A trend topic at this year's Light & Building 2024 was the use of amber and red LEDs in outdoor lighting to protect insects and other nocturnal animals. In terms of preserving insect populations, it has been shown that a warm white spectrum with reduced levels of ultraviolet (UV) and blue wavelengths is crucial for insect protection. It has long been known that UV radiation and blue light exert a strong attraction on many insect species. The use of white LEDs in outdoor lighting with the typical peak at 450 nm – 460 nm is particularly critical in this regard. Amber or red LEDs can significantly reduce insect attraction and thus contribute to biodiversity conservation. For this reason, various manufacturers have developed outdoor luminaires that change the colour temperature from warm white towards amber or red and reduce the luminous flux from a certain time onwards.

The spectrum of artificial lighting also plays a role in lighting coastal areas where sea turtles seek their places for laying eggs at night. White light, often used for coastal lighting, can affect the natural orientation of sea turtles, which visit coastal areas for nesting, as it distracts them from natural light sources such as moonlight or the reflection of the moon on the sea surface. Hatchlings that have just emerged from their eggs are also often attracted to artificial light sources instead of following the natural reflection of the moon on the sea surface. This often leads them to move in the wrong direction and become endangered on land. Therefore, it is crucial to use light with a long-wavelength spectrum that has low levels of blue light to minimize the disturbance of the navigation patterns of these animals.

The attraction of insects and sea turtles to white light can be attributed to the structural and spectral similarity of this lighting to natural light sources such as moonlight, which these species use for navigation. However, by specifically adjusting the spectrum, the negative effects of lighting on these sensitive ecosystems can be significantly reduced.

What is your experience with the use of amber or red light in outdoor lighting?

Is there a law or regulation stating that amber or red light must be used at night in your country?

How would you illuminate areas that don't necessarily need to be illuminated for safety reasons? Would you illuminate your garden with red light to protect insects, or would you prefer to switch off the light or dim it significantly?