Conclusions of the study

Having analysed all the factors that influence the energy efficiency of windows, and the way in which they modify the consumption of buildings, the following conclusions can be drawn:

• It is decisive for energy efficiency to choose a glass with a solar factor that is appropriate for the location of the windows, taking into account both the climate zone in which they will be located and the orientation of the building itself.
• The air permeability of the window will determine the energy consumption and comfort inside the building, so it is necessary to choose a material that guarantees that this performance will be maintained over time.
• The thermal transmittance of the profiles supporting the window has a very small effect on the final energy consumption, the glass being the determining factor in this aspect.
• The replacement of aged windows with low thermal resistance and low air permeability by windows with aluminium frames with RPT favours energy savings, improves comfort and improves the energy rating of existing buildings.