Rooftop Unit Working Group (RTUG) August 20, 2012
16
Evaluation of the RTF Standard Protocol Fan and Cooling Savings from Commercial-Sector Heat Pump Units Rooftop Unit Working Group (RTUG) August 20, 2012
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Evaluation of the RTF Standard Protocol Fan and Cooling Savings from Commercial-Sector Heat Pump Units. Rooftop Unit Working Group (RTUG) August 20, 2012. BEGINNINGS. RTUG recommendation to RTF in 2010 to add heat pumps to the RTU Protocol and Annual Energy Use and Savings Calculator - PowerPoint PPT Presentation
Transcript of Rooftop Unit Working Group (RTUG) August 20, 2012
Evaluation of the RTF Standard Protocol Fan and Cooling Savings from Commercial-Sector
Heat Pump Units
Rooftop Unit Working Group (RTUG)August 20, 2012
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ic 3BEGINNINGS
• RTUG recommendation to RTF in 2010 to add heat pumps to
the RTU Protocol and Annual Energy Use and Savings
Calculator
• 3 heat pumps were selected (Vancouver, WA) for metering for
winter-summer 2011, continuing to winter 2011-2012, and
currently into summer 2012
• Change of data service provider from Powermand to Makad
Energy disrupted data acquisition
– 1 site survived with all required data
– 1 site had most of the data
– 1 site dropped out due to gateway failure during provider
transition
RESEARCH BACKGROUNDHeat pump heating is different because it includes resistance backup heat + defrost cycles. Principal research questions included:
1. Do these heating differences fit in an energy signature model?
2. How widespread is poorly controlled/contradictory heating and cooling?
3. If the heating signature is accurately derived, how should heat pump monitoring be staged for summer/winter measurement?
METERED DATA
Per RTF/RTU protocol: One-minute data intervals
• Total power
• Outside air temperature
• Supply air temperature
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ic 3RESEARCH TASKS
• Assure measurement & data acquisition equipment installed & operating effectively properly
• Collect initial 12 months data + tracking of maintenance work done by the HVAC service techs
• Test the data with the standard RTF/RTU protocol including: – Identifying the applicable monitoring period– Making recommendations as necessary for changes in
the standard protocol to accommodate heat pumps in cooling and heating modes
– Present results to the RTUG for review and recommendations to the RTF on next steps
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ic 3HEAT PUMP SIGNATURE
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ic 3OVERALL SIGNATURE: WINTER/SUMMER
Unit 1
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ic 3METERED/PREDICTED ENERGY USE
Energy Use - Unit 1
Normalized predicted annual 41,244 kWh/yr
Actual metered (5 months) 10,537 kWh/yr
Signature predicted (5 months) 10,389 kWh/yr
Reconstruction Error 1.4%
Long-term metered energy use was constructed from the winter and summer energy signatures
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ic 3RTU PROTOCOL
HOURLY ENERGY USE PROFILES-WINTER
Unit 1
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RTU PROTOCOL HOURLY ENERGY USE PROFILES-SUMMER
Unit 1
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ic 3HEAT PUMP ANALYSIS REQUIRES
ANNUAL PERSPECTIVE• Summer signature from July or August
• Winter Signature from December or January
• September, October, November have minimal useful signature data
• Measure installation needs to be coordinated with metering
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ic 3OPERATIONAL ISSUES
Site 1 Site 2Size, tons 15 6Loading, average duty cycle
40% 40%
Observed kWh/yr 41,244 NA - missing resistance load
Est improved kWh/yr 32,540 NAEst savings, kWh/yr 8,704 NAEst savings, kWh/yr/ton 580 NARecommended EEMs • Control
adjustment - faulty interstage differential leads to unnecessary resistance heating
• 24 hour fan on lightly loaded space could be set back at night
• first stage heating has low efficiency
• Control adjustment – unnecessary use of resistance heat, reduce lockout temperature
• Possible over active de-frost with alternating cycles of heating and cooling;
• Anomalous 3 day period around 12/18 with half power and almost no heat
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ic 3RECOMMENDED NEXT STEPS
1. Update Regional RTU Research Database to included metered data from the heat pump project.
2. Notify the Vancouver facility operator of observed deficiencies in RTU operation.
3. Continuing metering/data collection for another 12 months, assuming there is continued access to the Dreamwatts system data, which is unknown at this time.
4. Adapt the RTF/RTU Standard Protocol and Calculator to produce winter signatures. In the near term, this adaptation could take the form of an adapted spreadsheet tool. The adaptation includes annualizing a normalized year estimate by dividing the year into portions associated with the winter and summer signatures.
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ic 3RECOMMENDED NEXT STEPS-2
5. Further test and substantiate the two-season signature approach
on additional heat pump units = 10 units, 5 east side, 5 west side,
with at least 6 months data, to provide for normalized annual
energy use and savings estimates in the Calculator.
6. Expand the tested application of the heat pump signature by
revisiting earlier heat pump metering data from the BPA RTU
research program and coordinate with future BPA-sponsored heat
pump metering and Pacific Northwest National Laboratory heat
pump metering that is just underway.
7. Consider proposing a heat pump addition to the RTU standard
protocol by the RTF in 2014 or sooner if additional data is
available. In this project as well as others, the existence of an
approved protocol has been shown to be a substantial analytical
time saver.
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EXPANDING THE RTF/RTU PROTOCOL NBI is developing a detailed physical RTU model for
cooling/ventilation through the Variable Rate RTU Test (VRTUT) project with NEEA/BPA
The physical model can provide measure savings estimates, benchmarking and zone characterization (net energy transfer out of the zone/space, effect of outside air temperature)
The RTF/RTU Protocol measurement approach and the aggregate results from the Calculator are not changed.
Linking the characteristics of the RTU signature to the physical circumstances of the RTU including schedules/controls, results in an enhanced predictive modeling capability supported by the energy signature under a range of variable zone and RTU operating conditions
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ic 3Contact
Mark Cherniack
Howdy Reichmuth
