The habitable volumes of HERMES ate the capsule, the mid-fuselage cabin, the airlock and possibly a further compartment in the cone-shaped adapter. During launch, re-entry and on-ground waiting these volumes are subjected to strongly transient thermal boundary conditions. Compared to the configuration of the SHUTTLE the situation in HERMES needs a considerably higher effort in the area of thermal control performance analysis: HERMES has a higher surface area to mass ratio and the structure of HERMES will be subjected to higher temperatures during re-entry.To assess the thermal control problems of the habitable volumes of HERMES, a lumped parameter model using ESATAN comprising all thermally active components and assemblies within the pressurized volumes, all relevant structural and equipment heat capacities as well as all thermally relevant interfaces was constructed. The model is being used within the HERMES ECLSS project to provide thermal interface data for ECLSS assemblies, to define and optimize the thermal control baseline, to analyze air temperature control problems and to study the impact of various design changes on the overall heat rejection to the active thermal control system. The results shown include the transient temperatures and heat flaxes for a nominal re-entry and post-landing and two steady state on orbit results.