Thermal effects of air flows in building structures.

The thermal effects of air flows in building structures have been analyzed by computer simulation. Some laboratory experiments have also been carried out concerning natural convection in closed and semi-open cavities filled with fibrous insulating material. Three different flow systems in building structures have been studied: natural/forced convection in open/semi-open (permeable cold surface) 2-dimensional insulation structures, heating of infiltrating air in cracks and diffusive infiltration. The thermal effects of air flows are described by the Nusselt number defined as the ratio of the average heat fluxes with and without air flow (internal/penetrating convection or infiltration).