The studies described in the present paper have been developed by the teams involved in the French National Research Programm "ARC Convection Naturelle dans l'Habitat" coordinated by CNRS-PIRSEM (Inte disciplinary Research Programm on Energy and Materials, National Scientific Reseach Center) and suported by AFME (French Agency for Energy Management). After a short description of the experimental facilities of each laboratory, we give some significant results on high Rayleigh number natural convection in rooms.

Mass transfer due to pressure-driven air flow is one of the most important processes for determining both environmental quality and energy requirements in buildings. Heat, moisture, and contaminants are all transported by air movement between indoors and outdoors as well as between different zones within a building. Measurement of these air flows are critical to understanding the performance of buildings. Virtually all measurements of ventilation are made using the dilution of a tracer gas. The vast ma,jority of such measurements have been made in a single zone, using a single tracer gas.