# Regulation (EU) No 517/2014 of the European Parliament and of the Council of 16 April 2014 on fluorinated greenhouse gases and repealing Regulation (EC) No 842/2006 (Text with EEA relevance), Annex IV: METHOD OF CALCULATING THE TOTAL GWP OF A MIXTURE

Extent: E+W+S+N.I.

The GWP of a mixture is calculated as a weighted average, derived from the sum of the weight fractions of the individual substances multiplied by their GWP, unless otherwise specified, including substances that are not fluorinated greenhouse gases.
Σ Substance X % × GWP + Substance Y % × GWP + … Substance N % × GWP ,
where % is the contribution by weight with a weight tolerance of +/– 1 %.
For example: applying the formula to a blend of gases consisting of 60 % dimethyl ether, 10 % HFC-152a and 30 % isobutane:
Σ 60 % × 1 + 10 % × 124 + 30 % × 3
→ Total GWP = 13,9
The GWP of the following non-fluorinated substances are used to calculate the GWP of mixtures. For other substances not listed in this annex a default value of 0 applies.
Based on the Fourth Assessment Report adopted by the Intergovernmental Panel on Climate Change, unless otherwise indicated.
Substance not listed in the Fourth Assessment Report adopted by the Intergovernmental Panel on Climate Change, default value on the basis of the GWPs of other hydrocarbons.
Substance
GWP
Common name
Industrial designation
Chemical Formula
methane
CH4
25
nitrous oxide
N2O
298
dimethyl ether
CH3OCH3
1
methylene chloride
CH2Cl2
9
methyl chloride
CH3Cl
13
chloroform
CHCl3
31
ethane
R-170
CH3CH3
6
propane
R-290
CH3CH2CH3
3
butane
R-600
CH3CH2CH2CH3
4
isobutane
R-600a
CH(CH3)2CH3
3
pentane
R-601
CH3CH2CH2CH2CH3
5
isopentane
R-601a
(CH3)2CHCH2CH3
5
ethoxyethane (diethyl ether)
R-610
CH3CH2OCH2CH3
4
methyl formate
R-611
HCOOCH3
25
hydrogen
R-702
H2
6
ammonia
R-717
NH3
0
ethylene
R-1150
C2H4
4
propylene
R-1270
C3H6
2
cyclopentane
C5H10
5

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Source: https://www.legislation.gov.uk/eur/2014/517/annex/IV (the official version)
Page: https://openlegislation.uk/eu-regulation-2014-517/annex-IV
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.