idw – Informationsdienst Wissenschaft
Nachrichten, Termine, Experten
Nachrichten, Termine, Experten
An idea which originated at the Fraunhofer Institute for Solar Energy Systems ISE will shortly go into pilot production at the Interpane company: Insulating glazing units, which darken at the press of a button. Instead of conventional, mechanical roller blinds, the solar control and glare protection of the future will be based on a maintenance-free, electrochemical process, which changes the window transmittance continuously. The product will also be available through professional wholesalers within the near future.
When the pilot production plant for gaschromic panes has been set up in autumn 2001 at Interpane in Lauenförde, Germany, the project leader at Fraunhofer ISE, Wolfgang Graf, will have good reason to celebrate: "We have developed this technology to the pilot production stage in the record period of around 1 œ years. That was possible only because we had everything we needed under one roof at the Institute: fundamental research, systems technology, marketing, and direct contact to architects as future users".
The glazing units from the pilot production are intended for demonstration projects in large-area facades. In addition to detailed technical issues, the researchers are particularly interested in the reactions of the users.
What are the advantages offered by glazing which darkens at the press of a button? When not much sunshine is evident, what light there is will be received with open arms and can contribute to lighting and heating in a building. In summer, when the risk of overheating threatens, particularly in office buildings, the window can be darkened by pressing a button to the point that sufficient light is still available, but excess heat does not enter the room. In this way, solar energy and daylight can be used optimally, and often air-conditioning is no longer required.
Another benefit: Architects have more freedom in designing the building envelope and do not have to be so concerned about excess solar gains. They can dispense with complicated sun-shading elements, which mark the appearance and require intensive maintenance.
Many types of application are possible: windows, facades, spandrel elements, glazing for vehicles. As an example: a modern bus prototype allows the passengers to have an unhindered view through the side windows while they remain comfortably cool.
Interior glazing is a completely different application case. Switchable privacy walls in an open-plan office can screen confidential discussions if desired, or they can encourage communication in the fully transparent state.
The technical background to the "gaschromic" glazing was a particularly bright idea: Hydrogen is the element responsible for the transmittance, which can be varied continuously between 1 and 75 %. The inner surface of the insulating glazing units is coated with tungsten oxide (WO3). This invisible film takes on a deep blue colour when it comes into contact with smallest amounts of hydrogen. The colour is bleached away if oxygen is introduced.
How does hydrogen enter the window? Very simply: Concealed in the spandrel zone of the window, a small electrolyser and a pump provide the required gas mixture in a closed system. After installation, the windows will be free of maintenance for the next 20 years or more. "The user does not notice the technology at all", explained Graf and added, "The hydrogen concentration is so low that even if the windows should break, it does not present any danger."
The visual impression during switching is fascinating: Just as with a solar eclipse, the light level changes evenly and silently within a few minutes. Thus, each office can be adapted individually to the weather in accordance with the occupants' preferences.
Information material:
Fraunhofer ISE, Press and Public Relations
Tel. +49 (0) 7 61/45 88 -1 50, Fax. +49 (0) 7 61/45 88-3 42
e-mail: info@ise.fhg.de
You can also obtain pictures of the gaschromic windows at this address.
Contact person for further information
Project Leader:
Wolfgang Graf, Fraunhofer ISE
Tel. +49 (0) 7 61/4 01 66 -85, Fax +49 (0) 7 61/4 01 66 -81
Gaschromic windows
None
Criteria of this press release:
Construction / architecture
transregional, national
Research results
German
Gaschromic windows
None
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