摘要： Limiting junction temperature Tj and maintaining its low value is crucial for the lifetime and reliability of semi-conductive light sources. Obtaining the lowest possible temperature of Tj is especially important in the case of LED panels, where in a short distance there are many light sources installed, between which there occurs mutual thermal coupling. The article presents results of simulation studies connected with the in?uence of construction and ambient factors that in?uence the value of junction temperature of exemplary LED panel sources. The in?uence of radiator’s construction, printed circuit boards, as well as the in?uence of ambient factors, such as ambient temperature Ta and air ?ow velocity v were subjected to the analysis. Numerical calculations were done in the FloEFD software of the Mentor Graphics company, which is based on computational ?uid dynamics (CFD). For construction of the LED thermal panel model the optical e?ciency ηo and real thermal resistance Rthj-c were determined in a laboratory for the applied light sources.