • Calendar • Schedule • Program • Standard object types • Analog input • Analog output • Analog value • Multi-state input • Multi-state output • Device • Event enrollment • Notification class • Trend • Group • BACnet/IP, BACnet MSTP

  29. LonTalk • Rooftop unit controller • Space-comfort controller • Temperature sensor • Thermostat • Unit-ventilator controller • Variable-speed motor drive • VAV controller • LonMark functional profiles • Boiler controller • Chilled ceiling controller • Chiller • CO2 sensor • Damper actuator • Discharge-air controller • Fan-coil controller • Heat pump • Lighting-panel controller • Occupancy sensor • Pressure sensor

  30. Trane Controls and Energy Management

  31. Value to Customer System applications, pre-engineered Easy web-enabled access Improved user interface Key Features Web-based interface Scalability Smaller incremental steps to build up a system Open standard protocol support (and integration point) BACnetTM and LonTalkTM Delivery platform for engineered system applications Air systems and central plant control Building ControlTracer SC…Linking Trane systems to the Web

  32. Value to Customer Improved operating productivity Web access Integration with other systems Key Features Easy-to-use customer interface for daily building operations Web-based, remote access Multiple building scheduling and control Historical data collection and analysis System Integration platform for non-Trane BACnetTM systems Enterprise ControlTracer ES…Managing Multiple Buildings

  33. Tracer™ Architecture Firewall Tracer ES BACnet Ethernet LAN Tracer SC Building Control BuildingControl Internet/Intranet ProgrammableController AdaptiView & UC 800 ProgrammableController Field-applied Controller Air Handlers Chillers VAV

  34. Any PC on LAN (with Internet Explorer) Access Control Panel Video Surveillance Integrated Facility Control System Integrated Facility Server Security Server Operator Workstation (Facility Commander) • View System Alarms • Check System Status • Time Control Schedules (Tracer Summit) (Tracer ES) • Create Schedules • Modify Graphics • Configure System • Access Control • Security Alarm Manager • Data Logging • Web Server District - Local Area Network (BACnet/IP) Lighting Tracer BCU JENEsys Building Controller Unit HVAC Legacy Controllers System Operator Workstation Tracer Unit Controllers • Photo ID Creation • CCTV Monitoring • Security Alarms • Security Status • Access Control

  35. Education Dashboard

  36. eView – Energy Dashboard

  37. Energy Saving Control Strategies

  38. staticpressuresensor supplyfan P VAV boxes communicating BAS Energy Saving Strategies

  39. P Fan-Pressure Optimization staticpressuresensor supplyfan VAV boxes communicating BAS

  40. Fan-Pressure Optimization Benefits • Reduce supply fan energy use • Reduced pressure…. Less noise • Pressure sensor factory installed.

  41. ASHRAE Standard 62.1-2004Dynamic Reset of OA • May reset OA intake flow (or zone OA flow) in response to: • Variations in zone population (DCV) • Variations in ventilation efficiency due to changes in airflow (ventilation reset)

  42. AHU OCC OCC TOD CO2 CO2 TOD ventilation optimizationZone Level: DCV BAS lounge restroom mechroom storage office vestibule corridor elevators reception area office conference rm computer room

  43. rooftop unitwith controls • Reset outdoor airflow (Traq™ damper) OCC CO2 TOD TOD communicating BAS DDC/VAV terminals • New OA setpoint…per ASHRAE 62 • Required ventilation (TOD, OCC, CO2) • Actual primary airflow (flow sensor) ventilation optimizationSystem Level: Ventilation Reset OA SA RA CO2 OCC

  44. ventilation optimizationDCV and Ventilation Reset • Assures each zone is properly ventilated … without requiring a CO2 sensor in every zone • System-level ventilation reset equations are defined by ASHRAE 62

  45. ventilation optimizationDCV and Ventilation Reset • Assures each zone is properly ventilated … without requiring a CO2 sensor in every zone • System-level ventilation reset equations are defined by ASHRAE 62

  46. Optimization: Chiller - Tower Control • Traditional Tower Control Methods • Minimum tower LWT • Fixed design tower temperature • OAT wet bulb plus tower approach • Satisfy chiller pressure differential Reduce Operating Costs

  47. Tower Optimization - Considerations • Fan energy varies by the cube of speed changes • Example: energy change = 0.5*0.5*0.5 ~12.5% • Chiller efficiency is dependent on tower temp, chiller load and chiller type Reduce Operating Costs

  48. Trane’s Tower/Chiller Optimization Solution • Models interaction of tower and chiller • Factors ambient condition and chiller load • Factors chiller and tower - type and efficiency • Algorithm calculates optimal tower LWT • Real time control

  49. Chiller - Tower Control what is optimal? • 85 F setpoint minimizes tower energy use • 55 F setpoint minimizes chiller energy use • Wb + 6 F optimizes nothing • Recommend real time optimization Reduce Operating Costs

  50. Benefits • Reduced energy consumption • Reduced water consumption • Reduced chemical consumption • Reduced maintenance/person-hours resulting from automated control • Chiller plant will operate in a steady-state condition • Extended life cycle of equipment components • Short-term return on investment • Reduced maintenance costs

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