Surface radiation with conduction and convection in a heated two-floor enclosure is investigated experimentally and theoretically. A model based on the net-radiation method is employed to compute the radiation exchange between the surfaces including the heater surfaces. The radiation model assumes opaque, diffuse and gray surfaces, a nonparticipating medium, and uniform radiation fluxes and temperature. The view factors are obtained by using the reciprocity relations and numerical integration. The wall heat transfer rates by radiation, convection, and conduction were computed for the closed and open enclosures and for two different heat input rates of 300 W and 600 W. An experimental study was carried out to measure the internal and external surface temperatures of the walls, surface temperatures of the heater, and air temperatures. These temperatures were used in the calculations. The special emphasis is given to the effect of through-flow on the wall heat transfer mechanism. The results show that the effect of through-flow on the wall heat transfer is significant. Also, the results indicate that the heat transfer from or to the enclosure walls is mainly by convection. However, as a result of the heater position, the energy exchange by radiation becomes significant for the lower compartment walls. (C) 2000 Elsevier Science S.A. All rights reserved.