Up on the Rooftop: Updating HVAC Rooftop Unit Performance

Transcription

1 Up on the Rooftop: Updating HVAC Rooftop Unit Performance Mark Cherniack New Buildings Institute Kristin Heinemeier Western Cooling Efficiency Center Sponsored by the California Energy Commission Public Interest Energy Research David Weightman, Energy Commission Specialist California Energy Commission Jenny Field, Marketing & Outreach Associate, E Source jenny_field@esource.com

2 Rooftop (RTU) HVAC Emerging Technologies: Controls Performance Monitoring Fault Detection E Source-PIER December 13, 2011

3 CEC Public Interest Energy Research (PIER) FDD Project Outcomes: Team: NBI, WCEC, Purdue and collaboration with PECI on code assessment Market Characterization and FDD Characterization Report Energy, Demand and Savings Assessment Diagnostic Protocol Evaluation California Title 24 Proposal National Guidelines/Standards

4 RTU needs for deeper savings Workforce (& Customer) Education & Training Quality Installation/Quality Maintenance Requirements QI/QM Advanced Controls with Performance Monitoring/Fault Detection & Diagnostics Sensor Quality Above NEMA Premium Motors Integrated Design Practice in all EE Programs

5 Accelerating whole-building energy savings NBI - Core Performance (CP) ( ) Source: PNNL 90.1 Documentation + NBI Assessment

6 Convergence Policies : Disclosure CA 50% existing ZNE-2030 IECC IgCC submetering LEED and utility/pbc EE program requirements for performance monitoring Equipment-level emerging control/management/monitoring/reporting functionality T-Stats: web-enabled, smart, data acquisition/review Enhanced energy information/management systems/performance monitoring Control retrofits: demand controlled ventilation (DCV), variable-speed control everything FDD embedded/retrofit: alarms, trending

7 IECC 2012 adopted (IGCC at final) building metering with display + design for metering Submetering for buildings 25,000sf in total building floor area and larger Meters connected to data acquisition system with no less than 36 months of data storage with data transfer real time to a display that is permanent, readily accessible and visible display adjacent to the main building entrance or on a publicly available Internet website - Current energy demand for the whole building - Average and peak demand for the previous day and the same day the previous year - The total energy usage for the previous 18 months For buildings that are less than 25,000sf, design the energy distribution system to accommodate the future installation of submeters

8 Rooftop unit (RTU) demographics Tail end of vapor-compression thermodynamic efficiency ~ 60% of commercial buildings with RTUs ~ 60+% are 6 tons; ~80% 10 tons 65+% are electromechanically controlled, no microprocessor Natural gas 80% 90% efficient PNW: 51% in service for years; 45% are 20+ years ~70% of units have minimum possible maintenance Current economic conditions putting maintenance contracts under pressure to meet customer cost cutting

9 RTU O&M issues 1. CONTROLLER OFFLINE 2. SENSOR FAILURE 3. SENSOR STUCK 4. SENSOR OUT OF CALIBRATION 20. LOW COOLING CAPACITY Low airflow rate Low charge Low compressor efficiency 21. OVERCHARGE 22. CONDENSER FOULING 5. IMPROPER SENSOR LOCATION 23. LIQUID-LINE RESTRICTION 24. NON-CONDENSABLE GAS 11. OVERSIZING 25. MALFUNCTIONING EXPANSION DEVICE 12. IMPROPER TEST AND BALANCE 13. EXCESS OUTDOOR AIR INTAKE 14. OVERCIRCULATION 15. EXTREMELY UNEVEN RUNTIME RATIO 16. LOW AIRFLOW RATE Faulty fan Slipping belt Fouling Improper or no TAB 18. SETPOINTS NOT MET 19. FAULTY ECONOMIZER CONTROL 6. COOLING/HEATING STAGE FAILURE 7. COOLING/HEATING/ FAN CYCLING 8. DAMPER HUNTING 9. STUCK DAMPER 17. EXCESS AIRFLOW RATE 10. DAMPER LEAKAGE

10 RTU R3 - repair/retrofit/replace Unit age/end of life Repair history Cost to repair Expense vs. capital Refrigerant type: R-410a replacing R-22 Corporate energy/ environment/sustainability policy Prep for lease Availability of state or federal tax incentives Utility incentives Building energy code requirements Customer/employee comfort Owner willingness to try something new Prep for building sale Energy/cost (including O&M) management/savings

11 PNW emerging technology framework

12 DOE/CBEA RTU challenge spec 120, ,000 Btu/h (10 20 tons) capacity: Daikin-McQuay 10-ton unit Fan shall be variable or multistage operation [ASHRAE tons] DDC controller shall support full bidirectional communication read for all sensor data, all signal and status information including fault diagnostic codes and messages Online RTU comparison calculator v4.1: [very useful tool for optimizing standard unitary RTU choices] RTU shall output remotely performance metrics at least once every 15 minutes: Overall efficiency of the unit (e.g., as COP or EER) averaged over time interval between measurements Electricity use in kwh over the time interval between measurements Measured cooling (in Btu) delivered to the supply air over the time interval between measurements

