Analysis of Average Annual Leak Rates in Comfort Cooling Appliances (August 2015)
Prepared for: Stratospheric Protection Division. Office of Air and Radiation, U.S. EPA 
Prepared by: ICF International, 1725 Eye Street NW, Washington, DC
Background
The proposed updates to the Section 608 leak inspection and repair requirements will affect appliances used for commercial refrigeration (CR), industrial process refrigeration (IPR), and comfort cooling (CC) containing 50 or more pounds of refrigerant. For the purposes of this regulation, comfort cooling is defined as stationary refrigeration equipment that provides cooling in order to control heat and/or humidity in facilities, such as office buildings and light commercial buildings. Comfort cooling appliances include building chillers and roof-top self-contained units. They may be used for the comfort of occupants or for climate control to protect equipment within a facility, such as in computer rooms. 
The current leak repair requirements require that when an owner or operator of a regulated appliance discovers that refrigerant is leaking at a rate that would exceed the applicable annual leak rate during a 12-month period, the owner or operator must take corrective action to repair the leak. For the comfort cooling sector, the current annual leak rate threshold is 15%. 
As an input to the consideration of alternative leak threshold rates for the comfort cooling sector, this memorandum compares leak rate data reported to California's Refrigerant Management Program (RMP), estimates from EPA's Vintaging Model, and recent leak rate estimates for comfort cooling systems available in the literature.
Comfort Cooling Leak Rate Data
Analysis of Data Reported under California's RMP
The basis for this analysis is system-level data reported to California's Air Resources Board (CARB) under the RMP for the 2013 calendar year. Equipment was characterized and leak rate data was analyzed to determine the amount and frequency of leaks by equipment type. Annual leak rates were calculated as the total amount of refrigerant added to a piece of equipment minus any refrigerant removed from the equipment (i.e., due to a seasonal variance) throughout the year, divided by the charge size of the equipment. This analysis classifies comfort cooling equipment into three size categories based on refrigerant charges: small (containing between 50 and 199 pounds of refrigerant), medium (containing between 200 and 2,000 pounds of refrigerant), and large (containing greater than 2,000 pounds of refrigerant)
Table 1 below shows patterns in leak rate distribution for comfort cooling systems across all refrigerant types based on the 2013 RMP data. In comfort cooling, between 74% and 79% of reported systems have a leak rate less than 5%, regardless of equipment size. 
Table 1: Leak Rates by Equipment Type
                                Equipment Type
                                     Size
                           Total Reported Equipment
                               Average Leak Rate
              Annual Leak Rate Distribution across Equipment Type
                                       
                                       
                                       
                                       
                                   0% to 5%
                                   5% to 10%
                                  10% to 15%
                                  15% to 20%
                                  20% to 25%
                                  25% to 30%
                                  30% to 35%
                                    >35%
Unitary AC
Small
                                      825
                                      15%
                                      79%
                                      0%
                                      1%
                                      1%
                                      2%
                                      1%
                                      2%
                                      13%
Chiller
Medium
                                     1,901
                                      8%
                                      74%
                                      2%
                                      3%
                                      3%
                                      3%
                                      2%
                                      2%
                                      10%
Chiller
Large
                                      85
                                      15%
                                      79%
                                      2%
                                      5%
                                      1%
                                      0%
                                      2%
                                      1%
                                      7%
Chiller
All
                                     1,986
                                      11%
                                      74%
                                      2%
                                      3%
                                      3%
                                      3%
                                      2%
                                      2%
                                      10%
CC
All
                                     2,811
                                      12%
                                      75%
                                      2%
                                      3%
                                      2%
                                      3%
                                      2%
                                      2%
                                      11%
Note: Totals may not sum due to independent rounding. 
Comparison of California RMP Data with EPA's Vintaging Model 
In Table 2, the leak rate distributions and average leak rates based on RMP data are compared against a similar analysis of information from California's South Coast Air Quality Management District (SCAQMD) Rule 1415 and EPA's nationwide Vintaging Model to ensure that leak rates reflect equipment used throughout the United States and to remove any potential bias associated with California-specific data. Table 2 indicates similarity in the distribution of leak rates between HCFC and HFC comfort cooling systems. The vast majority of systems have leaks rates less than 10% for both HCFC and HFC systems according to all three sources. 
Table 2: Leak Rate Comparison
                               Equipment Sector
                               Refrigerant Type
                            Leak Rate Distribution
                         Annual Leak Rate Distribution
         Average Leak Rate of Equipment within Leak Rate Distribution
                                       
                                       
                                       
                                   CARB RMP
                                    SCAQMD
                                      VM
                                   CARB RMP
                                    SCAQMD
                                      VM
                                      CC
                                     HCFC
                                     0-5%
                                      79%
                                      85%
                                      82%
                                     0.05%
                                     0.03%
                                     0.9%

                                       
                                     5-10%
                                      2%
                                      2%
                                      14%
                                     6.5%
                                      NA
                                     5.9%

                                       
                                     0-10%
                                      81%
                                      87%
                                      96%
                                     0.3%
                                     0.2%
                                     1.6%

                                       
                                    10-15%
                                      2%
                                      1%
                                     1.7%
                                      13%
                                      12%
                                      12%

