Numerical and experimental thermal analysis for the improvement of various types of windows frames and rolling-shutter boxes.

Data provided by the Italian Ministry of the Environment say that in five years you consume, just for heating of an apartment, an amount of energy equal to that required for the all construction of the same apartment. The years come down to three if one includes other energy consumption. In terms of primary energy, by summing production and management, the building-plant system is responsible for about 45% of the national energy demand. The rolling-shutter box system, in most cases, is the first responsible for both the thermal dispersions that the input of free heat coming from outside. In addition, the window frames have the obligation of the CE marking to be sold on the free European market. The CE marking confirms that the finished product is able to provide certain performance, relative to the intended uses, according to regulatory requirements. Among the basic requirements, the thermal transmittance is the parameter responsible for the energy performance. The research carried out concerned the energy study of different window frames and rolling-shutter boxes through the use of finite element methodology and experiments in situ. The study was carried out on six different types of windows frames (PVC, wood and wood-aluminum) and four different models of rolling shutters-boxes (all with structure made by expanded polystyrene EPS). The experimental analysis allowed the comparison between the thermal transmittance values calculated according to the UNI EN ISO 10077-1/2 and measured in accordance with ISO 9869. The two results returned a difference in the transmittance values less than 5%. Subsequently, through the finite element analysis it was possible to verify the trend of temperatures and heat flows in the window frame and rolling shutters-box. From analysis we deduced that the best window frame system has a transmittance of 1.122 W/m²K and the best rolling shutters-box system a transmittance of 0.703 W/m²K. The last phase of the study regarded the design of some improvement solutions, both for the window frame and the rolling shutters-box. The hypothesis of improvement was made on two frame systems (PVC and wood) and four rolling shutters-box systems. Taking as an example the previous best systems, the following improvements in terms of percentage in the value of the thermal transmittance were reached: the frame achieved an improvement of 10%, while the rolling shutters-box an improvement of 37%.