direct vs. indirect emissions estimated co 2 equivalent emissions from an average supermarket...
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Direct vs. Indirect EmissionsDirect vs. Indirect Emissions
• Estimated CO2 equivalent emissions from an average supermarket– Direct = refrigerant
emissions– Indirect = energy
consumption
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Direct EmissionsDirect Emissions
• Direct GHG impacts will be assessed offline based on estimated annual refrigerant losses & GWP-weighting
– Charge Size x Emissions Rate = Total Ref Loss
• Results will be integrated to provide a “common denominator” (in MTCO2E) to compare different systems equitably
• Direct emission results will be layered over results from DOE 2.2R and EnergyPlus (i.e., indirect)
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Preliminary Assumptions for Estimating Direct EmissionsPreliminary Assumptions for Estimating Direct Emissions
System ConfigurationCentralized
Direct Expansion
DistributedSecondary
Loop
Refrigerant Type R-404A, R-507 R-404A, R-507R-404A &
glycol/ CO2
Charge Size (lbs)*
Small Supermarket (210,420 BTU) 610 490 135
Large Supermarket (713,750 BTU) 2,075 1,660 460
Big Box Food Store (1,100,042 BTU) 3,200 2,560 710
Leak Rate (percent of charge per year)
Average 18% 15% 10%
Range (of averages) 15% - 25% 10% - 15% 5% - 15%
• Charge size assumptions based on available literature; may be revised upon review of data from Savings by Design.
• Additional stakeholder data on charge size is encouraged.
Leak Reduction MeasuresLeak Reduction Measures
• Mandatory leak reduction measures will be proposed to minimize direct GHG impacts, not to enhance energy efficiency per se– No direct correlation between leakage & efficiency in large
refrigeration systems, but minimizing leakage of high-GWP refrigerants is necessary for environmental health
• Measures will reflect basic good practices/standard industry practices
Leak Reduction MeasuresLeak Reduction Measures
Focused on design & installation Developed based on:
ANSI/ASHRAE standard 147-2002 ANSI/ASHRAE 15-2007 ANSI/IIAR 2-2008 GreenChill Best Practices 2009 International Mechanical Code (IMC) Institute of Refrigeration. January 2009. Designing out leaks:
design standards and practices Institute of Refrigeration. December 2007. Code of Practice for
Refrigerant Leak Tightness in Compliance with F-Gas Regulation Industry input
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Leak Reduction MeasuresLeak Reduction Measures
Requesting stakeholder input on: Appropriateness/feasibility of draft measures Cost effectiveness Other measures to consider?
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