The energy upgrading of existing buildings. Windows and shading devices typologies for energy efficiency refurbishment.

Residential buildings built after Second World War have high energy consumption and inadequate thermal comfort, especially in summer conditions, largely attributable to high transmittance of windows and lack of effective shading devices. Performance improvement of these components is essential for energy upgrading of existing buildings. This paper shows the results of the research, under the national project PRIN 2008, "Performance of transparent components of building envelope for energy upgrading of residential buildings", which aims to evaluate effects on energy consumption and environmental comfort of combined solutions of windows and shading devices applied to existing buildings. In this paper, main typologies of windows, typical of the existing buildings, and solar control systems are described and evaluated on the basis of a case study. For each solution, in four representative climatic locations (Berlin, Milan, Florence and Athens), thermal behavior has been assessed trough EnergyPlus dynamic calculation code, by using appropriate performance indicators: Qs (solar gains), θo (operative temperature), F (reduction factor of solar gains). Starting from performance evaluation of the existing building, different strategies have been assessed: replacement of existing windows with high-energy performance ones and introduction of shading devices and solar control glasses. Finally a comprehensive evaluation of the aspects of energy consumption, natural lighting, acoustic comfort, and technical feasibility is carried out.