How The Boeing 787 Dreamliner’s Dimmable Windows Work

The Boeing 787 is an innovative and groundbreaking aircraft in so many ways. From its mix of composite materials, fuel-efficiency, and comfortable cabin pressure to its large, electrochroamatic windows. But how exactly does the technology behind that dimmer switch actually work?

Boeing 787 windows
How do the 787 windows dim? Photo: Getty Images

The Boeing 787 Dreamliner has the largest windows of any passenger jet. They measure a full 10.7 by 18.4 inches in size. That is in comparison to the second-largest belonging to the 777 at 10 by 15 inches.

But, of course, the Dreamliner’s windows are famous not only for their size, which makes the window seat, if possible, an even more coveted commodity, but also for the lack of mechanical blinds.

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Electronically dimmable windows

Instead, the 787 features electronically dimmable windows (EDW). Buttons beneath the windows allow passengers (well, two per row in any case) to regulate the amount of light entering the cabin. But how does the gradual lightening or darkening of the window work?

Boeing 787 Dreamliner
The 787 has the largest windows of any commercial aircraft to date. Photo: Getty Images

Electrical current through gel

The windows are not made up of one single pane of glass. Of course, all aircraft windows have several layers of glass or stretched acrylic material to withstand the pressure differential inside and outside the plane.

However, the panes of the Dreamliner’s windows, manufactured by a company called Gentex, have a layer of gel in between them. When an electrical current is applied to the gel, it causes a chemical reaction that alters its opacity. The higher the voltage, the darker the gel becomes. And, vice versa, less current leaves the gel lighter, and none at all lets it return to a clear state.

In this way, these electrochroamatic windows can go from transparent to black-out-curtain with the press of a button.

Networked for master switches

The electrodes are placed to the sides of the windows, behind the inner panels, and out of view for the passengers. Meanwhile, they are all networked together so that the cabin crew maintains control through master switches.

This comes in handy when traveling through time zones to allow travelers some more shut-eye. And furthermore, it enables the crew to settle any off-chance “blind up or down” dispute.

When they were first introduced, the windows could not go entirely dark, and criticism was raised that they let in too much light in the harsh sunlit conditions above the clouds. However, the manufacturer made improvements to the technology in 2015. Now, they can block out almost all light, similar to traditional blinds. Furthermore, the transition time from clear to dark has been halved.

Boeing 787 windows
After improvements, the windows can block out nearly all light. Photo: Getty Images

These windows are supposedly maintenance-free and should last for as long as the plane, or 20 years at the very least, according to Boeing. But no, they are still not allowed to be dimmed during take-off and landing.

What is your experience with the Dreamliner’s windows? Let us know your thoughts in the comments.