My main opinion in this thesis was to design a reversible heat pump as a source of heat and cold for an administrative building located in Bratislava. I also solved the minimal hygienic exchange of air in the office space. The design of the ventilation and air conditioning system begins by determining the boundary conditions of the building's internal environment. I continued calculating the amount of in take and exhaust air. For calculated amounts of air, I designed ended distribution elements, over-dimensioned supply and exhaust air distribution, and designed a ventilation unit to ventilate the object. In the next step, I have calculated the thermal load and thermal losses of the building. Loss and load values served for the design of internal window and cassette VRV units that will heat and cool the room. In addition to the sum of indoor unit outputs, external units were designed as heat and cold sources. In hygienic rooms, I only solved with the exhaust air which I set according to the air supply to the equipment. Removed air will be replaced by infiltration from surrounding rooms. In administrative buildings, it is very important to ensure the thermal comfort of indoor spaces, as positive and negative factors in the work environment influence behavior, moods, feelings, performance, and, last but not least, employee health.