  This article presents the CODYRUN software developped by University of La
R\'eunion. It is a multizone thermal software, with detailled airflow and
humidity transfer calculations. One of its specific aspects is that it
constitutes a research tool, a design tool used by the lab and professionnals
and also a teaching tool. After a presentation of the multiple model aspect,
some details of the tree modules associated to physical phenomenons are given.
Elements of validation are exposed in next paraghaph, and then a few details of
the front end.
