The ARD capsule is a European Space Agency project, designed and developed in very limited budget and schedule. These constraints had induced a particular strategy for Thermal Architecture activities: to decouple Thermal Protections Subsystem activities and Internal Thermal Control activities. The necessary relationships between the two fields have been achieved through interfaces data exchanges. These exchanges have been managed to guarantee the Vehicle Thermal Architecture coherence and to avoid risky conditions at system level.The consequence is important margins on the thermal design of the capsule. This is possible on this type of prototype where optimization is not required. Extension of such a process has to be considered cautiously.