Does the calculation period always have to be on a 12-month basis?

The calculation period should cover a full 12-month period and it must be as up-to-date as possible. In cases of exceptional maintenance measures and unstable production conditions, a shorter period (for inputs and respective outputs) may be considered in case it better reflects the normal production process. Irregular activities that reflect the normal production process  must be annualized and included in the GHG calculation.

The respective period for data gathering and thus for the calculation of GHG emissions must be transparently displayed in the calculation. If the period is shorter than 12 months, adequate justification must be provided to the auditing Certification Body.