Indoor Air Quality (IAQ) assurance is done mainly through the air exchange between interior and exterior. Lack of adequate ventilation of indoor spaces causes poor air quality and a higher incidence of sick building syndrome (SBS), which is manifested by affecting the comfort and wellbeing in the indoor spaces. Ensuring high energy performance buildings and indoor air quality is efficiently approached by limiting emissions from sources, by partial neutralization of the pollutants or by smarter ventilation. The concept of smart ventilation was developed to ventilate properly while reducing energy loads, allow for the provision of grid services, and promote associated renewable power integration. The above-mentioned information can be obtained by the air quality modelling, using mathematical approaches to predict the way pollutants behave in a certain environment or time scale. The paper presents the results obtained by mathematical modelling of indoor air quality, by including the transfer of pollutants from external sources and variable indoor emissions. The considered pollutants are ozone (O3), particulate matter (PM2.5), formaldehyde (HCHO) and carbon dioxide (CO2), due to the significant adverse effects on human health and their different preponderantly sources: indoor, outdoor or both indoor and outdoor. The main goal of our researches is the reducing of the amount of energy that ventilation uses while maintaining or improving IAQ.