The apartment building is located at the address of the Istrian passage 11, 51 500 Krk, which was built in 1800. The object is inadequate structural elements in terms of energy efficiency. The reconstruction of the facility and the installation of a high-efficiency heating and cooling system for the beneficiary will contribute to reducing annual primary energy consumption in the building (administrative building), improving user performance and reducing operating costs. The facility is planned to implement energy efficiency measures by installing thermal insulation on internal walls, hairs and replacing the existing joinery with a new one, which will lead to significant savings in the energy consumption Qh, nd 40 422.55 kWh/a (52.72 %).