The opening is the most dynamic part of the building's outer envelope, which simultaneously acts as a receiver that lets solar energy into the space and as protection against external influences and heat loss. In aesthetic terms, aluminum windows are thinner and more elegant, easily shaped into different sizes and shapes, and are available in almost all shades and colors.
Total losses through windows amount to 50% of the building's heat losses, which are usually ten times greater than those through walls, so it is clear how important the energy efficiency of openings is in the overall energy needs of a building.
Particular attention should be paid to the following items:
- Multi-layer glazing,
- Instead of air as an insulator, the space between the panes can be filled with the inert gas argon, which increases the efficiency of the window,
- Low-e coating that prevents heat loss,
- Heat loss occurs both through the glass and through the window frame,
- Total heat transfer coefficient Uw < 1.4 W/m2K.
From the requirement to reduce energy losses, through external walls, windows and doors, FEAL has developed a whole series of energy efficient systems: Termo 85, Termo 85 PA, Termo 75 DA, Inowa, Termo 150, Termo 200 DA.
European legislation prescribes lower and lower values, and today they are most often in the range Uw = 1.4-1.8 W/m2K, and even lower Uw < 1.4 W/m2K is recommended. Modern buildings require the conditions of the so-called passive house, where this coefficient Uw ≤ 0.80 W/m2K. Window profiles also contribute to the total heat loss of windows, which, regardless of the type of material they are made of, must ensure: good sealing, interrupted thermal bridges in the profile, easy opening and a low heat transfer coefficient.
English (UK) 
Hrvatski