  The first purpose of our work has been to allow -as far as heat transfer
modes, airflow calculation and meteorological data reconstitution are
concerned- the integration of diverse interchangeable physical models in a
single software tool for professional use, CODYRUN. The designer's objectives,
precision requested and calculation time consideration, lead us to design a
structure accepting selective use of models, taking into account multizone
description and airflow patterns. With a building case study in Reunion Island,
we first analyse the sensibility of the thermal model to diffuse radiation
reconstitution on tilted surfaces. Then, a realistic balance between precision
required and calculation time leads us to select detailed models for the zone
of main interest, but to choose simplified models for the other zones.
