Energy Crisis: Why We Benefit from Darker Cities | Knowledge & Environment | DW

Neuschwanstein Castle at night

Due to high energy prices, many cities have already refrained from illuminating landmarks, monuments and prominent buildings such as town halls, museums or libraries at night in recent weeks. In Berlin, the radiators have to be disconnected at around 200 objects. The Victory Column or the Berlin Cathedral are thus in the dark at night. Since September 1st, the Energy Saving Ordinance has officially banned the lighting of public buildings from the outside, neon signs may only be on for a few hours a day.

The city of Weimar turns the streetlights on 30 minutes later and off 30 minutes earlier in the morning. That’s why you don’t stand in the dark. The possible positive “side effects” of darker cities are manifold.

Neuschwanstein Castle at night

A magnet for tourists during the day, Neuschwanstein Castle sleeps again at night. The exterior lighting is switched off

Switching off the light in cities or on our own front door and only illuminating it where it is really needed not only saves electricity and money, but also has a direct effect on the climate and biodiversity.

Turning off the lights helps against air pollution

The NGO International Dark Sky Association estimates that every night about a third of all outdoor lights in the US burn to no avail. Even before the energy crisis and rising prices, this could save $3 billion a year. We have no figures for Germany. With fossil fuels still the main source of energy around the world, simply turning off unnecessary lights helps reduce air pollution and harmful emissions.

In India, for example, extreme lighting emits 12 million tons of CO2 a year, Pavan Kumar from the Rhani Lakshmi Bai Central Agricultural University in India told DW. That’s about half as much as the country’s total air and sea traffic per year. Better light management could significantly reduce the proportion.

In Singapore at night

In Singapore, the nights are almost daylight

Today more than 80 percent of people live under light-polluted skies, in Europe and the USA it is even 99 percent. For the people there, real darkness practically no longer exists. In Singapore, it is even so bright for the entire population that the eyes in public spaces no longer adjust to real darkness at all.

But there have long been ways to reduce light pollution and still not sit in the dark. Where light is not needed, it can be switched off. This applies to apartments, but also to streets, parks and public spaces. Motion detectors could be useful here. Lampshades direct the light to the places where it is really needed and prevent disturbing stray light.

Why we need darkness

Sufficient darkness at night is also good for your health. Studies show that eye diseases, insomnia, obesity and probably even depression are related to artificial light. This includes exposure to screens and white LED light indoors before bed. They can disturb the sleep rhythm.

One hormone in particular is of central importance: melatonin. “If we don’t produce this hormone because we are exposed to so much light in our apartment or as shift workers, then our biological clock system gets a problem,” says Christopher Kyba.

Satellite image of Europe at night

In Europe, the Milky Way has disappeared for almost 60 percent and in North America for about 80 percent of people

Another study suggests that children and teens who live in areas with lots of artificial light get less sleep and are more likely to suffer from emotional problems.

Artificial light at night is “one of the most dramatic interventions we have made in the biosphere so far,” says Dr. Christopher Kyba Geoinformatician at the GeoForschungs Zentrum Potsdam to DW. Throughout evolution, “there was this constant signal coming from the environment. This is day, this is night, this is the phase of the moon. In areas with heavy light pollution, this signal changed,” Kyba continues.

Dimming the street lighting or partially switching it off could also be a first step to counteract this in the future, even if the new regulations should no longer apply. How light or dark a place is has no bearing on accident or crime rates, according to a 2015 study in England and Wales.

Animals and plants also like it dark

Insects in floodlights

Many insects cannot help but fly towards light sources. The fatal attraction of light is often their downfall

But animals also need a dark night. Birds, which previously could easily lose their orientation over bright city skies, would have a better chance of keeping their perspective over darker cities.

This is especially true for insects. Switched off lamps could save entire insect populations in summer. As everyone knows, light has a tremendous attraction for all nocturnal insects, from mosquitoes to flies and moths. In Germany alone, an estimated 100 billion individuals die every summer due to the attraction of artificial light to insects. A bright street lamp replaces the moon, which the animals normally use to orient themselves. The result: insects can’t help but fly around the lantern non-stop. The next day they are so exhausted that they can no longer reproduce, die or are easy prey for predators.

England Tetbury |  Illuminated Trees

Even trees like it dark

This also has consequences for the pollination of plants. A study published in 2017 showed that plants that grow near streetlights are pollinated significantly less frequently at night and bear fewer fruits than their unlit counterparts. Trees also feel the influence of light at night. They will sprout earlier if they are near streetlights.


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