All of the fundamental work of the NFI, from data collection, to data processing and evaluation, to publication of the data, is performed as part of the core module. This module also includes all logistics, e.g. operation planning, field computer programming, and maintenance of the databases and the NAFIDAS statistical analysis system. The core module is therefore the largest module of the NFI. The specialised modules (e.g. greenhouse gas inventory) use the services of the core module and build on them.
The NFI is continuously developing its methods. To this end, it conducts research in areas such as inventory statistics, remote sensing and GIS. It also regularly conducts requirements analyses and undergoes evaluation by a third party.