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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