The energy saving properi es of an exisi ng solar collector investment has been assessed based on factual data and stai si cal methods. The seasonality of electricity, water and gas consumpi on has been determined. The number of guest nights, the electricity and gas consumpi on showed a strong and a moderate correlai on. The costs saved did not live up to the expectai ons, which makes the return indicators signifi cantly worse. The discrepancy may be due to the system being designed to be bigger than reasonable or the great energy loss as well. The lat er may be because of the distance between the collectors and the hot water containers. The system may have calibrai on problems as well. The whole area brings about saving an amount of energy that equals to HUF 851000, which translates into 8788 m3 of natural gas. The decrease of CO2 emission should come to 16.26 t. on an annual average.