As shown by the figures below, Semco Glastechnik GmbH and Scheuten Glasgroep BV succeeded in developing a new layer stack, which properties are almost unchanged by heat treatment at temperatures above 600°C. The colour shift induced by the high temperature process is quite low and can be tuned such, that tempered and untempered coatings may be mounted into a fassade adjacent to each other without a visible colour difference.
Furthermore the reduction of the film emissivity by more than 30% means a strong improvement of films properties by the high temperature process. The coating emissivity drops from 4 % to 3 %after tempering.
This fact allows using this coating together with untempered 3% emissivity coatings, which is the new generation of low-e coatings. For these reasons, the developed coating provides high potentials on the market, to be used as a 4 %-emissivity coating without heat treatment or as a 3 % - coating after heat treatment in one fassade.
In the following, the data for a double-glazing with this coating before and after heat treatment are summarized.
Before After high temperature process
Light transmission(D 65) %: 80,2 81,6
Energy transmission EN 410: 66 64,5
b-value (transmission): 2,07 2,4
a-value (transmission): -1,4 -1,1
b-value(reflection glass): -6,7 -11,1
a-value(reflection glass): -1,9 -0,4
b-value(reflection film): -9,1 -12,1
a-value(reflection film): -1,0 0,1
Emissivity: 4,5% 3%
Haze: 0 0,06
Leaving away a certain layer within the stack we could reduce the colour shift, especially the b-shift strongly from about 4 to 2,5 only.
With these results it should be even possible to place the untempered und tempered product adjacent to each other in one facade without a visible colour shift.