Optimizing BAS Information for Operator Effectiveness and Optimal Control

Transcription

1 Optimizing BAS Information for Operator Effectiveness and Optimal Control Len Beyea, CBCxP, EBCxP, HBDP, CEM, LEED AP Principal RetroCom Energy Strategies, Inc.

2 AIA Quality Assurance The Building Commissioning Association is a Registered Provider with The American Institute of Architects Continuing Education Systems (AIA/CES). Credit(s) earned on completion of this program will be reported to AIA/CES for AIA members. Certificates of Completion for both AIA members and non-aia members are available upon request. This program is registered with AIA/CES for continuing professional education. As such, it does not include content that may be deemed or construed to be an approval or endorsement by the AIA of any material of construction or any method or manner of handling, using, distributing, or dealing in any material or product. Questions related to specific materials, methods, and services will be addressed at the conclusion of this presentation.

3 Course Description Building automation systems have become standard tools for facility operation and monitoring, and commissioning providers use them routinely to gather data and to test system operation. But for O&M staff who are responsible for day-to-day facility operations, the BAS often becomes nothing more than a remote monitoring and control device, with automation and optimization sacrificed for the expediency of particular circumstances. Engaging operators in developing the graphical interface and defining parameters of override functions gives them greater ownership of the BAS as an O&M tool, facilitates effective use, and protects the performance integrity of the system.

4 Learning Objectives At the end of this session, participants will be able to: 1. Evaluate existing or planned operator interfaces for building automation systems for their suitability and utility based on interviews with building operators and evaluation of system types. 2. Identify the information and control authority needed by building operators to deal with operational problem examples without undermining control objectives. 3. Use examples for augmenting or specifying BAS workstation display contents to enhance operator performance. 4. Facilitate input from building operators to develop improved BAS operator interface.

5 Outline Acknowledgements Building Automation Systems in the real world O&M Issues Understanding the operators perspective and designing BAS interface for daily use Gaining buy-in from building operators for optimization strategies Examples and Conclusions

6 Acknowledgements Mike Goodrich, Director, Energy & Utilities, Los Rios Community College District Ted Dahlkamp, Control Systems Designer, Honeywell Home and Building Control LRCCD Facilities Team

7 BAS the reality Most systems do not fulfill potential or meet expectations

8 Sources of BAS deficiencies Specifications are insufficient, generic, and/or provided by manufacturer A lot of setpoints are guess points Optimization strategies never implemented Operators not adequately trained Not thoroughly commissioned Operators not consulted in development of interface

9 Results

10 Override of program

11 Control parameters overridden Equipment operating continuously that should operate on a schedule and/or with temperature lockouts Setpoints that should adjust to changing loads become fixed Interlocks and integration of operating modes no longer function

12 Manual control remains indefinitely Operator overrides usually remain in place until the next round of complaints Automatic schedule, lockout, and reset functions abandoned

13 Operator s perspective First responsibility is to satisfy occupants Deficiencies in design or installation of BAS are beyond the operator s capacity to correct Lack of goals or metrics for energy are reflected in O&M priorities Lack of training to enable operators to understand control strategies

14 Role of the Operator Interface Monitor status of systems Manage control parameters Record operating data Diagnose problems before going to equipment location

15 Operator Workstation Displays

16 What do operators need to know? Is it working? Are conditions that may generate complaints within appropriate limits? Do operating parameters correspond to control commands? Do control commands make sense? How does one system compare to another? How does current operation compare to previous operation?

17 Example from LRCCD

18 Benefits of summary tables Information likely to require immediate attention is all on one page Goes beyond customary priorities Is it running? / Is it comfortable? To add: Is it working right? Programmed overrides are immediately evident

19 Zooming in

20 Programmed vs. Manual Overrides Programmed overrides change an operating mode based on trigger events, e.g. temperature or pressure outside a limit range, activation of afterhours override switch Manual override executed by operators with access to the BAS program manually manipulating a point value to be other than what the program does automatically

21 Links Links between screens allow operators to access related information quickly Links provide choices of what related information to access first Links should be relevant to the information displayed, not random. Links should provide expedient path to needed information, both when things are working well and when they aren t

22 LRCCD Home Screen

23 Folsom Lake College Home Screen

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25 More links

26 FLC Cypress AH5

27 What to override? Operating status (control output) Setpoint Setpoint limits (reset ramp; hi/lo limits) Lockout temperature Sensor values Safety interlock Safety limits

28 What to override? Operating status (control output) Setpoint Setpoint limits (reset ramp; hi/lo limits) Lockout temperature Sensor values (only when failed) Safety interlock Safety limits

29 How long to override? Hours Days Week Indefinite

30 How long to override? Hours Days Week Indefinite Ideally, a weekly sweep of overrides not on Monday or Friday facilitates management of problems

31 What takes precedence? If operating modes (e.g. occupied, morning warm-up, unoccupied, occupant override) are defined, certain modes can be programmed to override an operator override Staging sequence can preserve performance when one stage is in manual control Safeties should always take precedence

32 Operator notes

33 Operator notes

34 Operator buy-in to control optimization The best consultant doesn t know a building like its operators do Bringing operators into the discussion of control intent enables them to put their knowledge to work Automating intelligence requires complexity DDC offers infinite potential for control complexity

35 Economizer example Old way: Fixed temperature enable setpoint Electrical interlocks with call for cooling Mechanical stop for minimum ventilation

36 Economizer example New way: Enabled on differential temperature or enthalpy Software interlock with call for cooling Minimum ventilation setting varies with operating mode, airflow reading/fan speed, and sometimes CO 2 Separate parameters for night purge cooling

37 LRCCD example Supply Air Reset

38 12 of 22 AHUs SA Setpoint Overridden

39 Proposed change Observed that VAV boxes were often all at reduced volumes, even with reset working Proposed resetting based on maximum VAV zone demand Discussions with staff and BAS programmer led to using number of cooling and heating requests as basis for reset

40 Input incorporated into new display

41 Revisiting BAS Specification

42 Specifying Installation Standards Panel locations and mounting Accessible wire terminations Wire & panel labels Where raceway is and is not required Performance of sensors and interface devices

43 Specifying Documentation & Training As-built control drawings & manuals Operator training Warranty period technical support

44 Specifying Sequence of Operations Heart of BAS serving its purpose Intended control outcomes in every operating mode Control strategies and parameters Alarm limits and delays Software interlocks Which parameters are adjustable

45 Specifying Workstation Displays List of displays Display descriptions Links between displays Where operator override is accessed If new construction defer details until commissioning

46 Getting operator input Bring the facility operations team together Describe the types of new systems or review the existing systems that will be controlled Describe the performance objectives, and the control strategies that are planned to achieve those objectives Ask what issues operators anticipate with each automatic control strategy Ask operators what information they need to know to identify problems include this information in displays Ask what operators need to be able to change to address problems, and explore the possible scenarios this is the basis for override parameters and prioritization of authority Ask what else they would like to see in the system

47 Commissioning intent Make sure systems operate according to design intent Sometimes we can improve the design Making control systems more usable, resilient, adaptable, and maintainable has long-term benefits for building performance

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50 THANK YOU! Len Beyea, Principal x102