During this time sustainability issues arise more than ever, given the requirements imposed by European Union standards, which will apply from 2018. In this context, it becomes increasingly evident that a new design of current technologies is necessary in order to be able to meet the required thresholds regarding the economic, ecological and socio-cultural criteria. The development of modern building envelopes is already predictable, having a modular component and one that will provide the so-called  "intelligent behavior", which generally refers to the building dynamic adaptation to specific user behavior mode. In the next period, another defining element will address to universal design, which subsumes the issue of compatibility between the requirements of the beneficiaries and the capacity of the included construction systems to meet their expectations. It can be easily seen that, regardless of the period under consideration, a common element for those buildings equipped with large transparent surfaces is the great energy efficiency. Also, a problem that has been permanently in the spotlight was the sealing of the facade elements to the external environment, performing, thus, an increase of the comfort level of the users. Furthermore, one of the major challenges that contemporary experts have to solve relates to the requirements for incorporation of new technologies and functions, such as, for example, power generation, mechanical and natural ventilation, strict control of light radiation etc. Given that such requests are difficult to put into practice, the experts concluded that a strict classification of curtain walls must be imposed, identifying the following main categories: "box windows", including individual mesh window, additionally sealed from exterior through a continuous glass surfaces, secondary curtain walls, covering the entire building envelope; structural "corridor", which has the advantage of dividing floors of a building, each level benefiting - practically – from its own front curtain; axial curtain walls, providing better control functionality (the system represents, in fact, a combination of individual glazing and an insulation system vertically installed).For further information and a detailed analysis of the current TOP-Fereastra issue click here!