Air movements initiated by temperature differences or wind exert an influence on the attic floor and may, in practice, have a decisive effect on its thermal insulation performance. The practical significance and magnitude of the effect due to convection (natural and forced) on the thermal resistance of the attic floor are studied. This article presents the measurement and calculation results of the project. A numerical and experimental study is performed to analyse the influence of natural and forced convection on heat transfer in a composite system comprising a porous material heated from below and an air space above. The numerical model is verified by conducting a number of experiments, with exapdned plastics pellets, mineral wool and cellulose as the porous medium. The agreement between the modeling and experiments, is ,in general, good.
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