The aim of the thesis was to develop a project of forced ventilation of the public library premises. The library is part of new building situated on Ružinovská street in Bratislava. The library premises are located on two above-ground floors. It is an open space with two galleries, three glazed walls in the east, south and west, creating very airy space. The air handling unit meets the requirements for the microclimate parameters in the library and for the demanded multiplicity of the air exchange. It also brings in the outdoor air which is to be adjusted (filtered, cooled or heated) before its entry into the room. The air handling unit will be located in the air-conditioning machine room in the basement.