Up on the Rooftop: Updating HVAC Rooftop UnitPerformance
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Up on the Rooftop: Updating HVAC Rooftop UnitPerformance

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New research on rooftop units (RTUs) is now available from the California Energy Commission’s Public Interest Energy Research (PIER) program. Unitary RTUs are responsible for cooling at least half ...

New research on rooftop units (RTUs) is now available from the California Energy Commission’s Public Interest Energy Research (PIER) program. Unitary RTUs are responsible for cooling at least half the floor space in commercial buildings in the U.S., yet their actual energy performance is below what it could or should be with today’s technologies.

This presentation covers updates in two key areas of heating and cooling performance improvement in the light commercial buildings sector: (1) advanced controls and (2) performance monitoring, including fault detection and diagnostics (FDD).

The two presenters were Mark Cherniack of New Buildings Institute and Kristin Heinemeier of Western Cooling Efficiency Center at UC Davis.

For more information: www.esource.com/PIER

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Up on the Rooftop: Updating HVAC Rooftop UnitPerformance Presentation Transcript

  • 1. Up on the Rooftop:Updating HVAC Rooftop Unit Performance Mark Cherniack Kristin Heinemeier New Buildings Institute Western Cooling Efficiency Center Sponsored by the California Energy Commission Public Interest Energy Research David Weightman, Energy Commission Specialist California Energy Commission dweightm@energy.state.ca.us Jenny Field, Marketing & Outreach Associate, E Source jenny_field@esource.com
  • 2. Rooftop (RTU) HVACEmerging 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 collaborationwith 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) (90.1-2013) 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 10–20+ 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 20. LOW COOLING CAPACITY 2. SENSOR FAILURE •Low airflow rate •Low charge 3. SENSOR STUCK •Low compressor efficiency 4. SENSOR OUT OF 21. OVERCHARGE CALIBRATION 22. CONDENSER FOULING 5. IMPROPER SENSOR 23. LIQUID-LINE RESTRICTION LOCATION 24. NON-CONDENSABLE GAS 25. MALFUNCTIONING11. OVERSIZING EXPANSION DEVICE12. IMPROPER TEST AND BALANCE13. EXCESS OUTDOOR AIR INTAKE 6. COOLING/HEATING14. OVERCIRCULATION STAGE FAILURE15. EXTREMELY UNEVEN 16. LOW AIRFLOW RATE 7. COOLING/HEATING/ • Faulty fan 18. SETPOINTS NOT MET FAN CYCLING RUNTIME RATIO • Slipping belt 19. FAULTY ECONOMIZER • Fouling 8. DAMPER HUNTING CONTROL • Improper or no TAB 9. STUCK DAMPER 17. EXCESS AIRFLOW RATE 10. DAMPER LEAKAGE
  • 10. RTU R3 - repair/retrofit/replace… Unit age/end of life  Prep for lease Repair history  Availability of state or federal tax incentives Cost to repair  Utility incentives Expense vs. capital  Building energy code requirements Refrigerant type: R-410a replacing R-22  Customer/employee comfort  Owner willingness to try Corporate energy/ something new environment/sustainability policy Prep for building sale  Energy/cost (including O&M) management/savings
  • 11. PNW emerging technology framework…
  • 12. DOE/CBEA RTU challenge spec… 120,000–240,000 Btu/h (10–20 tons) capacity: Daikin-McQuay 10-ton unit Fan shall be variable or multistage operation [ASHRAE 90.1-2010 ≥ 9.2 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: http://www.pnnl.gov/uac/ [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 http://www1.eere.energy.gov/buildings/alliances/rooftop_specification.html
  • 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 – Virtual compressor temperature power consumption – Virtual heating – Virtual fan power capacity consumption – Virtual airflow rates – Virtual EER and SHR – Virtual cooling – Virtual refrigerant capacity 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!markc@newbuildings.org 509-493-4468 x17 www.newbuildings.org
  • 32.  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 InteractionUP ON THE ROOFTOP… SLIDE 33
  • 33.  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, chillersUP ON THE ROOFTOP… SLIDE 34
  • 34.  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 occurringUP ON THE ROOFTOP… SLIDE 35
  • 35. UP ON THE ROOFTOP… SLIDE 36
  • 36.  Annirudh Roy, AHRI  Jim Braun, Purdue  Anthony Hernandez, SCE  Jon Douglas, Lennox  Ay Ahmed, Sempra  KC Spivey, PG&E  Bob Cross, Xencom  Klas Berglof, ClimaCheck  Brent Eubanks, Taylor Engineering  Kristin Heinemeier, UC Davis  Cathy Chappelle, HMG  Mark Cherniack, NBI  Chris Scruton, CEC  Mark Hydeman, Taylor Engineering  Craig Fulghum, Virtjoule  Matt Tyler, PECI  Dale Gustavson, BBI  Mike Brambley, PNNL  Dale Rossi, FDSI  Nathan Taylor, Sempra  Daniel Sullivan, Target  Sean Gouw, SCE  David Yuill, Purdue  Sherry Hu, PG&E  Dick Lord, Carrier  Vance Payne, NIST  Glenn Hourahan, ACCA  Warren Lupson, AHRI  Jerine Ahmed, SCEUP ON THE ROOFTOP… SLIDE 37 37
