The introduction of renewable energy resources (RES) in the European energy systems can contribute to the achievement of the goal of the European Green Deal - climate neutrality by 2050. The study analyzes the possibility of using the existing infrastructure of oil terminals to improve the heating/cooling system of the building with RES integration. The energy efficiency of the developed energy supply system was evaluated with dynamic simulations using the TRNSYS 18 software. The aim of the analysis was to choose the most energy-efficient solutions for the design of the building heating/cooling system using RES and to reduce the system costs as much as possible by using the already existing water tank. It was concluded that the developed system can increase energy efficiency. Almost 49% of the building's heat energy and 66% of the cooling loads can be provided by the heat pump and thereby CO2 emissions can be reduced. The contribution of this research is that its results can be used for European climate and energy goals achievement by adapting the existing infrastructure to RES-based energy supply system solutions.