The TSR test method. More efficiency and durability in window construction.

Developing novel surface finishes also depends on fresh ideas in terms of proving practicality. skai® relies on an innovative test method for the development of its window profile films, which can measure and predict thermal behavior under solar radiation in the laboratory more precisely than ever before: The TSR test method. The skai® cool colors and cool colors plus films were also tested with this method.

Window profile films – the cooler they are, the longer they last

Window and door profiles have a tough job. Rain and snow, wind and sun – they all have to be fended off for decades. Heat in particular is giving window profiles more and more to do even in temperate regions. The more their surface heats up, the higher the risk of mechanical product failures: windows expand due to heat and then no longer close properly.

Conversely, lower temperature stress greatly improves the durability of a window profile. Even an average temperature lower by 5 °C extends service life by as much as 50%.

Test method: How do we get the sun into the laboratory?

To keep plastic windows cool in the sunshine, we have been working in the laboratory for years on outdoor profile films which reflect as much solar radiation as possible. To check the reflective behavior of profile films, coated plastic profiles have always been examined in the laboratory using special processes. So far, these laboratory tests have been carried out according to the so-called “heat build-up” method. The problem is that the infrared lamps used for this purpose do not mimic sunlight sufficiently closely. Outdoor experiments often revealed different, sometimes even contradictory, temperatures.

Photo: Heat Build-Up process

The TSR method measures radiation reflection realistically

We searched for a more reliable test method for a long time and finally found the TSR test method (TSR = Total Solar Reflection). It exposes window profile films to radiation of a wide variety of wavelengths in a spectrometer. And in fact it uses exactly the wavelength responsible for the heat, from infrared to red, yellow, green and blue to ultraviolet. The TSR value measured indicates the percentage of the total radiation reflected from the surface. So the higher the TSR value, the less the material heats up.

Precise heating behavior predictions are possible

The special feature of the TSR value is that it allows prediction of the heating behavior of a surface under a wide variety of conditions. Hundreds of external measurements have shown that there is a mathematical correlation between solar radiation, TSR value and measured surface temperature. What’s more, if you know the TSR value of a film and the temperature behavior of a white and black color composition, you can also make exact temperature predictions for all shades of gray in between!

Heat-free as the standard: skai® cool colors and cool colors plus

Measurements from the TSR method show that skai® cool colors and cool colors plus window profile films heat up less than other window profile films. They are several degrees cooler under comparable outdoor conditions and color compositions – and so they last much longer.

[Translate to English:] skai cool colors

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