(Dim) Light Ahead

My most remembered bus trip was in 2013 in Cambodia - a night ride from Phnom Penh (the capital) to Krong Siem Reap (the town near the famous Angkor Wat temple complex). The window views were absolutely unreal, as the darkness was impenetrable, with galaxies above our heads and hundreds of violet tubes on the horizon.

The tubes were used to attract insects which were then captured and used as a food source. Insects are now considered super food and have been very popular in Cambodia for years. And the popular harvesting method is based on blue/violet light attracting them in the night.

Insects' vulnerability to blue light has now become a serious problem. They were not affected by "warm" sodium street lights. But now sodium lights are being upgraded to LEDs, which emit way more cold/blue light which tricks insects. And they are dying. Which is a very, very serious problem. One of the biggest impacts of insect loss is on the many birds, reptiles, amphibians and fish that eat insects. If this food source is taken away, all these animals starve to death. 

Personally I have always hated the harsh white LED light, particularly outdoor. But my taste was probably not enough to influence the LED upgrades, which all have the benefits of significant energy savings. Now when the insects' problem has been identified, there is growing pressure to reduce both the light intensity and shift the spectrum back away from the white/blue tint. And the general awareness of the LED light pollution problem has grown significantly.

Cold white light is better for human safety. So it still should be available when necessary. So the long term solution becomes obvious: install dual-color, tunable-white lights coupled with occupancy sensors. Shine brighter/colder light only when needed (when the sensors report occupancy) and dim the lights, shifting the emission towards "warm" (yellowish) temperatures when no human occupancy is detected.

This poses some challenges with regards to the types of sensors used, as for outdoor lighting the conditions change a lot - temperatures can range from deep freezing to summer hot, there is precipitation, and the sensors must ignore animals and respond to presence of humans. The good news is the new generation sensors have already passed practical tests in not-so-mild locations like winter in Finland. And it turns out the "tunable white" technology, previously considered a luxury option for indoor human well being, may find an even bigger market of environmentally-friendly outdoor lighting.