Methodological choice and Key category analysis

This chapter from the EMEP Guidebook explains the tiered approach used to define the generic levels of detail and rigour required for inventory compilation and how to identify the key categories for which higher tiered methods are required. This chapter draws extensively on guidance issued by the Intergovernmental Panel on Climate Change for estimating emissions of greenhouse gases, and in particular the 2006 IPCC Guidelines for National Greenhouse Gas Inventories (2006 Guidelines) (IPCC 2006) and its 2019 Refinement (IPCC, 2019).
Methodological choice for individual source categories is important in managing overall inventory quality and minimising u certainty. Generally, inventory uncertainty is lower when emissions are estimated using the most rigorous, higher tiered, methods (see subsection 1.1.3) provided for each category or subcategory in the sectoral volumes of this Guidebook. However, these methods generally require more extensive resources for data collection and calculation, so it may not be feasible to use most rigorous method for every category of emissions. It is, therefore, good practice to identify and prioritise the effort on those categories which make the greatest contribution to the overall inventory estimates and where possible, the uncertainty in order to make the most efficient use of available resources. It is also important to identify categories that contribute significantly to the national totals to ensure that they are compiled accurately and that the data needed to update their estimates is sufficiently maintained. It is good practice for each country to identify its national key categories in a systematic and objective manner. By identifying these key categories in the national inventory, inventory compilers can prioritise their efforts and improve their overall estimates.