Self Tinting Windows

Hyderabad Aug 16, 2020

Self-Tinting or Smart Windows are wonders of modern technology that helped create climate-adaptive blankets around offices and homes. They are made from Electrochromic materials. Electrochromism refers to the ability of materials to switch colors when energy in a suitable form is applied across them. Glasses installed with such materials go from transparent to tinted when light transmission properties get altered by applying either sufficient electric voltage or light or heat.

Most conventional glass windows that are installed in buildings broadly have a three layer system - an outer glass pane, a layer of air, and an inner glass pane. This system is quite robust and can be useful throughout the year as it helps cool buildings when it is hot outside, and help warm the buildings during colder times.

Smart windows are exceptionally good when it comes to conservation of energy. They form an opaque layer when activated and help separate the surroundings from the inner atmosphere. The tint reflects light and heat from the surroundings, dynamically reducing the power consumption by air conditioners to cool the interiors of the buildings. Scientists estimate that this can bring down the average consumption of electricity by at least 20% of the current cost.

There are many such smart windows in the market but, their response time  (when suitable energy is given) varies a lot. Some of the existing smart windows take anywhere between 1-3 minutes to become fully opaque or fully transparent. Given how inconvenient it could get, developing something that can reduce the time taken for this, is of utmost importance.

Scientists Cheng and Berlinguette from the Berlinguette group at the University of British Columbia (UBC), have devised a novel method of making such windows. The main challenge these researchers wished to address was making electricity - responsive colour changing glass materials, for a faster response time. The method deposits a liquid solution containing a metal ion onto glass and uses ultraviolet light to transform it into a glass coating film. The transparent film becomes blue when electricity passes through, creating the active component of a smart window. This new method manufactures windows sans high temperatures and with high sophistication! It works on the simple principle of electron excitation. Once they receive sufficient energy, they remain in the excited stage until a reversing de-excitation of sufficient magnitude is supplied.

This helped address most of the issues like responsiveness, opacity of the tint, etc. One could make the glasses transparent/opaque at the flip of a switch! While all of these make their product quite attractive to the consumer, their cost of production is several times higher (for a square meter of ordinary glass that costs $60-$200, electrochrome glasses cost $500-$1000). Manufacturers however predict that 10-20 years down the line, they may get cheaper due to increased demand.

Tags

Alchemy - The Chemistry Association; BPHC

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