1966-1996 Hamm-Westtünnen
1969-1984 Norderney in north sea
1969-1986 Essen/Ruhr area
1969-1986 Essen/Ruhr area
1969-1986. Seventeen years in Essen/Ruhr area
The first Scientfic Evidence that KÖMMERLING U-PVC window can last longer than a lifetime.

The reason why the old wooden window on the first floor in a shoe shop in Essen were replaced with KÖMMERLING U-PVC windows in 1969 are quite surprising: the need for improved heat insulation. That sounds very topical to us today , although the U-PVC windows were of the earliest type .
Certainly there was a shift away from the use of wood as a reinforcement for the profile, glazing system were changing, and fitting s were of a different design. System engineering was becoming increasingly important. The initial Scientific tests of an old type of KÖMMERLING window produced spectacular findings: despite it's age in 1986 it still met all the current requirements with regard to it's functions, stability and fittings.

Thus not only had the retained it's advantages over the past 17 years but certain requirements that were only introduced later had also been anticipated and applied.

Window that last as long as the building themselves
What the inhabitants of Essen have to endure has provided to be an advantage for the long term tests of KÖMMERLING windows. if such environmental pollution fails to have any negative impact after two decades, the life of such windows can be assumed to be at least equivalent to advantage life of a building, i.e. 60-80 years.

Color as new, Both inside and out
The inside and outside of the window were cleaned in the laboratory. To enable a better comparison to be made, the untreated areas were covered. On both the inside and outside, the cleaned areas were as good as new. In addition, an assessment of the weather-fastness according to RAL, using a gray scale, showed no significant discrepancies.

17 years without repairs or maintenance
A two-piece horizontally pivoted, tilt-and-turn window on the first floor of a building situated on a main road was chosen. Apart from slight wear on sash around the fittings, the tested window fulfilled it's designated function perfectly, and could be easily opened, moved and closed.
  Examination reveals no changes
No yellowing, graying or other changes to the surface were detectable with the naked eye, so a reflected light stereo microscope with 120 x magnification was used to examine the test piece. Once again no relevant changes to the surface could be seen that would indicate a negative impact on material

All mechanical functions correct
On -site examination by experts also demonstrated that the window was fully functional. The owner reported to the compilers of the experts' report that no repairs had been seen necessary during the previous seventeen years, nor had any maintenance work been carried out on the KÖMMERLING U-PVC profile of the test window.

  Perfect even after pollution tests
Microscopic examinations revealed the external traces of 17 years of atmospheric pollution of material acting on the surface of profiles, but no changes could be found. Heating of test pieces had no effect on them either, and no blistering or cracking occurred. The relative longitudinal change was less than the allowed figure stated in the RAL directive