  • 37.  NBI, 2004UP ON THE ROOFTOP… SLIDE 38
  • 38. 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 0 20 40 60 80 100 120 Number of Air Conditioners ServicedUP ON THE ROOFTOP… SLIDE 39
  • 39. UP ON THE ROOFTOP… SLIDE 40 MOWRIS 2010
  • 40. EER Failure mode penalty Low airflow: 300 cfm/ton 5% Low side HX problem incl. low airflow (50% evaporator 5% coil blockage) Refrigerant charge: 80% of nominal charge 15% Performance degradation: 30% cond. block, 300 21% cfm/ton, -10% charge 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
  • 41.  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 airUP ON THE ROOFTOP… SLIDE 42
  • 42.  Monitor operating conditions  Compare to model of expected performance  Detect discrepancies and diagnose fault  Look at other faults and find trendsUP ON THE ROOFTOP… SLIDE 43
  • 43. Quantitative Qualitative Time Series Synergy & Refrigerant Insight Clima Check Air SMDS SENSUS MI Low-cost SMDS Low-cost NILM NILM Power VirtjouleUP ON THE ROOFTOP… SLIDE 44
  • 44. Alarm Description Probable CauseT110 Circuit A Loss of Charge Low refrigerant or faulty suction pressure transducerT111 Circuit B Loss of Charge Low refrigerant or faulty suction pressure transducerT126 Circuit A High Refrigerant Pressure An overcharged system, high outdoor ambient temperature coupled with dirty outdoor coil, plugged filter drier, or a faulty high-pressure switch.T127 Circuit B High Refrigerant Pressure An overcharged system, high outdoor ambient temperature coupled with dirty outdoor coil, plugged filter drier, or a faulty high-pressure switch.T133 Circuit A Low Refrigerant Pressure 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.T134 Circuit B Low Refrigerant Pressure 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.T140 Circuit C Loss of Charge Low refrigerant or faulty suction pressure transducerT141 Circuit C Low Refrigerant Pressure 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.T142 Circuit C High Refrigerant Pressure 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 filterT414 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 Actuator load too high. Check damper load. Load Limit Alert Economizer Damper Actuator Hunting Damper position changing too quickly. Excessively Economizer Damper Stuck or Jammed No economizer motion. Check damper blades, gears,and actuator. Economizer Damper Actuator Mechanical Check actuator and replace if necessary. Failure Economizer Damper Actuator Direction Switch Actuator direction control switch (CCW, CW) wrong.UP ON THE ROOFTOP… Wrong SLIDE 45
  • 45. 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 1.7UP ON THE ROOFTOP… SLIDE 46
  • 46.  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 savingsUP ON THE ROOFTOP… SLIDE 47
  • 47.  Type of data  Number of points required  Data collection  Processing capabilities  Communications hardware and access  $400/RTU—$15,000/bldgUP ON THE ROOFTOP… SLIDE 48
  • 48.  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 seasonUP ON THE ROOFTOP… SLIDE 49
  • 49.  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 airUP ON THE ROOFTOP… SLIDE 50
  • 50.  Acceptance tests • Manufacturer must certify the diagnostic algorithms • In-field testing to confirm the diagnostic is correctly installedUP ON THE ROOFTOP… SLIDE 51
  • 51. UP ON THE ROOFTOP… SLIDE 52
  • 52. UP ON THE ROOFTOP… SLIDE 53
  • 53.  (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
  • 54.  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 ventilationUP ON THE ROOFTOP… SLIDE 55
  • 55.  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
  • 56. Mid-Term Long-Term Q3 2011 Q4 2011 Q1 2012 Q2 2012 Q3 2012 Q4 2012 Q1 2013 Q2 2013 Q3 2013 Q4 2013 Research into Residential FDDAvailability Lack of Research into FDD on Thermostat Research into Non-microprocessor Units Research FDD for Different System Types Collaboration with CEE Energy Star "Most Efficient" Criteria 2013 T24 Standard ASHRAE Standard Method of Test for RTU FDD Lack of Standards Research Laboratory Methods of Test Inventory Reach Codes Propose Reach Code FDD Requirements Propose ASHRAE Std. 90.1 FDD Requirements Propose ASHRAE Std. 189.1 FDD Requirements 2016 T24 Standard Research into Maintenance Behavior Lack of Customer Pull 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 ProgramUP ON THE ROOFTOP… SLIDE 57
  • 57.  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 roadmapUP ON THE ROOFTOP… SLIDE 58
  • 58.  Kristin Heinemeier wcec.ucdavis.edu kheinemeier@ucdavis.eduUP ON THE ROOFTOP… SLIDE 59
  • 59. Up on the Rooftop: Updating HVAC Rooftop Unit PerformanceResources• PIER Tech Briefs and Fact Sheets www.esource.com/PIER• Subscribe to Receive the Latest PIER Reports www.esource.com/PIER/subscribe• California Energy Commission Research Database www.energy.ca.gov/publications/index.php
  • 60. DiscussionQuestions and Comments?
  • 61. For More InformationDavid Weightmandweightm@energy.state.ca.usMark Cherniackmarkc@newbuildings.orgKristin Heinemeier