Smart windows with electrochromic film—almost ready for prime time

December 4, 2015
Smart windows with electrochromic film—almost ready for prime time

EC film devices have been hampered in making the move from research to innovation by a number of technical and economic obstacles. EELICON aims to overcome these obstacles by removing equipment limitations, automating processes, and validating a possible high-throughput prototype production process for a cost-effective, high-performance EC film technology.

Retrofitting windows with an electrically dimmable plastic film is a dream that is finally coming close to fruition. According to studies, considerable energy savings may result when such films are included in architectural glazing, appliance doors, aircraft cabin windows, and vehicle sunroofs; and user comfort is enhanced as well.

The EU-funded EELICON (Enhanced Energy Efficiency and Comfort by Smart Light Transmittance Control) project is focusing on an innovative switchable light transmittance technology that was developed in a project previously co-funded by the EU Framework Programmes. The project developed mechanically flexible and light-weight electrochromic (EC) film devices based on a conductive polymer nanocomposite technology with a property profile far beyond the current state-of-the art.

Dr. Uwe Posset, project coordinator and Expert Group Manager at ZfAE - Center for Applied Electrochemistry, Fraunhofer ISC, discusses the project's achievements so far.

Do you have any results to show regarding the objectives that you have defined?

We are indeed working on a demonstration line to roll out a possible production process for electrochromic (EC) films, i.e. plastic films that can change colour upon application of a small voltage. Such can be used to create smart windows for the control of sunlight and glare in buildings and vehicles. This technology is known to have the potential to save substantial amounts of energy for air conditioning. Darkening the film will decrease heat gain in the interior while maintaining the view through the window. The film provides possibilities to retrofit existing windows.

Do you have results from a life cycle assessment (LCA)?

Yes. The results essentially show that the targeted film technology can be produced with less primary energy than a standard EC window. We are currently working on extending the LCA to demonstrate the energy saving potential of the EC film during the use phase.

How much do you expect the technology to cost? How competitive will it be with existing technologies (e.g. price/performance)?

We target a price level of 200 €/m2, which is about a factor of 4 less than standard EC windows based on glass. To be really competitive, an even lower price may be required, but 200 €/m2 is usually discussed in the community as a threshold price for competitiveness. A full performance evaluation is currently in progress. According to discussions with potential end-users, producers and customers, price is the major driver, while some performance aspects may be negotiable, depending on the application.

How easy or difficult will the technology be to commercialise?

It is a complex process presumably requiring an industrial development phase of 2-3 years after the end of the project and substantial investment (currently estimated: €10 million).

Which are the most promising application areas?

Smart windows for energy-efficient buildings, vehicle sunroofs, smart aircraft cabin windows, switchable appliance doors, smart eyewear and visors.

What are the main benefits provided by the technology (any quantitative data would be welcome in addition to a qualitative description)?

There are many benefits. What we are developing is a film-based technology suitable for window integration and retrofitting. It will have short switching times (<1 min as compared to 10-15 min for state-of-the-art EC windows), and most importantly cost-effective, high-throughput production will be possible (roll-to-roll manufacturing).

Our will also have a higher bleached state visual light transmittance as compared to state-of-the-art EC windows (60-65 % vs. 50-55 %); a lower darkened state visual light transmittance as compared to state-of-the-art EC windows (5-10 % vs. 10-15 %); it will be fully colourless ("neutral tint") bleached state with no residual colour or hue.; it will have an appreciable g-value modulation as opposed to liquid crystal-based smart window film technologies; it is mechanically rugged; and it has a large thermal operation range (-25 to +60 °C).

Once the project is completed, what will be the next steps? How do you see the technology evolving in the future?

We will then have to focus on industrial development – scaling from pilot to production scale. Huge markets will become accessible in the future if the price target can be met and minimum performance requirements are fulfilled.

Explore further: Wrapping buildings in a layer of insulating liquid

Related Stories

Anti-aging treatment for smart windows

October 1, 2015

Electrochromic windows, so-called 'smart windows', share a well-known problem with rechargeable batteries – their limited lifespan. Researchers at Uppsala University have now worked out an entirely new way to rejuvenate ...

Researchers develop cheaper 'smart windows'

February 3, 2015

Researchers from the Spanish National Research Council (CSIC) have developed a novel technique that reduces the costs of the 'smart windows', with which the amount of light passing through glass can be controlled. This technology ...

Smarter window materials can control light and energy

July 22, 2015

Researchers in the Cockrell School of Engineering at The University of Texas at Austin are one step closer to delivering smart windows with a new level of energy efficiency, engineering materials that allow windows to reveal ...

3M shows photovoltaic film for windows

October 7, 2011

( -- 3M drew press and viewer interest earlier this week at CEATEC with its show of special film that the company has developed to coat ordinary, existing windows and convert them into solar panels. The product ...

Shedding a scientific light on e-commerce management

August 25, 2015

e-Commerce (EC) sales have been increasing consistently for decades all over the world. Although EC has great advantages over traditional commerce, succeeding in EC business is not an easy task.

Recommended for you

Microsoft aims at Apple with high-end PCs, 3D software

October 26, 2016

Microsoft launched a new consumer offensive Wednesday, unveiling a high-end computer that challenges the Apple iMac along with an updated Windows operating system that showcases three-dimensional content and "mixed reality."

Making it easier to collaborate on code

October 26, 2016

Git is an open-source system with a polarizing reputation among programmers. It's a powerful tool to help developers track changes to code, but many view it as prohibitively difficult to use.

Dutch unveil giant vacuum to clean outside air

October 25, 2016

Dutch inventors Tuesday unveiled what they called the world's first giant outside air vacuum cleaner—a large purifying system intended to filter out toxic tiny particles from the atmosphere surrounding the machine.

1 comment

Adjust slider to filter visible comments by rank

Display comments: newest first

John Edwards
not rated yet Dec 11, 2015
It will be interesting to see where this is going. Personally I think thermochromic glass like for example Suntuitive produces may be what we will see more of in the future because of its ease of implementation (since no electricity is needed). Retrofitting doors, windows etc to wire the film may come with its complications.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.