Uncertainties related to emissions factors (UFE) are directly defined by the Bilan Carbone® methodology or the GHG protocol methodology.
The total uncertainty of an emission source is defined by:
UPost = √(UFE2)+(Udata2)
UFE: the uncertainty of the emission factor
UData: the uncertainty of the respective data at each position
UPost: the overall uncertainty of the position
UPost is then multiplied by the emissions (in CO2e) of the source concerned.
The product of the uncertainties of each source and the emissions of each corresponding source gives the total uncertainty (in CO2e).
Note that the confidence interval used in GHG inventories is 95%; this confidence interval is the interval centered on the value retained for a data in which it is 95% likely that the true value of this data is included.