A general formulation based on the zone method is presented for the calculation of radiative heat transfer in the convective section of a utility boiler. Several simplifications are made to derive a simplified formulation and an engineering model suitable for practical engineering calculations. it is shown that the simplified formulation and the proposed engineering model yield very similar results. The role of the average mean beam length is investigated, along with the influence of the emissivity and temperature of the boundaries on the predicted absorbed radiative energy in the tube banks.