Renewable technologies and the extension of their scope of usage basically has to face the general obstacles like any other novelties newly introduced to the market. In the case of environmentally friendly and clean technologies we must consider another critical aspect: the knowledge and the trust of the potential future users. To influence these people first we must extend their knowledge regarding renewable energies so they will be able to change their own approach about them. Usually the most crucial factor is the economic efficiency which determines the attitude of the majority of the users. Even the ones whose decision making process is highly based on the environmental patterns. In the case of any technology, the economic aspect is significantly influenced by its operational effectiveness. So this analysis – besides the direct economic matters – aims to examine how the performance of thermal water heating in greenhouses can be improved by using heat pumping.