Light Matters: Recovering The Dark Sky

The advent of electrical lighting has allowed us to colonise the night. Not only have kilometres of street lighting ensured higher levels of safety, but signs, advertisements, etc. continue to draw us into nocturnal landscapes. As Rem Koolhaas explored in Delirious New York, Manhattan and Coney Island were the early luminous prototypes for today’s continuously vibrant metropolises: cities that establish new rhythms, a new balance between work and life. 

But what happens when lighting upsets our natural balance? When we lose the beauty of the dark sky, the stars? What happens when lighting turns into pollution? 

More Light Matters, after the break...

Irrespective of whether you live in an Asian megacity or a small village in the Alps, electrical lighting has replaced moonlight. Particles in the sky reflect urban light emissions and reduce the opportunity to enjoy the stars at night. Not only does this “sky glow” affect people, particularly astronomers, but also other organisms, such as birds that are orientated by stars.

Light trespass. The City Dark. Film by Ian Cheney. Press photo. Image Courtesy of

Due to the abundance of light, we have almost forgotten how sensitively our eyes can perceive the environment at night. Moonlight is sufficient for us to identify objects around us and find our way. Our eyes can handle extreme differences - sunlight at noon with up to 100.000lx and a moonlit walk with around 0,25lx - and so small changes do not make a difference: if you see a contrast of 50% you will hardly notice the variation. Your eyes start to perceive a brightness contrast from about 20%. 

The city of Vienna confirmed this phenomenon by reducing street lighting by 50% for one hour each night. As Thomas Posch from the University of Vienna’s institute for astrophysics  discovered, hardly anyone noticed - except for astronomers, who detected a significant reduction in light pollution. The city treasury, on the other hand, was all too aware of this phenomenon: they saved 200,000 Euro per year. 

In the U.S. alone, light pollution wastes energy amounting up to $2.2 billion per year, as stated by the Dark-Sky Association. Christian Luginbuhl, astronomer at the United States Naval Observatory, Flagstaff Station, and his team discovered that the light pollution of Flagstaff, Arizona derives firstly from commercial lighting (36%) and then from illuminated sports grounds (32%), traffic ways (12%) as well as from private households (9%). 

Satellite composite of the earth at night. Credit: Data courtesy Marc Imhoff of NASA GSFC and Christopher Elvidge of NOAA NGDC. Image Courtesy of Craig Mayhew and Robert Simmon, NASA GSFC

Posch points out that 100 years ago street lighting alongside roads had only an illuminance of 0,25 Lux, whereas today we have between 25 to 75 Lux on busy roads. Posch encourages a reduction of lighting by half or even three-quarters for low traffic periods. The city of Augsburg in Germany, for example, has adopted this strategy successfully. 

Critics of lower light levels often argue that the crime and accident rate would increase. However, surprisingly, studies show that dark areas do not relate with a higher frequency of incidents nor that more light would lead to higher traffic safety, explains Ursula Pauen-Höppner and Michael Höppner from a Berlin research group. 

Starry Night by Tunc Tezel. Valleys near Uludag mountain in Turkey. Image Courtesy of Tunc Tezel and TWAN

Many researchers and designers have come together to analyse the ecological effects of outdoor lighting and to raise public awareness. The Dark Sky Association, for example, was founded in 1988. Governments have established interdisciplinary research projects, such as the “Loss of the Night” project in Germany, that consider light pollution from technical, social, ecological, and health perspectives.

Metropolis 40°25' N 3°41' W (Madrid) from the series Lux by Christina Seely. Image Courtesy of

The “Earth Hour” project, a more symbolic occurrence, where all lights were switched off for one hour in Sydney in 2007, has transformed into a worldwide event, with 7001 cities in 153 countries partaking this year. Other initiatives include: “Night seeing” tours by lighting designers; books like The End of Night by Paul Bogard; photo competitions from TWAN; publications like “Lux” by photographer Christina Seely, “Helvetia's Dream“ by Alessandro Della Bella, ”Our Vanishing Night” by Jim Richardson or “Darkened Cities” by Thierry Cohan. The documentary, The City Dark, from 2011, revealed how the loss of darkness has turned into an essential sociocultural discussion, and that its return will require a substantial commitment.

An essential aspect for returning to the dark sky is the awareness  of light pollution, the realization that this is an increasing problem, and that society must take responsibility – starting with the light at your entrance door. Some communities and regions have already approved laws, which restrict lighting. Slovenia, which began regulating against light pollution in 2007, is an early initiator. However, the pollution of light will never truly be eradicated until each individual is both aware and committed to overcome it. 

As Susan Harder, founder of the Dark Sky Society, was quoted in an interview with the New York Times some time ago: ”One day we’ll look back at light pollution in the same way we do the recycling or ecology movements, and wonder how we ever could have thought otherwise.”

Precise lighting technology avoiding light pollution. Benrath Castle, Duesseldorf, Germany. Architect: Nicolas de Pigage (1723-1796). Lighting design: Architekturbüro Lamprecht, Vienna. Image Courtesy of ERCO, Thomas Mayer,

Beyond legislation, how can citizens begin to reverse the loss of the night? Here are five tips you should always keep in mind:

Illuminance - Familiarize yourself with the environment and evaluate how much light is really needed in the evening and at night. Minimize illuminated surfaces: for example,try illuminate detail rather than floodlighting a whole façade.

Direction -  When illuminating a façade, it’s best to do so from the top down rather than from the bottom up,in order to prevent light trespassing into the sky. 

Light source - Select a spectrum that does not harm insects or other animals, for example ultraviolet light.

Luminaires - Avoid fixtures with very wide lighting distribution; instead choose luminaires with clearly defined light beams, which you can easily direct to the designated target.

Control systems - Dimmable light sources allow you to finely adjust the illuminance to the necessary level. Time or motion sensors, which let you dim at certain hours or depending on traffic,allow for further optimization of energy consumption. 

Bollard luminaire with precise light guidance system with defined cut-off angle for dark sky. Image Courtesy of ERCO

Light matters, a monthly column on light and space, is written by Thomas Schielke. Based in Germany, he is fascinated by architectural lighting, works for the lighting company ERCO, has published numerous articles and co-authored the book „Light Perspectives“. For more information check or follow him @arcspaces

About this author
Cite: Thomas Schielke. "Light Matters: Recovering The Dark Sky" 23 Aug 2013. ArchDaily. Accessed . <> ISSN 0719-8884

You've started following your first account!

Did you know?

You'll now receive updates based on what you follow! Personalize your stream and start following your favorite authors, offices and users.