                                       
                                    >5%
                                      21%
                                      15%
                                      18%
                                      53%
                                      NA
                                     8.2%

                                       
                                    >10%
                                      19%
                                      13%
                                      4%
                                      56%
                                      NA
                                      16%

                                       
                                    >15%
                                      17%
                                      12%
                                     2.2%
                                      58%
                                      69%
                                      21%

                                      HFC
                                     0-5%
                                      98%
                                      NA
                                      98%
                                     0.1%
                                      NA
                                     1.2%

                                       
                                     5-10%
                                     0.1%
                                      NA
                                      2%
                                     6.5%
                                      NA
                                     6.1%

                                       
                                     0-10%
                                      98%
                                      NA
                                     99.9%
                                     0.1%
                                      NA
                                     1.3%

                                       
                                    10-15%
                                     0.4%
                                      NA
                                     0.1%
                                      12%
                                      NA
                                      11%

                                       
                                    >5%
                                      2%
                                      NA
                                     0.7%
                                      51%
                                      NA
                                      9%

                                       
                                    >10%
                                      2%
                                      NA
                                     0.1%
                                      52%
                                      NA
                                      11%

                                       
                                    >15%
                                      2%
                                      NA
                                      0%
                                      62%
                                      NA
                                      NA
Note: Totals may not sum due to independent rounding. 
Additional Sources
A review of relevant literature also indicates consistency with the average leak rates for comfort cooling systems from the California RMP data and EPA's Vintaging Model, as shown in Table 3. Sources include technical reports, assumptions and guidance from other emissions models, and analyses based on industry input and leak reporting data. For the most part, these sources indicate that average leak rates for chillers are low (i.e., less than 10%) whereas unitary AC systems have slightly higher leak rates, but are generally less than 15%.  
Table 3: Average Annual CC Leak Rates from Literature
                           Average Annual Leak Rate
                                Equipment Type
                                    Source:
                                     1.4%
Medium Centrifugal Chiller
Gallagher (2013)
                                     2.4%
Large Centrifugal Chiller

                                     6.9%
Packaged Chiller

                                     11.3%
Unitary AC

                                     2-15%
Chillers
IPCC (2006)
                                      2%
Chillers
EPA Vintaging Model (2014)
                                      5%
Unitary AC

                                      3%
Chillers
UK DECC (2011)
                                      5%
Chillers
Oko-Recherche et al. (2011)
                                    5-7.5%
Chillers
UNEP (2004)
                                    15-20%
Air Conditioning (>30 kg)
Koronacki (2012)

Conclusions
A review of relevant data sources and literature indicates that a 10% applicable leak rate for comfort cooling is reasonable considering most comfort cooling equipment has an average annual leak rate less than 10% and many appliance types may achieve average annual leak rates of less than 5%. 



References

CARB. 2014. Data reported to California Air Resources Board under the Refrigerant Management Program for the 2013 calendar year. Provided to EPA and ICF on May 16, 2014. 

Gallagher, Glenn, Tao Zhan, Ying-Kuang Hsu, et. al. 2013. "High-global Warming Potential F-gas Emissions in California: Comparison of Ambient-based versus Inventory-based Emission Estimates, and Implications of Refined Estimates." Environ. Sci. Technol., 2014, 48 (2), 1084 - 1093. DOI: 10.1021/es403447v. Publication Date (Web): December 13, 2013. Copyright (C) 2013 American Chemical Society. Available at http://pubs.acs.org/doi/abs/10.1021/es403447v 

IPCC. 2006. 2006 IPCC Guidelines for National Greenhouse Gas Inventories. Volume 3: Industrial Processes and Product Use, Chapter 7: Emissions of Fluorinated Substitutes for Ozone Depleting Substances." November 2008. Available at: http://www.ipcc-nggip.iges.or.jp/public/2006gl/pdf/3_Volume3/V3_7_Ch7_ODS_Substitutes.pdf

Koronaki, I.P., D. Cowan, G. Maidment, K. Beerman, M. Schreurs, K. Kaar, I. Chaer, G. Gontarz,
R.I. Christodoulaki, and X. Cazauran. 2012. Refrigerant emissions and leakage preventing across Europe  -  Results from the RealSkillsEurope project. Energy 45 (2012) 71-80. http://dx.doi.org/10.1016/j.energy.2012.05.040. 

Stratus Consulting (Stratus). 2009. Screening Analysis to Examine the Economic Impact of Proposed Revisions to the Refrigerant Recycling and Emissions Rule. 

UK Department of Energy & Climate Change (DECC). 2011. "Development of the GHG Refrigeration and Air Conditioning Model." Prepared by ICF International. November 2011. Available at https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/48250/3844-greenhouse-gas-inventory-improvement-project-deve.PDF. 

UNEP. 2004. Report of the UNEP Technology and Economic Assessment Panel Chiller Task Force. May 2004. Available at: http://ozone.unep.org/Assessment_Panels/TEAP/Reports/Other_Task_Force/teap_chiller_report_May2004.pdf

U.S. Environmental Protection Agency (EPA). 2014. EPA's Vintaging Model. "VM IO file_v4.4_10.13.14."

