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%
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

>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

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