Exactly. We often hear: 4-chamber, 5-chamber, 8-chamber profiles…. What does that mean in practice? How much marketing is there in these chambers, how much air and how much of an actual value to the user? Here is a bunch of facts.

A good (multi-chamber) profile is the basics

A PVC profile is the basic and most important element of a window construction. The window profiles contain air chambers inside them. These air chambers are decisive to the PVC window’s thermal insulation values. They determine its thermal transmittance coefficient. For example: for a window built with a 4-chamber profile the Uw coefficient can be 1,8-2,0 W/m2K, and for a window made with a 7-chamber profile circa 0,8-0,9 W/m2K.

This comparison shows, that a multi-chamber construction of the window profiles improves their thermal insulation values.


The more chambers the more possibilities to set steel profiles inside the window profile. They determine the rigidity of a PVC window. Therefore, it is a good practice to check the number and thickness of steel profiles in windows of a specific manufacturer. Many manufacturers decrease their number and thickness in a PVC profile, from which windows are made, due to steel prices. It has its consequences in the rigidity and, thus, the longevity of a window.

Expert’s commentary

The number of air chambers in a window profile determines the thermal transmittance coefficient Uw. The more chambers there are in a profile, 5,6 or 7, the lower the value of the thermal transmittance coefficient, which ensures a lower heat loss. Except of the number of the air chambers itself, their width and the thickness of a profile’s inner and outer walls is also important. For example, the Schüco systems and the ‘4 seasons’ windows produced of them come in versions with 5,6 and 7-chamber profiles, which provide a very good thermal insulation. In practice this means lower heating costs and a better window rigidity.

Przemysław Kasperski– Production Manager