For the energy system of the house, three possible versions of the thermotechnical system have been developed which differ by the heat generator (source) and cooling system. The house is a ground floor house located in Zagreb with total net floor heating area 119.54 m2 . Adopted technical system of the house exploits the heat of the deep layers of the earth to heat the house and prepare domestic hot water. The reversible operation of the heat pump in the summer returns the thermal energy to the deep layers of the earth, by which the soil regeneration is done. Panel floor heating and a tubular bathroom radiator were adopted as the heating bodies, on the other hand fan coils were used as cooling bodies. The selected heat pump has a built-in DHW cylinder of 220 l, electric water heater, diverter valve, circulation pumps of the primary and secondary circuit and digital regulation (with the rest of the equipment – two heat inverters, connecting line, compressor and throttle valve). An inertial water tank with a capacity of 200 l was built into the heating and cooling system. Mechanical ventilation enables continuous indoor air exchange in order to maintain the necessary hygienic conditions and save energy by using a recuperator (plate heat exchanger) for the heat recovery of the exhaust air. The photovoltaic module generates electricity intended to cover electrical energy consumption of the house in order to achieve the lowest possible primary energy consumption. Residual energy required for the operation of such a system is supplied from the public electricity network. The project was made according to the valid norms and the Technical regulation of rational use of energy and heat protection in buildings.