This paper describes a comparison of a family house in the adriatic and continental part of Croatia. This house, like all new buildings, must be nearly zero energy building, which would mean that it has high energy efficiency, so the need for heating and cooling is less. The required energy used should be mostly covered from renewable energy sources as is shown in this paper through solar collectors, photovoltaic modules and heat pumps. In addition to the comparison in two cities, a comparison of three thermotechnical systems and the selection of the optimal solution is also presented. All three variants of the system were implemented in the computer program "KI-expert Plus" for Zagreb and Split. With the obtained results and techno-economic analysis, it is possible to choose the most acceptable variant in terms of price and efficiency. The three variants of the thermotechnical system are: • Variant I - condensing boiler for heating and DHW preparation with a capacity of 18 kW in combination with underfloor heating, multi-split cooling system and solar system • Variant II - ground-to-water heat pump with underfloor heating and fan coil units for cooling and reheating and DHW preparation • Variant III - air-to-water heat pump with underfloor heating and fan coil units for cooling and reheating, as well as DHW preparation and photovoltaic system. The selected optimal variant of the system is variant I with a condensing boiler.