Part 2 Method of calculating the total global warming potential (GWP) for a preparation

The total GWP for a preparation is a weighted average, derived from the sum of the weight fractions of the individual substances multiplied by their GWPs.

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 theoretical blend of gases consisting of 23 % HFC-32; 25 % HFC-125 and 52 % HFC-134a;

Σ (23 % × 550) + (25 % × 3 400) + (52 % × 1 300)

→ Total GWP = 1 652,5.