From a set of around 30 thermosets (polycyanurates, polybenzoxazines, epoxy and phtalonitrile resins) tested in pyrolysis-combustion flow calorimetry, the contributions to flammability of 14 new chemical groups are calculated using a method previously proposed and validated. The flammability properties include total heat release, heat release capacity and char content. The comparison between these groups allows drawing some consistent conclusions about the best structures in terms of flammability. Especially, the aromaticity, the number of covalent bonds between the considered chemical group and the neighboring groups and the presence of heteroatoms (O, N) in the structure are highlighted.