Effects of window replacement on energy renovation of residential buildings - case of the Serbian building practice

Achieving the desired degree of energy efficiency in buildings has become an imperative of nowadays construction.This requirement is set in relation to both new and existing buildings, in order to reduce their energy consumption, but also to improve the overall comfort, especially thermal, contributing in this way to a creation of a healthier place. Measures that are applied in order to improve energy efficiency in buildings include various interventions on its thermal envelope, which in the case of energy renovation of existing residential buildings is not necessarily all-inclusive.The effectiveness of the measures implemented to assess the appropriate calculation methodology of the energy required for heating, as in the case of existing regulations in Serbia, implies that applied enhancement should contribute to the improvement of their energy class for at least one energy rate. Such improvement, especially in the case of larger buildings, could be achieved only by improving the air-tightness of the existing windows, but their replacement with windows of high energy performances is the most common measure in practice. However, without energy rehabilitation of surrounding façade walls, such intervention could cause condensation along the peripheral, insufficiently insulated, non-transparent structures. Thus, the positive effects of the improvement measures could be questioned. Taking into account the characteristics of the existing building stock in Serbia, typical situations of existing contacts between the façade walls and the corresponding windows are simulated in the paper, in relation to the risk of condensation and consequent potential users’ health problems