Demands for more energy efficient and economically advantageous ways of heating and cooling the space in which we live and work are becoming more pronounced. Legislation is gradually imposing an increasing use of renewable energy sources. Free interior design regardless of the position of the heating and cooling devices is also a common desire of architects and designers. In response to these requirements, various forms of surface heating and cooling has been developed. They are installed on floors, ceilings and walls. A new surface-like system was developed in the early 1990s. The main difference compared to surface-like systems is in the location of the pipes, namely in this system the pipes for conducting hot or cold water are placed inside the load-bearing concrete slabs or walls itself. This changes the whole concept of heating and cooling. Any heating or cooling bodies and pipes for water or air conduction are discharged from the room. So the pipes are hidden inside the slab itself which serves to emit the necessary heat or receive its excess. The system is called concrete core activation or thermally-active building system. Thermally-active building system is based on pipes that conduct hot or cold water inside the concrete slab and thus heat or cool the concrete mass that transfers the accumulated heat to the room or removes it from it. In this way, a comfortable room temperature is ensured in the room throughout the year without the feeling of drafts, unnecessary noise and the appearance of moisture. Since it works at temperatures close to room temperature, it is suitable for working with heat pumps and energy-renewable energy sources. This thesis presents the properties of the system, the principle of operation, construction methods, application, its advantages and disadvantages. Finally, a comparison of the costs of installing a system for thermal activation of the concrete core with the costs of underfloor and radiator heating is made.