Energy consumption of a building is defined as the amount of energy (e.g. thermal, electric) supplied to the building from the outside in connection with a proper building operation during a year. It is determined by means of different indicators expressed in kWh (m2·year): applied energy indicator (EU), final energy indicator (EK), and in power engineering characteristics certificates buildings are evaluated in relation to non-renewable primary energy (EP). The majority of consumers think that energy consumption depends on a heating system, therefore, they focus only on looking for a modern and low-maintenance system that produces heat for the needs of a central heating and hot service water. Shaping an energy efficient building (of low energy consumption) is a complex process, in which one is to take into consideration various elements that impact the amount of energy that has been consumed. Simultaneously, building structures should be constructed in order to utilize them comfortably by providing adequate microclimate parameters of the interior. This thesis presents an analysis of the impact of physical parameters of external wall barriers and their joints, and a ventilation system on energy consumption of a building.