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Look At This Before You Look At Your Solar Window Film Sample

Samples of solar window film are dangerous. Maybe not physically dangerous, but they do steer you to sub-optimal decisions. This is not ideal if you are investing your hard earned savings into making your favourite space more comfortable. Let's use the example of a conservatory solar window film sample.

The Solar Window Film Datasheet and Sample

The datasheet says that the conservatory roof solar window film sample has a visible light transmission of just 10 percent. The sample looks incredibly dark even when held to the light so it is understandable that you might be worried.

The Sun and Solar Window Film

However, today at twenty past one on the 26th of June 2020 it is 24 degrees Celsius in the shade and 30 degrees Celsius in the sun. The light measured is a whopping 120,000 Lux. To draw a comparison, the working environment is supposed to be 500 Lux for an office worker and 700 Lux for an engineer analyzing documents.

A significant amount of light needs to eliminate in order to tackle glare.

Examples of light levels
Very Bright Summer Day 100,000 Lux
Full Daylight 10,000 Lux
Overcast Summer Day 1,000 Lux
Very Dark Day 100 Lux
Twilight 10 Lux
Full Moon < 1 Lux

Visible Light and Perceived Light

Perceived light is what you see. Visible Light Transmitted is what is measured. The two are very different. Why are they different?

It Is Because You Are Amazing!

Your eyes and brain are incredible, even better than a sophisticated camera lens.

Image, top left - Eye with big pupil, top right - Eye with small pupil. Bottom left camera with a fully open lens, Bottom right - camera with semi-shut lens

It would be logical to assume that the room appears 50 percent darker when light levels are reduced by 50 percent. However, because of the way our pupils operate, the brightness does not follow measured light linearly. Instead, brightness follows a logarithmic curve.

If the measured light is 18 percent, then the perceived light level is 55 percent. If the measured light is 33 percent then the perceived light is approximately 68 percent.

Visible Light Transmission with Film

Light Transmission Perceived by the Human Eye
100% 100%
80% 80%
60% 82%
33% 68%
18% 55%

(Table sourced from Solargard)


The solar window film will appear two to three times lighter on the window than it does as a sample. When the ambient light level is bright your pupils are less dilated. The film looks darker.

When your conservatory is filmed, not only will it be cooler, the solar window film appears lighter. This is because your pupils will be more dilated and perceive more natural light.

Trust the science. Our objective is to give you the facts so that you can make the right decision for you.


Solar Window Film

Conservatory Window Film