Jobbágy J., Krištof K., Andacký M. (2016): The effectiveness of heating of housing unit by renewable energy source. Res. Agr. Eng., 62 (Special Issue): S34-S43.The paper is aimed at pointing out possibilities of using of dendromass for heating. The object of interest was heating of housing units with 75.27 m 2 of total area. The average value of dendromass moisture was 17.71%. The inserted fireplace Nordica Focolare 70 with a nominal output of 9 kW was used as a heat source. For temperature measurement, a non-contact infrared thermometer GM 900 was used. The total heat loss transferred through walls of housing unit (heat loss through thermal bridges and ventilation losses) were calculated at the value of 176.26 W/K. Based on the results of samples moisture the net calorific value of one kilogram of burned fuel wood was determined (14.791 MJ kg). The amount of thermal energy which is necessary to supply by the heating system for the whole heating period was 14,199.18 kWh. The weight of raw fuel wood was 5,450.97 kg (at moisture of 30%), dried at 17.71% (4,636.87 kg). Price of raw fuel wood of acacia for the year under evaluation was 64.80 €/m 3 (the required amount of raw fuel wood for heating period was 10 m 3 ). Total costs for the heating season was thus 648 €. The price of heat transmitted by the fireplace inset Nordica Focolare 70 inserted into heating system using fuel wood (white acacia) with 17.71% of absolute moisture was 0.045636 €/kWh.