How Do Those Dimming Dreamliner Windows Work?

If you've flown on a Boeing 787 Dreamliner aircraft, you know the windows are a bit different. After looking for the window shade at the top of each huge window, you may have realized there isn't one. Instead, there are buttons that allow passengers to customize how much light they want to let in.

But without a solid shade to cover the window to block out the light, how does this work?

The windows are not made from one single piece of glass. Given what would happen to the pressurized cabin if the glass broke, you wouldn't want a single layer anyway. These Dreamliner windows have two pieces of glass with gel sandwiched in between them. This gel has an electric current running through it, which increases or decreases based on the dimming level selected by the passenger in the window seat. The higher the current, the darker the gel becomes and therefore, the less light that can be seen through it. Decrease the current and the gel lightens up just as your view outside does.

When the windows were first introduced, the gel initially turned a dark blue at their darkest setting/highest current, but they wouldn't go completely dark. However, window manufacturer Gentex has improved the technology of this design, allowing the gel to turn black, completely blocking out the light and providing darkness in the cabin the same or similar to traditional window shades.

While each passenger can fiddle around with the different settings, the cabin crew also have a master control where they can change the gel color of a single window, a section of windows or the entire aircraft. This is handy if the crew wish to keep the sunrise out for as long as possible to help passengers maximize their sleep when flying through multiple time zones on a relatively short red-eye flight. However, the downside of this is that it takes away control from each passenger as to how they want their window set.

Next time you're flying on a Dreamliner, take a look out the windows, which are 65% larger than traditional aircraft windows, and play around with the dimmers. Boeing says that these windows (and the gel inside them) will last at least 20 years, and the manufacturer plans to work with Gentex and other companies to make similar advances in the passenger experience.