An algorithm of an electronic monitoring system performance for evaluating the overall heat transfer coefficient has been developed. It uses a model which describes the energy exchange in an animal farm building. The finite difference method has been applied in the modeling process. The input signals of the model are measured in real time values of the building parameters. Based on the algorithm, a software product has been developed to predict the temperature and the air relative humidity variations inside the building. A structural scheme of an electronic monitoring system for evaluating the overall heat transfer coefficient has been created.