For the calculation of the GHG emission factors presented in the
sections above, numerous assumptions had to be made. Each of
these assumptions might have introduced a margin of error. From
the emission factors calculated for recycling, the one factor derived
from the least number of assumptions and the most measured
parameters is the emission factor for glass. The ones with the most
assumptions used are the GHG emission factors for the different
plastic types. In particular, the use of European data on plastic production
when calculating GHG from substitution of raw plastics is
an underestimation of the likely South African emissions, which
means in reality GHG savings are higher. This is because the South
African electricity mix is different from the European one and has a
higher GHG burden. Electricity is used in the production of all
types of plastics.