13 Eugene (OR) Water & Electric Board Premium Ventilation Program Optimum start and ventilation lockout during morning warm-up enabled. Ventilation lockout reduces energy use during building startup with less heating (sometimes less cooling) of ventilation air. A properly functioning CO2 sensor satisfies this requirement. Resistance heat lockout for heat pumps. Setting resistance heat outside air lockout thermostat based on outside temperature lockout of electric resistance heat set at 30 F or lower. Reduces electric energy used for heat pump units by restricted use of resistance backup heating to colder ambient temperatures. CO2 control/dcv. Monitors inside air qualities of CO2 and varies outside air quantities to match actual occupancy requirements. CO2 sensors should be located in the return air ductwork. VSD fan control installed. Fan controls are designed to modulate fan speed to maintain discharge. Installing CO2 sensors is required to maintain ventilation when the fan speed is reduced. Minimum fan speed setting. The VSD fan controls are set to operate at 30% speed/flow when there is no call for economizing, cooling, or heating.

14 PNNL controls retrofit options PNNL Oct 2011

15 PNNL multi-measure energy savings.

16 Smart (in some cases brilliant ) T-stats shortlist

17 NBI Dreamwatts system

18 NBI Dreamwatts T-stat history

19 NBI Dreamwatts RTU1

20 Emme

21 Emme capabilities

22 Emme sensors screen

23 Emme energy use display setup

24 Advanced RTU controls shortlist

25 Cost and savings ranges...

26 Catalyst/Transformative Wave

27 Kite&Lightning/Unity

28 CEC PIER virtual sensors Using 4 existing RTU sensors + equipment technical data + manufacturers embedded alarms + weather station data Dr. Haorong Li/Univ. Nebraska Virtual OA fraction Virtual building load Virtual mixed air temperature Virtual heating capacity Virtual airflow rates Virtual cooling capacity Virtual compressor power consumption Virtual fan power consumption Virtual EER and SHR Virtual refrigerant charge

29 Controls roadmap on-ramps How do facility owners/occupants/mechanical contractors take advantage of the active monitoring capabilities, embedded or added on, of any particular product? Assess cost-benefit of a range of control products: functional testing, verification, accuracy, persistence Expanded controls demonstration/measurement programs Assess need for a commercial Controls Guide or guidance covering a wide range of control/monitoring approaches and products for various markets Identify linkages related to advanced controls to Workforce Education and Training activities

30 Takeaways Workforce (& Customer) Education & Training Quality Installation/Quality Maintenance Requirements QI/QM Sensor Quality Advanced Controls with Performance Monitoring/Fault Detection & Diagnostics Above NEMA Premium Motors Integrated Design Practice in All EE Programs

31 Thanks! x17

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33 Fault Detection and Diagnostics Western Cooling Challenge: RTU Design RTU Retrofit Design Retrofit Demonstrations Water Use and Quality HVAC Maintenance Technician Instrument Test Lab HVAC/Human Interaction UP ON THE ROOFTOP SLIDE 33

34 Fault detection and diagnosis Identify if a system deviates from expected operation Diagnose or isolate faults from other potential faults Annunciate and manage fault alerts Common in various industries Automotive: powertrain Space exploration Nuclear power HVAC: VAV AHUs, chillers UP ON THE ROOFTOP SLIDE 34

35 All new residential construction in California will be zero net energy by 2020 All new commercial construction in California will be zero net energy by 2030 HVAC will be transformed to ensure that its energy performance for California s climate is optimal Compliance, Quality Installation and Maintenance, Whole Building, Advanced Technologies Strategy 4-5: Develop nationwide standards and/or guidelines for onboard diagnostic functionality and specifications for designated sensor mount locations Strategy 4-6: Prioritize in-field diagnostic and maintenance approaches based on the anticipated size of savings, cost of repairs, and the frequency of faults occurring UP ON THE ROOFTOP SLIDE 35

36 UP ON THE ROOFTOP SLIDE 36

37 Annirudh Roy, AHRI Anthony Hernandez, SCE Ay Ahmed, Sempra Bob Cross, Xencom Brent Eubanks, Taylor Engineering Cathy Chappelle, HMG Chris Scruton, CEC Craig Fulghum, Virtjoule Dale Gustavson, BBI Dale Rossi, FDSI Daniel Sullivan, Target David Yuill, Purdue Dick Lord, Carrier Glenn Hourahan, ACCA Jerine Ahmed, SCE Jim Braun, Purdue Jon Douglas, Lennox KC Spivey, PG&E Klas Berglof, ClimaCheck Kristin Heinemeier, UC Davis Mark Cherniack, NBI Mark Hydeman, Taylor Engineering Matt Tyler, PECI Mike Brambley, PNNL Nathan Taylor, Sempra Sean Gouw, SCE Sherry Hu, PG&E Vance Payne, NIST Warren Lupson, AHRI UP ON THE ROOFTOP SLIDE 37 37

