Building’s energy efficiency is already significantly determined at an early design stage of an architectural-constructive part. It is important already at that stage to select in terms of energy and daylighting effective glazing. In this paper, influence of the building’s glazing characteristics on its primary energy demand is evaluated in a complex way, performing simulations of the annual energy demand sub hourly. Results show that in cool climate zone, to which Lithuania belongs, it is possible to decrease building’s microclimate and lighting systems’ energy demand to the level of low energy office building just with the selection of the efficient glazing characteristics. At the same time minimal requirements for daylighting are satisfied
