In this thesis, the energy system of a family house is dimensioned. Heat losses are calculated according to HRN EN 12 831, and heat gains according to VDI 2078. Analyzing the results, we see that the heat losses and gains are very large due to the poor thermal insulation of the family house. A price comparison of different renewable energy sources was made and it was concluded that the most cost-effective system is the one with a heat pump. A geothermal heat pump with a collector field was chosen as the only heating, cooling and DHW preparation system. Fan convectors are used as indoor units for heating and cooling. When choosing a solar power plant, it was taken into account that it covers all the annual electricity consumption. We obtained the annual consumption of electricity by looking at the bills for the past year, and using the calculation we chose a power plant with a power of 3 kW. By choosing a biodigester, we eliminate the need for the removal of biowaste that we use for the production of biogas and liquid fertilizer. This method reduces the need for removal by the utility company and the need to purchase gas used for cooking. By using already installed wells to collect rainwater, the family house is supplied with enough clean water for food and hygiene needs throughout the year, and refilling with city water is only necessary in case of extreme droughts during the summer months.