This presentation is intended to open technical discussions at the workshop devoted to fire testing and modelling with regard to the specificity of the fire hazard in various enclosures that are liable to drive the fire scenario (tunnels, warehouses, technical rooms, underground structures). More particularly, the paper outlines INERIS views on the role that can be played by fire tests, from lab-scale to real scale, at the light of a brief historical review and from its own experience. The purpose is illustrated by a number of examples where INERIS has contributed to analyse or solve fire problems, evaluate fire protection systems or potential consequences to the environment or more generally understand related phenomena that can be encountered in closed structures. Eventually, the paper stresses the opportunity and advantages from conjugated use of testing and modelling techniques.