This Master’s Thesis deals with the design of ventilation and cooling of an under roof flat in a tenement building, built in the 1980s, and consists of five main parts. Within the first main part, the thesis is dedicated to the research of the current state of knowledge in the area ofventilation and cooling of residential premises, secondly, there is a detailed description of a particular flat, thirdly, the calculation for the optimal design of ventilation and cooling are made and, in the fourth part, suggested solutions are proposed with the following evaluation of them including the overall summary. The design of ventilation and cooling was carried out according to the design procedures with respect to the relevant standards and optimized...