The decision to make a wall like that is due to the fact the designer wanted to reduce to minimum the energy losses in winter and this solution allows to have really low consumption of energy. The transmittance of the walls is of 0.107 W/m2K, one third lower than the limit imposed to new construction for the 2019. In addition, the slabs are well isolated to reduce the vertical heat losses, using a layer of 10cm of EPS, having a light construction with high thermal and acoustic performances.
The windows have a PVC frame to reduce thermal losses and corrosion; they are characterized by a triple layer of glass, also good from a thermal point of view. This kind of glass allows the solar light to enter the building because of the big area of the windows, it is important from a thermal point of view because there are useful solar gains in winter and the triple layer stops the heat to flow from inside to outside. In summer, the sun is higher than in winter, so we have balconies with also the function of overhangs to reduce the solar gains. The total transmittance of the windows is 0.71 W/m2K.
Analyzing the energy balance of the building is possible to say that the heat plant is almost unnecessary due to the solar gains and how they are managed. In the southern part are installed a series of horizontal fixed shading system on the balconies and on the windows to avoid overheating during summer.
It differs from the vernacular architecture because in central and south Italy there were small windows on the buildings to let the minimum light possible entering to avoid overheating in summer, instead in the new constructions it is preferable to have big windows to let the light in, to reduce the electric consumptions. The two southern faces have only the balconies, without windows on the façade, they are all protected by a wooden shading system. The wood is positioned all over the building, but in particular in the southern part because, since it is not a conductor, in summer brings benefit to the building, keeping the heat out.
The design of the envelope is useful to use a unique system for all the apartments, in fact, for the winter period, there are low energy consumptions and in summer, when the cooling is needed, the single heat pump is enough. The heat pump is a water-air type that consumes the energy produced by the photovoltaic panels and the heat produced by solar panels, so to have an energy balance that is near to zero. The design choices optimize the winter mode, but also reduces the summer needs in comparison with the old buildings. The heating system is composed by a radiant floor, instead the cooling system is only mechanical ventilation mode, and all of this can be controlled by a home automation system that has also the function of monitoring the energy balances. It is also possible to have a natural ventilation.