38 NBI, 2004 UP ON THE ROOFTOP SLIDE 38

39 Airflow Adjustments Cleaned Fan Cleaned Condenser Coil Cleaned Evaporator Coil Economizer Adjusted or Repaired Refrigerant Charge Adjusted Thermostat Reprogrammed Thermostat Replaced Installed new valve caps Further Service Needed or AirCare Plus Incomplete AirCare Plus Completed with No Maintenance Conducted Total Number of Units Visited by AirCare Plus Number of Air Conditioners Serviced UP ON THE ROOFTOP SLIDE 39

40 UP ON THE ROOFTOP SLIDE 40 MOWRIS 2010

41 Failure mode EER penalty Low airflow: 300 cfm/ton 5% Low side HX problem incl. low airflow (50% evaporator coil blockage) 5% Refrigerant charge: 80% of nominal charge 15% Performance degradation: 30% cond. block, 300 cfm/ton, -10% charge 21% Refrigerant line non-condensables 8% High side HX problem (50% condenser coil blockage) 9% Compressor short cycling 10% Refrigerant line restrictions/txv problems 56% UP ON THE ROOFTOP SLIDE 41

42 Air temperature sensor failure/fault High/low refrigerant charge Compressor short cycling Refrigerant line restrictions/txv problems Refrigerant line non-condensables High/low side HX problem Capacity degradation Efficiency degradation Not economizing when it should Damper not modulating Excess outdoor air UP ON THE ROOFTOP SLIDE 42

43 Monitor operating conditions Compare to model of expected performance Detect discrepancies and diagnose fault Look at other faults and find trends UP ON THE ROOFTOP SLIDE 43

44 Quantitative Qualitative Time Series Refrigerant Synergy & Insight Clima Check Air SMDS SENSUS MI Power NILM Low-cost SMDS Low-cost NILM Virtjoule UP ON THE ROOFTOP SLIDE 44

45 Alarm Description T110 Circuit A Loss of Charge T111 Circuit B Loss of Charge T126 Circuit A High Refrigerant Pressure T127 Circuit B High Refrigerant Pressure T133 Circuit A Low Refrigerant Pressure T134 Circuit B Low Refrigerant Pressure T140 Circuit C Loss of Charge T141 Circuit C Low Refrigerant Pressure T142 Circuit C High Refrigerant Pressure Probable Cause Low refrigerant or faulty suction pressure transducer Low refrigerant or faulty suction pressure transducer An overcharged system, high outdoor ambient temperature coupled with dirty outdoor coil, plugged filter drier, or a faulty high-pressure switch. An overcharged system, high outdoor ambient temperature coupled with dirty outdoor coil, plugged filter drier, or a faulty high-pressure switch. Low refrigerant charge, dirty filters, evaporator fan turning backwards, loose or broken fan belt, plugged filter drier, faulty transducer, excessively cold return air, or stuck-open economizer when the ambient temperature is low. Low refrigerant charge, dirty filters, evaporator fan turning backwards, loose or broken fan belt, plugged filter drier, faulty transducer, excessively cold return air, or stuck-open economizer when the ambient temperature is low. Low refrigerant or faulty suction pressure transducer Low refrigerant charge, dirty filters, evaporator fan turning backwards, loose or broken fan belt, plugged filter drier, faulty transducer, excessively cold return air, or stuck-open economizer when the ambient temperature is low. An overcharged system, high outdoor ambient temperature coupled with dirty outdoor coil, plugged filter drier, or a faulty high-pressure switch. T408 Dirty Filter Dirty filter T414 Economizer Damper Actuator Out of Calibration Calibrate economizer (E.CAL). If problem still exists, then determine what is limiting economizer rotation. Economizer Damper Actuator Torque Above Load Limit Alert Economizer Damper Actuator Hunting Excessively Economizer Damper Stuck or Jammed Economizer Damper Actuator Mechanical Failure Economizer Damper Actuator Direction Switch Actuator load too high. Check damper load. Damper position changing too quickly. No economizer motion. Check damper blades, gears,and actuator. Check actuator and replace if necessary. Actuator direction control switch (CCW, CW) wrong. UP ON Wrong THE ROOFTOP SLIDE 45

