The thermoradiational situation in the steelmaking shop and at the aluminum casting site was investigated. The calculation of the heat radiance of a steelworker and a forklift operator of metallurgical production is carried out in two ways. The first method involves the engineering calculation of heat radiation and the construction of its plot in two-dimensional and three-dimensional space, based on data on the temperatures of radiation sources, the distances from them to the irradiated objects, the angles between the normal to the sources and the directions to them and the degree of blackness of radiation sources. For a workplace located in a volume limited by walls, the degree of blackness of the wall material was additionally considered. The second method involves mathematical and computer modeling. A numerical model implemented in the ANSYS finite element modeling program was used. A mathematical model of radiation based on the Discrete Ordinates method was used to display thermal processes. When comparing the results of the calculation of heat emission by two methods, it was revealed that the relative error of the diagram calculation method in two-dimensional space compared to modeling averaged 34.9 %, in three-dimensional — 22.5 %. This is due to the fact that when calculating by the diagram method, radiation sources and irradiation objects (in a two-dimensional formulation), as well as the radiating surface of sources (in a three-dimensional formulation) are considered not as three-dimensional objects (as in modeling), but as point objects, which effects the accuracy of the method.