Up on the Rooftop: Updating HVAC Rooftop UnitPerformance

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 [email protected]

Jenny Field, Marketing & Outreach Associate, E Source [email protected]

mailto:[email protected]


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

http://www.pnnl.gov/uac

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!

[email protected] 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


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


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


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

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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


NBI, 2004


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


MOWRIS 2010


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%


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


Monitor operating conditions

Compare to model of expected performance

Detect discrepancies and diagnose fault

Look at other faults and find trends


Refrigerant

Air

Power

Quantitative

Qualitative Time Series

Synergy & Insight

Low-cost NILM

NILM

SMDS

SENSUS MI

Clima Check

Virtjoule

Low-cost SMDS


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.


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


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


Type of data

Number of points required

Data collection

Processing capabilities

Communications hardware and access

$400/RTU—$15,000/bldg


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


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


Acceptance tests

• Manufacturer must certify the diagnostic algorithms

• In-field testing to confirm the diagnostic is correctly installed


(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.


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


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.


Q3

2011

Q4

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Q1

2012

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2012

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Mid

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Lack

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Avai

labi

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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


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


Kristin Heinemeier wcec.ucdavis.edu [email protected]

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

http://www.esource.com/pier

http://www.esource.com/pier/subscribe

http://www.energy.ca.gov/publications/index.php

Discussion

Questions and Comments?

For More Information

David Weightman [email protected]

Mark Cherniack [email protected]

Kristin Heinemeier




Up on the Rooftop: Updating HVAC Rooftop UnitPerformance

Technology

Transcript of Up on the Rooftop: Updating HVAC Rooftop UnitPerformance