Numerical and experimental investigations on turbulent natural air convection coupled with thermal radiation have been performed in a vertical rectangular channel with one-sided heated wall. A radiation model has been developed with two new features : an analytical method for computing the view factor and the macro-elements method for improving the numerical efficiency. Numerical studies have shown that the CFD code FLUTAN combined with the radiation model developed is an efficient and accurate numerical tool to investigate the flow and heat transfer behaviour in systems considered. It has shown that at intermediate and high wall emissivities thermal radiation contributes significantly to the total heat transfer by natural air conviction, even at low temperatures of the heated wall. Based on the experimental and numerical results the following semi-empirical correlation has bene developed for describing the heat transfer of turbulent natural convection coupled with thermal radiation in a vertical, rectangular channel with one-sided heated wall:Nu(t) = 0.1.Ra-1/3{1+(1+2.l)0.919.R-s/1+0.513.R-s}.