The Autonomist
four passengers in a sketch of the interior of an autonomous car

               How to light an autonomous car

We need to rethink how we design lighting for the autonomous age. Here’s The Autonomist’s 10 golden rules for the interior illumination of driverless vehicles.

While software engineers have made enormous progress in teaching cars how to interpret the world around them and navigate it safely, less advancement has been made with the user experience that driverless vehicles will provide to passengers.

In fact, we haven’t even nailed the basics. Will be required to wear seat belts? Will the front seats face forwards or backwards or both? Can we stand up?

Will there be steering wheels? Centre consoles? Flat beds for sleeping? Tray tables? Desks? Wraparound screens? Vending machines in shared vehicles? All of the above?

Auto makers are already suggesting that the tech will be deployed sooner than everyone thinks. And while the bullish Tesla CEO Elon Musk is probably an outlier with his prediction that Level 5 autonomy will be with us by the end of next year, it’s clear that we all need to start thinking about a driverless future.

The creative industries, especially, should relish the challenge of reinterpreting a space where not much has changed for a century. Already some designers are imagining an immersive environment of virtual gaming, entertainment and learning experiences, gesture control and windscreens and windows which turn into visual displays at nighttime.

The designers of car interiors will soon be tasked with coming up with a lighting concept which matches this exciting vision (no pressure, guys).

But happily, the fundamentals of lighting don’t change, whatever the interior. So, we’ve compiled 10 golden rules to help them deliver illumination that will work seamlessly in the interior of an autonomous car.

a man asleep in a car beside a red light

Light for the passengers who’ll use the space and their activities.

Sounds obvious, but you’d be amazed at how often this rule is ignored in commercial and architectural buildings. What will people do in autonomous cars? It’s likely their activities will break down into four major types: working, relaxing, entertainment and sleeping, with a different arrangement of seating and screens for each. So working, for instance, will require task lighting for tables and reading, relaxation and socialising will require soft, low glare lighting, etcetera.

interior of a Chrysler Voyager people carrier

Layer the light: ambient, then accent and task

There are three lighting elements in any space: ‘ambient’ for general lighting, ‘accent’ to emphasise key elements and ‘task’ to help occupants read or work.

Traditionally car interiors have had just accent and task lighting but with these spaces effectively becoming living rooms, ambient lighting will start to make an appearance. Organic LEDs (OLEDs), which are low power, flexible and slim, are perfect for ambient and can turn the interior of the roof into a glowing sky.

two women chatting in a driverless car

Focus on faces

For the first time in car travel, we’ll be looking directly at other passengers’ faces. So it’s important to get it right. The best approach is to light faces from the sides, rather than from above. Think of Hollywood make-up mirrors with the lights on either side. Columns are the perfect location for this lighting, but make sure the light fittings give a soft light that’s flattering to skin tones. The colour rendering index (CRI) of the lights should be at least 80 and preferable over 90.

a luxurious car interior

Don't use downlights

For reasons best known to auto makers, miniature downlights have started to creep into car interiors. Often they’re billed as ‘map reading lights’. Well derr, in the autonomous world, we don’t read maps anymore so let’s ditch the downlights. Because the ceiling height isn’t comparable to, say, an apartment, all downlights do is put puddles of light on the floor. And they’re terrible on people’s faces, highlighting the top of the head while casting heavy shadows on the eyes. Ugh!

Interior of a driverless bus with lights

Compromise on colour temperature

Colour temperature is a measure of how ‘warm’ light appears. Incandescent light bulbs are a toasty 2700 Kelvin, while fluorescent tubes are a coolish 4000 or 5000 Kelvin. The problem with a global product such as a car is that preferences are cultural. Generally speaking, Northern Europeans and Americans like it warm while Asians, especially Japanese, like it cool. One, increasingly affordable, option is white colour tuning, which allows passengers to set their own colour temperature.

Blue light bathes a car interior

Use LOTS of lights

As a general rule, spaces look better – and more upmarket – with more low-output lights rather than fewer higher-powered ones. This is, after all, how you tell a posh restaurant from a cheap diner. The same with cars; lots of discreetly concealed and integrated light sources exude luxury. Happily, the lighting industry can help. Over the past few years, it has developed a plethora of top notch micro LED offerings including tiny marker lights and high-quality LED tape.

Two women in a dark car interior

Don't be afraid of the dark

Don’t be afraid of darkness…at least pools of relative darkness. Not everything needs to be illuminated. For instance, footwells don’t need light but every glove box, compartment and drinks store needs light to appear as soon as they’re opened. Think too, about how surfaces will reflect and interact with the light. Matt black carpets and seating fabric will suck in light, while high gloss surfaces may give unwelcome reflective glare to passengers.

a finger on a lighting control panel

Limit the choice of scenes

It’s tempting to give passengers lots of lighting options - because you can. But resist the temptation. Better to limit the choice of scenes and label them simply such as ‘sleeping’, ‘relaxing’, ‘working’ and ‘movies’ etc. Better still, build levels of intuition into the lighting system. At a basic level, lighting scenes should change when consoles, tables or seating is adjusted. Sensors could detect how passengers are interacting with the space, and adjust the lighting appropriately.

A car skylight with white clouds in a blue sky

Make it natural

There’s a lot of excitement about ‘human-centric’ lighting in the design profession at the moment. This is where the intensity and composition of the light changes dynamically to match our natural daily rhythms. In car interiors, we’re probably not getting enough daylight to stay engaged with our normal cycles, so the light could help. For instance, a bright blue light in the morning could make us feel awake and alert while a dim warm light – with no blue – would get us ready for sleep.

a car passenger playing a video game

Make the lighting part of the show

Technology is making it easier than ever to integrate the car’s interior lighting into the entertainment system. At a simple level, for instance, the colour of the interior could respond to the dominant hue of the movie scene being displayed on the screen. If you’ve ever seen a Philips Ambilight TV in action, you’ll know how immersive this is. Other technologies, such as amBX,allow sound and video to be mapped onto a three-dimensional space, allowing light effects to ‘move’ around.

© The Autonomist 2019 All rights reserved. Picture credits: Main pic: Courtesy Volvo; Pic 1: Philips Lighting Pic 2: LG Displays Pic 3: Courtesy Volvo Pic 4, 5 and 6: Shutterstock Pic 7: Courtesy Volvo Pic 8: Shutterstock Pic 9: Harman Interior Pic 10: Shutterstock.

By Martin Tomlinson
Design Editor, The Autonomous 

22 July 2019