46 Incremental Installed Cost $1,600 Incremental Annual Maintenance, 54 kbtuh ($74) PV of Annual Maintenance, 54 kbtuh ($878) Total Incremental Cost, 54 kbtuh $722 PV of Energy Savings, 54 kbtuh $1,197 Lifecycle cost savings $475 Benefit/Cost Ratio 1.7 UP ON THE ROOFTOP SLIDE 46

47 Based on EnergyPro simulations Fault impact on EER and annual energy use Range of building types and climate zones Probabilities used for: Probability that fault will occur Probability that it will be detected with FDD Probability that it would have been detected w/o FDD Time-dependent valuation of savings UP ON THE ROOFTOP SLIDE 47

48 Type of data Number of points required Data collection Processing capabilities Communications hardware and access $400/RTU $15,000/bldg UP ON THE ROOFTOP SLIDE 48

49 Improve comfort Reduce operating costs Utility costs Preserve equipment longevity e.g., early detection of small malfunctions to preserve compressor Reduce service costs Reduced PM inspections Fault prevention Schedule multiple service activities Shift service to low season UP ON THE ROOFTOP SLIDE 49

50 All unitary DX units with an economizer and mechanical cooling capacity 4.5 tons shall be equipped with embedded, automated FDD with remote communications capability The FDD system shall detect the following faults: Air temperature sensor failure/fault Not economizing when it should Economizing when it should not Damper not modulating Excess outdoor air UP ON THE ROOFTOP SLIDE 50

51 Acceptance tests Manufacturer must certify the diagnostic algorithms In-field testing to confirm the diagnostic is correctly installed UP ON THE ROOFTOP SLIDE 51

54 (Residential) Furnaces, Central AC, air source heat pumps and ground source heat pumps must have communications, diagnostic and automated configuration capability as defined below: Diagnostics: Units shall be able to transmit any fault codes which indicate a need for technician service to at least one system controller model that is available for sale. With this information, the control device is able to advise homeowners to call their service personnel. UP ON THE ROOFTOP SLIDE 54

55 RTU shall support the following diagnostic services: 1. Low Evaporator Airflow 2. High Refrigerant Charge 3. Low Refrigerant Charge 4. Sensor Failure/Fault (including drifting out of calibration) 5. Equipment Short Cycling 6. Dirty Filter 7. Efficiency Degradation 8. Capacity Degradation 9. Economizer Faults a. Damper not modulating (stuck damper) b. Not economizing when it should c. Excess outdoor air d. Low ventilation UP ON THE ROOFTOP SLIDE 55

56 Title: Laboratory Method of Test of Fault Detection and Diagnostics Applied to Commercial Air-Cooled Packaged Systems Purpose: This standard provides a method to define an FDD tool s function. This standard also provides a method of laboratory test for the performance of Fault Detection and Diagnostic (FDD) tools on commercial air-cooled packaged equipment. Scope: This standard applies to commercial air-cooled packaged air-conditioning systems. The test is a physical laboratory test on a particular combination of diagnostic tool for each model of a unitary system. This standard applies to any on-board, aftermarket, or handheld hardware and/or software functionality that detects and/or diagnoses problems that lead to degraded performance, such as energy efficiency, capacity, increased maintenance costs, or shortened equipment life. UP ON THE ROOFTOP SLIDE 56

57 Lack of Availability Q Q Q Q Q Q Q Q Q Q Mid-Term Long-Term Research into Residential FDD Research into FDD on Thermostat Research into Non-microprocessor Units Research FDD for Different System Types Lack of Standards Collaboration with CEE Energy Star "Most Efficient" Criteria 2013 T24 Standard ASHRAE Standard Method of Test for RTU FDD Research Laboratory Methods of Test Inventory Reach Codes Propose Reach Code FDD Requirements Propose ASHRAE Std FDD Requirements Propose ASHRAE Std FDD Requirements 2016 T24 Standard Lack of Customer Pull Research into Maintenance Behavior High-Performance RTU Challenge Research into Fault Incidence Cost-Effectiveness Assessment and Dissemination Program Pilot Test Case Studies Research into Market Acceptability Design IOU FDD Program Launch IOU FDD Program UP ON THE ROOFTOP SLIDE 57

58 FDD is a technology on the brink of marketization FDD can detect problems that are frequent and serious FDD can be cost-effective Building codes can include requirements for FDD Methods of testing must be developed first The Performance Alliance is developing a roadmap UP ON THE ROOFTOP SLIDE 58

59 Kristin Heinemeier wcec.ucdavis.edu UP ON THE ROOFTOP SLIDE 59

60 Up on the Rooftop: Updating HVAC Rooftop Unit Performance Resources PIER Tech Briefs and Fact Sheets Subscribe to Receive the Latest PIER Reports California Energy Commission Research Database

61 Discussion Questions and Comments?

62 For More Information David Weightman Mark Cherniack Kristin Heinemeier