Cadillac's upcoming Celestiq flagship EV has a tint-shifting smart roof

Flip from transparent to opaque with the touch of a button.

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Andrew Tarantola
January 22nd, 2021
In this article: EV, Celestiq, Roof, SPD, GM, automotive, Cadillac, feature, gear
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GM has high hopes for its upcoming Cadillac Celestiq sedan, slated for release in 2023. The flagship EV is being built to help the brand recapture its reign as “the Standard of the World.” As such, it’s expected to arrive packed to the gills with cutting edge, futuristic technology including an all-glass roof that can adjust its opacity anywhere between crystal clear and completely opaque with the mere flick of a switch.

These roofs, dubbed SPD-Smartglass, have been designed and manufactured by Research Frontiers of Woodbury, New York and are based on Suspended Particle Device technology that was originally created as a replacement for the manual sliding window shades aboard commercial aircraft, Research Frontiers CEO Joe Harary told Engadget. Some of the earliest examples of SPD window treatments can be seen on the 2011 Mercedes Benz SLK roadster and in the 2012 Mercedes S Class coupe, which were used to increase headspace while eliminating the physical window shade screens, as well as various Mclaren models over the past decade. As the Youtube video below explains, Research Frontiers SPD tech relies on polyiodide nanoparticles to generate its tint effect.

“SPD technology is smart glass that allows you to change the tint of the glass,” Harary explained. “There's this film that we invented that has little nanoparticles in it, which you can control with a small electrical voltage. So, basically this film... that allows you to dial in whatever tint level you'd like.” 

“The crystals are about three to five tenths of a micron in length and they act as induced dipoles so when you apply an electric field to conductive coatings in the film,” Harary continued, “ the particles will line up, and allow light to pass through. Then, when you remove the voltage, their natural tendency is to be in the dark state due to Brownian movement and that causes the glass to tint.” 

As the tint partially blocks incoming photons, it also reduces the amount of glare experienced by the driver and the heat trapped within the vehicle -- over 99.5 percent of light and 95 percent of heat, per a January press release from the company. The claim is, this allows vehicle occupants to stay comfortable for longer without having to turn on the A/C, as well as keep the interior up to 18 degrees (F) cooler overall, Harary asserted.

“You're making the car safer because you're lowering the center of gravity and reducing the weight in the roof; you're using your air conditioning less” Harary said, adding that “Continental Automotive calculated that you can save four grams per kilometer of CO2 emissions,” by utilizing this tech. In places like the European Union, where drivers are taxed based on the amount of CO2 their vehicles emit per distance driven, cutting four grams per kilometer can translate into some significant operating expenditure savings -- around €380 (~$410) annually on average. 

What’s more, these weight and energy savings should translate into longer driving ranges for EVs since the battery’s stores aren’t being used to drive the A/C or help haul unnecessary added weight. Safety and acoustic dampening effects are increased as well -- at least compared to a conventional convertible top -- since you’re riding underneath a sheet of laminated glass rather than an aluminum roof frame and heavy canvas cloth.

We will, of course, see this technology in the Celestiq once it arrives in dealer showrooms in 2023. However, the Celestiq -- operating under the auspices of being Caddy’s new flagship EV -- is expected to be a hand-crafted monster of a sedan retailing for $200,000 and up, not exactly what most folks would consider affordable, especially in this economy. However, Harary remains confident that as the technology spreads, consumers will soon begin seeing it not just on more affordable car models but in billboards, advertising campaigns and even modern architecture.

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