Enthalpy calculation for a part of my system

GROMACS version: 2020.5
GROMACS modification: No
Hi,
I am working on a peptide /membrane system and i know that we could get the enthalpy of the system by ‘gmx energy’ i would like to know if there’s a way to calculate the enthalpy for the binding of the peptide to the membrane (could it be related to ‘-rerun’ option ? )

Thanks in advance