Post on 23-Jan-2015
description
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 dweightm@energy.state.ca.us
Jenny Field, Marketing & Outreach Associate, E Source jenny_field@esource.com
Rooftop (RTU) HVAC
Emerging Technologies: Controls
Performance Monitoring Fault Detection
E Source-PIER
December 13, 2011
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
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
Accelerating whole-building energy savings…
Source: PNNL 90.1 Documentation + NBI Assessment
NBI - Core Performance (CP)
(90.1-2013)
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
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
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
RTU O&M issues… 1. CONTROLLER OFFLINE
2. SENSOR FAILURE
3. SENSOR STUCK
4. SENSOR OUT OF CALIBRATION
5. IMPROPER SENSOR LOCATION
6. COOLING/HEATING STAGE FAILURE
7. COOLING/HEATING/ FAN CYCLING
8. DAMPER HUNTING
9. STUCK DAMPER
10. DAMPER LEAKAGE
11. OVERSIZING
12. IMPROPER TEST AND BALANCE
13. EXCESS OUTDOOR AIR INTAKE
14. OVERCIRCULATION
15. EXTREMELY UNEVEN RUNTIME RATIO
17. EXCESS AIRFLOW RATE
18. SETPOINTS NOT MET
19. FAULTY ECONOMIZER CONTROL
20. LOW COOLING CAPACITY •Low airflow rate •Low charge •Low compressor efficiency
16. LOW AIRFLOW RATE • Faulty fan • Slipping belt • Fouling • Improper or no TAB
21. OVERCHARGE
22. CONDENSER FOULING
23. LIQUID-LINE RESTRICTION
24. NON-CONDENSABLE GAS
25. MALFUNCTIONING EXPANSION DEVICE
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 building sale
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
Energy/cost (including O&M)
management/savings
PNW emerging technology framework…
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
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.
PNNL controls retrofit options…
PNNL Oct 2011
PNNL multi-measure energy savings….
Smart (in some cases ‘brilliant’) T-stats shortlist…
NBI Dreamwatts system…
NBI Dreamwatts T-stat history…
NBI Dreamwatts – RTU1…
Emme…
Emme capabilities…
Emme sensors screen…
Emme energy use display setup…
Advanced RTU controls shortlist…
Cost and savings ranges...
Catalyst/Transformative Wave…
Kite&Lightning/Unity…
CEC PIER virtual sensors…
– Virtual OA fraction – Virtual mixed air
temperature
– Virtual heating capacity
– Virtual airflow rates – Virtual cooling
capacity
– Virtual building load – Virtual compressor
power consumption – Virtual fan power
consumption – Virtual EER and SHR – Virtual refrigerant
charge
Using 4 existing RTU sensors + equipment technical data + manufacturers’ embedded alarms + weather station data — Dr. Haorong Li/Univ. Nebraska
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
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
Thanks!
markc@newbuildings.org 509-493-4468 x17
www.newbuildings.org
UP ON THE ROOFTOP… SLIDE 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 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 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 36
UP ON THE ROOFTOP… SLIDE 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
37
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 38
NBI, 2004
UP ON THE ROOFTOP… SLIDE 39
0 20 40 60 80 100 120
Total Number of Units Visited by AirCare Plus
AirCare Plus Completed with No Maintenance Conducted
Further Service Needed or AirCare Plus Incomplete
Installed new valve caps
Thermostat Replaced
Thermostat Reprogrammed
Refrigerant Charge Adjusted
Economizer Adjusted or Repaired
Cleaned Evaporator Coil
Cleaned Condenser Coil
Cleaned Fan
Airflow Adjustments
Number of Air Conditioners Serviced
UP ON THE ROOFTOP… SLIDE 40
MOWRIS 2010
UP ON THE ROOFTOP… SLIDE 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 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 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 44
Refrigerant
Air
Power
Quantitative
Qualitative Time Series
Synergy & Insight
Low-cost NILM
NILM
SMDS
SENSUS MI
Clima Check
Virtjoule
Low-cost SMDS
UP ON THE ROOFTOP… SLIDE 45
Alarm Description Probable Cause
T110 Circuit A Loss of Charge Low refrigerant or faulty suction pressure transducer
T111 Circuit B Loss of Charge Low refrigerant or faulty suction pressure transducer
T126 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 transducer
T141 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 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
Actuator load too high. Check damper load.
Economizer Damper Actuator Hunting Excessively
Damper position changing too quickly.
Economizer Damper Stuck or Jammed No economizer motion. Check damper blades, gears,and actuator.
Economizer Damper Actuator Mechanical Failure
Check actuator and replace if necessary.
Economizer Damper Actuator Direction Switch Wrong
Actuator direction control switch (CCW, CW) wrong.
UP ON THE ROOFTOP… SLIDE 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 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 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 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 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 51
Acceptance tests
• Manufacturer must certify the diagnostic algorithms
• In-field testing to confirm the diagnostic is correctly installed
UP ON THE ROOFTOP… SLIDE 52
UP ON THE ROOFTOP… SLIDE 53
UP ON THE ROOFTOP… SLIDE 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 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 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 57
Q3
2011
Q4
2011
Q1
2012
Q2
2012
Q3
2012
Q4
2012
Q1
2013
Q2
2013
Q3
2013
Q4
2013
Mid
-Ter
m
Long
-Ter
m
Lack
of
Avai
labi
lity Research into Residential FDD
Research into FDD on Thermostat Research into Non-microprocessor Units Research FDD for Different System Types
Collaboration with CEE
Energy Star "Most Efficient" Criteria
Lack
of S
tand
ards
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. 90.1 FDD Requirements Propose ASHRAE Std. 189.1 FDD Requirements 2016 T24 Standard
Lack
of C
usto
mer
Pul
l 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 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 59
Kristin Heinemeier wcec.ucdavis.edu kheinemeier@ucdavis.edu
Up on the Rooftop: Updating HVAC Rooftop Unit Performance
Resources • 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
Discussion
Questions and Comments?
For More Information
David Weightman dweightm@energy.state.ca.us
Mark Cherniack markc@newbuildings.org
Kristin Heinemeier