The actual commonly used standards that determine the necessary ventilation air volume are based on fixed air exchange rates regarding different comfort levels of buildings and directly do not take into consideration that ventilation is necessary to provide certain IAQ parameters. However it would be advisable to determine the optimal ventilation air volume for each case individually considering the type of building and necessary IAQ parameters to obtain the minimal necessary ventilation volume that still provides adequate IAQ. This would ensure that the ventilation system would consume the minimal amount of energy. In this doctoral thesis a new mathematical calculation methodology that allows to predict dynamically changing indoor air quality parameters and determine the optimal ventilation air volume was developed. It is based on the characteristics of outdoor air, indoor pollutants, building volume and the rate of air exchange. Measurements of indoor air quality parameters in office and residential buildings are done as part of the job to determine the accuracy of established methodology by comparing the theoretical expectations with those actually measured. Additionally measurements of indoor moisture generation rates due to household activities are presented. The obtained results showed that the proposed method is usable for accurate prediction of CO2 concentration while for determining the dynamically changing relative humidity level the method needs to be adjusted depending on the building type taking into account the humidity absorption/desorption in the building elements. Some of the potential practical applications of work include the possibility for designers to use presented methodology in choosing the optimal ventilation air volume which is necessary to obtain certain IAQ parameters while minimizing the energy consumption as well as gives possibility for building managers to use provided methods to predict indoor air parameters for buildings. The Doctoral thesis is written in English and contains introduction, 4 chapters, conclusions, references, 48 figures and illustrations for a total of 96 pages. Bibliography lists 90 references. The results of doctoral thesis have been reported in 16 international scientific conferences and published in 20 scientific publications.