1. Operators shall determine complete and consistent data and ensure that there are no overlaps between sub-installations and no double counting. Operators shall apply the determination methods laid down in Annex VII, exercise due diligence and use data sources representing highest achievable accuracy pursuant to section 4 of Annex VII.

2. By way of derogation from paragraph 1, the operator may use other data sources in accordance with sections 4.4 to 4.6 of Annex VII, if any of the following conditions is met:

(a) the use of most accurate data sources pursuant to section 4 of Annex VII is technically not feasible;

(b) the use of most accurate data sources pursuant to section 4 of Annex VII would incur unreasonable costs;

(c) based on a simplified uncertainty assessment identifying major sources of uncertainty and estimating their associated levels of uncertainty, the operator demonstrates to the satisfaction of the regulator that the associated level of accuracy of the data source proposed by the operator is equivalent to or better than the level of accuracy of most accurate data sources pursuant to section 4 of Annex VII.