Sustainable urban planning is vital for energy efficient districts, involving renewable energy integration and technologies to enhance sustainability. The integration of innovative technologies plays a crucial role in sustainable urban development. Smart energy systems, IoT devices, and data analytics enable efficient resource management and support environmental conservation efforts. Slovakia, as EU member, is also committed to gradually reduce the use of fossil fuels and to introduce more renewable resources into energy system. The current state of energy consumption is later analyzed using the example of a part of the city of Zilina. Subsequently, a building renovation scenario is proposed for the selected city district, while possible energy savings are calculated. In the final part, the use of photovoltaic panels and a heat pump is compared, while the regulation is provided by smart home management.