The role of modern industrial lighting concepts in a sustainable future

The impending environmental apocalypse is really killing our buzz: If current trends continue, nature conservation organisations and scientists say that the insect population will be absolutely decimated. In Germany alone, around three quarters of all flying insects have vanished over the past three decades; insect numbers continue to decline by 0.93% annually. Without effective measures to combat dwindling insect numbers, scientists warn that they could face total extinction within a century. This would have dire consequences for both biodiversity and human sustenance, since 85% of all plant species need insects, with around a third of all foodstuffs in the Western Hemisphere relying on insects for pollination.

The causes of insect mortality are myriad – major factors include soil sealing, intensive farming coupled with the increasing prevalence of monoculture production, overfertilisation, and the use of pesticides. Another culprit is light pollution, given that half of all insect species are nocturnal. The cover of darkness affords them a measure of protection from predators; over millions of years, they have learnt to navigate by the light of the moon and the stars, enabling both feeding and breeding at night. Artificial lighting, however, disrupts the animals' long-established rhythm.

The night sky is now so aglow with light from towns and industrial facilities that it is also significantly hindering humans' ability to observe the stars above us. The area of the Earth's surface that is illuminated is currently growing by around 10% a year, while the amount of artificial light being emitted from the ground is increasing by around 2% annually. This poses a problem: Artificial light attracts insects, and it also attracts their predators. Up to 40% of insects attracted by streetlights perish – they become another creature's meal, die from dehydration, or succumb to the excessive heat produced by the lamp. Artificial light endangers other animals too, a notable example being newly hatched sea turtles – confused by the lighting emitted by nearby industrial facilities, they can fail to find their way into the water.

Politicians recently turned their attention to the problem, resulting in new regulations governing installations: In June 2021, Germany voted through a bill aimed at preserving insect diversity, which included measures to counteract the harmful effects of lighting. Most of the changes, which were incorporated into the German Federal Nature Conservation Act (BNatSchG) with the adoption of this insect conservation act, have been in force since March 2022. This legislation provides the basis for enacting ordinances aimed at reducing light pollution, for example. Although "light pollution" is not currently a legally defined concept, this legislation requires that the German Federal Ministry for the Environment, Nature Conservation and Nuclear Safety take certain measures in this area, e.g. imposing light emission limits and specifying technical and design requirements for lighting in the interest of animal conservation.

Some countries have made greater headway in this regard, albeit not necessarily with the same motivation – preserving the ability to make astronomical observations and saving energy are among the factors that have spurred their efforts. Public awareness of the animal conservation aspect has been slow to take hold, and it has taken far too long to appear on international legislators' radars. Meanwhile, it has been on the International Dark-Sky Association's agenda since 1988. Founded by astronomers, the International Dark-Sky Association is a movement that considers the natural night sky to be part of our world heritage, which therefore ought to be protected. Light that is emitted towards the sky poses a particular problem, as it scatters in the layers of the Earth's atmosphere and inhibits the natural darkness.

Modern lighting technologies like LEDs are not only part of the problem – they are also the key to solving it. An unfortunate side effect of LED lighting being so energy efficient is that we are now illuminating a greater surface area than ever before. Yet its potential to be a pivotal part of the solution comes into focus when we consider the differences in the way humans and animals perceive light: Blue light and UV radiation (wavelength < 450 nm) appear brighter to animals (especially insects) than to humans, whose eyes perceive light at wavelengths of 555 nm and above as very bright. Many nocturnal insects are excellent at detecting UV radiation, which lies outside of the spectrum normally visible to humans.

The blue light and UV radiation emitted by the fluorescent lamps and mercury vapour lamps currently used in industrial facilities and outdoor lighting installations make them a poor choice for insect conservation, as insects perish on contact with the lamps' incredibly hot surfaces. LED lamps, on the other hand, emit no UV radiation, and the blue light content can be selected to suit requirements. The greater the blue light content, the whiter and colder the light colour. Light fittings that use warm white LED light sources attract very few insects. So it comes as good news that the EU authorities have decided to consign fluorescent lamps to history. In accordance with Commission Regulation (EU) 2019/2020 ("Ecodesign requirements for light sources"), the most common fluorescent lamp sizes – T8 and T5 – may no longer be placed on the market.