'Smart' window switches to dark mode to save energy

A building "Smart" windows could help save energy costs

Related Stories

A new type of "smart" window that switches from summer to winter mode has been made by South Korean scientists.

The window darkens when the outside air temperatures soar, and becomes transparent when it gets cold in order to capture free heat from the sun.

Similar windows already exist, but the researchers say their method allows for an almost instantaneous switch from opaque to transparent.

This may help save more energy, the team writes in the journal ACS Nano.

"This type of light control system may provide a new option for saving on heating, cooling and lighting costs through managing the light transmitted into the interior of a house," said the scientists.

"Smart windows can prevent the inside of a building from becoming overheated by reflecting away a large fraction of the incident sunlight in summer.

"Alternatively, they can help keep a room warm by absorbing the sun's heat in winter."

New approach

The existing technology uses charged particles called ions sandwiched between panes of glass.

Electric current is then applied to switch the window from opaque to clear and back.

Start Quote

[If] you're allowing light in much quicker, this can reduce the amount of heat loss out of houses or increase the cooling in summer”

End Quote Dr Steven Morris Technology Strategy Board

But Ho Sun Lim from Korea Electronics Technology Institute, Jeong Ho Cho and Jooyong Kim from Soongsil University decided on a different approach.

They used a special polymer, a different sort of charged particles known as counterions and solvents such as methanol.

The report states that the result was a glass that was a lot cheaper to manufacture and much less toxic than those currently available on the market.

The window is able to switch from 100% opaque to almost completely clear in a matter of seconds, said the authors.

'Instantaneous' switch

Although "dimming" windows already exist, it is often necessary to switch them from winter to summer mode and back manually, using additional equipment such as home-automation panels.

"Until now, the numerous technologies developed not only have been chemically unstable, prohibiting their use in long-term switching applications but have been accompanied by the use of expensive special equipment and complicated harsh processing conditions," stated the report.

Dr Stephen Morris from Materials Knowledge Transfer Network that is funded by the UK's Technology Strategy Board said that if the new method allows the window to switch from opaque to transparent and back pretty much instantaneously, then it is going to be a real benefit in terms of energy savings.

"That would mean that you're allowing light in much quicker - and this can reduce the amount of heat loss out of houses or increase the cooling in summer," he said.

More on This Story

Related Stories

More Technology stories



  • A very clever little girlBrain gain

    Why are people getting better at intelligence tests?

  • BeefaloBeefalo hunt

    The hybrid animal causing havoc in the Grand Canyon

  • A British Rail signBringing back BR

    Would it be realistic to renationalise the railways?

  • Banksy image of girl letting go of heart-shaped balloonFrom the heart

    Fergal Keane on the relationship between love and politics

  • Don Roberto Placa Quiet Don

    The world's worst interview - with one of the loneliest men on Earth

Try our new site and tell us what you think. Learn more
Take me there

Copyright © 2015 BBC. The BBC is not responsible for the content of external sites. Read more.

This page is best viewed in an up-to-date web browser with style sheets (CSS) enabled. While you will be able to view the content of this page in your current browser, you will not be able to get the full visual experience. Please consider upgrading your browser software or enabling style sheets (CSS) if you are able to do so.