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Smart glass means smart windows

We have seen huge improvements and developments with window design and manufacturing techniques, and what started as a hole in the wall to let in light has become the standard in every building today. A window continues to serve its original purpose, but with the revolutionary steps being taken in glass production, are we on the cusp of space age windows?

Competing window technologies

Just when your thought triple glazing and solar control glass were the new boys in town, along come smart windows to break through the barrier and take the crown with ease. Although the main 3 have differing technologies and functions they all come under the smart window umbrella. These 3 types are:

  • Electrochromic or Suspended particle device (SPD)
  • Liquid crystal
  • Thermochromic

Electrochromic and SPD (suspended particle device)

How many times do we have to close our curtains or pull the blinds because the sun is too bright? With both of these technologies it’s possible to flip a switch and alter the window glass to any level of tint you require. The function is controlled by a very low voltage and is just as instantaneously reversed as it is actioned. The research being done shows that controlling the intensity of sunlight into solar glass can actually have a positive effect on maintaining those all important solar heat levels.

One producer of Electrochromic glass has found that installed in Commercial premises it “improves productivity and job satisfaction by enhancing comfort and helps your bottom line by cutting energy costs”.

Liquid Crystal

These commercially available windows are used to control privacy, much in the way frosted glass does in bathroom and front door windows. The majority of us will recognise the liquid crystal function being used in calculator, smartphone and laptop displays but have no idea how it actually works.

In its normal ‘off’ state, the liquid crystals are randomly distributed within the (in this case) glass, so preventing light from penetrating through. On the application of an electric current, the crystals align into a uniformed shape allowing light through and turning the glass clear. The downside of this glass is that it requires a constant supply of energy to perpetuate translucency and therefore provides no energy savings.

Thermochromic windows

The word therm is a bit of a giveaway and quite rightly suggests that its heat from the sun that causes thermochromic glass to become tinted. The patented thermochromic filter technology automatically tints the window glass when sunlight reaches its brightest and then recedes when the sun sets.

These windows work optimally in all seasons, by darkening in the heat of the summer, therefore reducing the solar heat gain and in winter, generating the maximum amount of light –  thus keeping the heat in. The downside to these windows is the loss of transparency when tinted, hence thermochromic windows are suited for out of sight windows such as skylights.

Here’s an interesting story. Although Edwin Land, inventor of the Polaroid camera, is regarded as the inventor of SPDs, there is a story that its actual discovery is credited to a British Chemist and his dog. Late 1800’s the chemist gave his dog some quinine bisulfate to settle its upset stomach and when the dog accidentally urinated on some iodine, the chemist noticed the formation of green crystals that could filter light. These green crystals were later used by Land to make a pair of glasses that could suppress light.

Finally, with all of these wonderful new inventions I guess the big question is, will  we really need curtains and blinds?