May 2003

Establishing the Leakage Rates of Mobile Air Conditioners

Report on the EU Commission (DG Environment - Mr Matti Vainio)
B4-3040/2002/337136/MAR/C1
Authors: Dr. Winfried Schwarz (Öko-Recherche), Dr. Jochen Harnisch (Ecofys)

From November 2002, to January 2003 300 measurements of HFC-134a leakage were carried out on air conditioners of cars up to seven years age. The measurements were carried out on vehicles of all EU relevant makes in Germany, Portugal and Sweden reflecting different climatic conditions. The study focused entirely on "regular leakage", which takes place gradually from undamaged, functioning air conditioners.

The main results of the study are:

1. Based on the measurements, the EU wide average (un-weighted) leakage rate is estimated to be 52.4 grams per year. This equals 6.9% per year. If the leakage rates are weighted to reflect the vehicles' make composition in the EU, the leakage rate was estimated at 53.0 grams per year.

2. There is a wide distribution of leakage among different vehicles makes ranging from 28.8 grams (or 5.3%) to 81.9 grams (10.6 %) per year. This issue warrants further investigation.

3. Climatic conditions seem not to influence much the leakage rate. The differences between the leakage rates found in Sweden, Portugal, and Germany are not statistically significant.

4. Smaller charged MACs (mean fill 684 g) were found to have a smaller leakage both in absolute (44.2 grams per year) and relative (6.5% per year) terms. Larger sized MACs (mean fill 883 g) had an annual leakage rate of 66.9 grams or 7.7% per year.

The main finding of the study is that the annual weighted average “regular” leakage rate for a “second generation” mobile air conditioners is 53.0 grams per annum. This needs to be compared with the other HFC-134a emissions that occur during the lifetime of the air conditioner, especially “irregular” emissions due to accidents, stone hits, component failures. In another study (Öko-Recherche 2001) it was estimated that the “irregular” losses were about 16 grams per annum. Adding the regular and irregular emissions and assuming that the expected lifetime of a vehicle is 14 years, the expected greenhouse gas emission from a mobile air conditioner of an average in the EU is about 1,3 tonnes of CO2 equivalent.


Keywords: MAC; Mobile Air Conditioning; Lekage Rate; European Commission; HFC refrigerant emissions; R 134a.