Thermal aspects take place in several industrial applications in which Electricite de France (EdF) is concerned. In most cases, several physical phenomena like conduction, radiation and convection are involved in thermal transfers. The aim of this paper is to present a numerical tool adapted to industrial configurations and which uses the coupling between fluid convection (resolved with ESTET in finite-volumes or with N3S in finite-elements) and radiant heat transfers between walls (resolved with SYRTHES using a radiosity method). SYRTHES manages the different thermal exchanges that can occur between fluid and solid domains thanks to an explicit iterative method. An extension of SYRTHES has been developed which allows to take into account simultaneously several fluid codes using `message passing` computer tools like Parallel Virtual Machine (PVM) and the code coupling software CALCIUM developed by the Direction of Studies and Researches (DER) of EdF. Various examples illustrate the interest of such a numerical tool. (J.S.) 12 refs.