The article presents results of simulation of building assuming presence of phase change material in wall barriers. Obtained results were compared with the ones of a building without phase change material in wall barriers. Object of comparing calculations is a model of a real service building located in Silesia. It has light-frame construction with light covering (external metal sheet, heat-insulation, interior metal sheet). In subsequent examinations, the presence of 1 cm thick PCM board placed under the inner surface of a metal sheet was assumed. Tests were conducted for organic materials that undergo phase transition in different temperatures such as 23°C, 25°C, 27°C or 29°C. Based on results of operative temperature measurements, it is possible to determine PCM influence on the building overheating risk.