The switch to exterior LED lighting has been completely counterproductive


Panhandle of Florida at night. (Image: NASA / JSC)

To reduce energy consumption, many jurisdictions around the world are making the transition to outdoor LED lighting. But as new research shows, this solid state solution has not produced the expected energy savings, and possibly worse, has resulted in more light pollution than ever before.

Using satellite-based sensors, an international team of scientists sought to understand if the surface of our planet becomes brighter or darker at night, and to determine if LEDs are saving energy on a global scale. With the introduction of solid-state lighting, such as LED, OLED and PLED, it was thought (and expected) that the transition to conventional electric filaments such as electric lighting, gas and plasma would generate large energy savings. According to the latest research, however, the use of LEDs has resulted in a "rebound" effect by which many jurisdictions have chosen to use even plus light due to the badociated energy savings.

In fact, as new results show, the amount of outdoor lighting around the world has increased in recent years. "As a result, the world has experienced a" generalized loss of night, with half of Europe and a quarter of North America experiencing substantially modified light-dark cycles, "the researchers write in the new study, which was published today in Scientific Advances .

This conclusion was reached after badyzing high resolution images compiled by the Day-Night-Band (DNB) instrument on board the Suomi NPP meteorological satellite. This sensor has a spatial resolution of 2,460 feet (750 meters), and can "see" light in the range of 500-900 nm (humans see in the range of 400-700 nm). Traditional lamps emit some infrared that the DNB can detect, and the LEDs produce a large amount of blue light that the sensor can not see. Then, as cities change their exterior lights to LEDs, scientists often see decreases in the light observed by satellite (which, to the human eye, seems to have the same brightness).

"For that reason I expected rich countries to do so, it seems to be getting dark (even if that were not the case), instead we observe that rich countries remain constant or, in many cases, increase," said Christopher Kyba, author principal of the study and researcher of the German Research Center of GFZ for Geosciences, in an interview with Gizmodo. "That means that although some cities are saving energy by switching to LED, other places become brighter by installing new or brighter lamps (which need new energy), so the data does not match the hypothesis that, on a global scale, LEDs save energy for outdoor lighting applications. "

Image: Carla Schaffer / AAAS

Researchers have been documenting the steady growth of artificial lighting since then it was invented, and they have been wondering when it could stop the trend. During the second half of the 20th century, electric light grew at an estimated rate of 3 to 6 percent per year. According to the new study, the artificially lit outdoor areas of the Earth grew by 2.2 percent each year between 2012 and 2015, with a total radiance growth of 1.8 percent each year. During this period, almost 60 countries experienced rapid increases in nighttime lighting between 110 to 150 percent, while another 20 countries experienced growth rates of up to 150 percent or more. Almost 40 remained stable, with only 16 countries experiencing decreasing night-lighting rates.

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Needless to say, and as Kyba pointed out, these rates were not consistent across the globe. In developed countries such as the United States and Spain, lighting rates remained stable, but most nations in South America, Africa and Asia experienced growth. In countries devastated by war, such as Syria and Yemen, the rates of outdoor lighting decreased. The new study shows that, with regard to night lighting, most of the world is still playing to meet the standards of exterior lighting of the First World.

"This study … validates … two things that we have suspected: that the growth rate of light pollution continues upwards on a global scale, and that the migration of outdoor lighting from older technologies to LED is not having the anticipated benefits in terms of global reductions in energy use. "

It is disturbing that the results presented in the new study are actually worse than the data suggest. As mentioned earlier, DRB can not detect low-wavelength blue light, which humans can see. Our planet, therefore, is even brighter at night than the data suggest.

"This study is important because it validates with data two things that we suspect: that the growth rate of light pollution continues upwards on a global scale, and that the migration of exterior lighting from older technologies to LED is not having the anticipated benefit in terms of overall reductions in energy use, "John Barentine, a resident physicist at the International Dark-Sky Association, told Gizmodo. "The last point is especially important because several governments have been convinced to convert their outdoor lighting to LED based on promised reductions in energy use."

Barentine, who was not involved in the new study, says that the cost savings of improving the energy efficiency of LED lighting has been directed towards the deployment of more lighting and with significant environmental consequences, both in terms of light pollution as well as carbon emissions.


Satellite images of Calgary, Alberta, taken from the ISS in 2010 and 2015. Many areas in the suburbs were recently lit compared to 2010, and many neighborhoods switched from orange sodium lamps to LED lamps white (Image: Earth Sciences and Remote Sensing Unit, NASA Johnson Space Center)

"It is not hyperbole to describe the global problem of light pollution as unprecedented and surprising," he said. "Beyond the energy problem, the main environmental impact of artificial light at night is the health and well-being of virtually all organisms on Earth, including humans."

Night lighting is considered a serious environmental pollutant that disrupts nocturnal animals, plants and microorganisms. But it is also bad for human health because it interrupts the biological circadian rhythm, leading to metabolic disorders.

Thomas Davies, community ecologist at the University of Exeter, who is not affiliated with the new study, says it is no secret that nighttime artificial light is a widespread pollutant, but estimate the speed at which it is expanding It has been a technical challenge. [19659003] "This research overcomes many of these technical problems by providing reliable estimates of the rate of global expansion in artificial light pollution," Davies told Gizmodo. "The figures are truly impressive, given that we know that illuminating the night environment can have widespread ramifications for the environment and human health."

Barentine says that the solution to this problem is quite simple, but it will gradually require us to change our relationship with light at night.

"We could instantly reduce the problem by half if we guarantee that all outdoor lighting lamps are fully shielded, which means they did not emit light directly on the horizon," he said. Gizmodo "We could further reduce the amount of light pollution in the world if the luminaries are designed and installed properly so that the light they emit is limited to the task area and is not provided in greater intensity than necessary to illuminate the task so Finally, we could reduce the biological damage to our lights by making sure they emit as little short wavelength (blue) light as possible, choosing "warmer" lamps.

The most effective way to achieve these changes it is through public policy, says Barentine, so we should encourage codification of these principles in local, regional and national laws throughout the world.

These solutions seem simple, and certainly sensible, but it is more convenient for those of we in the developed world to impose such high standards in places where night light is being used for the first time. We need to change the culture around the use of external light, but let's start this conversation in places where we already take night lighting for granted.

[Scientific Advances]

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