di by Alejandro Sanchez, astrophysicist at University of Exeter (UK), and Cities at night’s project leader.

In general, the short answer is no.

In general, the short answer is NO. The long answer is, as, in almost everything, it depends. Contrary to what the vast majority of the population ignores, the implementation of LED outdoor lighting has been motivated more by business and political interests than sustainability. Until 2017 there were no LEDs in the outdoor lighting market that were as energy-efficient as high-pressure sodium. However, these have disappeared from the market for business interests. 

The Led manufacture is 70% more harmful in almost all indicators than current sodium lamps. More efficient than sodium LED lamps tend to have very high colour temperatures that cause severe damage to ecosystems, safety problems due to glare, and potential negative health effects.

Ultimately, LEDs can be sustainable, if when installed, the reduction in power offsets the impacts of their manufacture and does not generate other major problems in ecosystems. In 2017 we published an article in which it was shown that light emissions were increasing at a rate of 2.2% per year throughout the planet. This implies that the implementation of LEDs, far from helping global sustainability, is producing a rebound effect. In general, what we observe from organizations that fight against light pollution is that this is an issue ignored by most of the environmental community, both academic and environmental activism.

At the same time, we observe that nocturnal ecosystems and their most basic mechanisms are ignored: simple issues such as the disappearance of insects, the loss of pollinators, disorientation of migratory species, impacts on amphibians, drastic changes in the functioning of the prey-predator balance are affected by light pollution. But the number one excuse for the installation of LEDs is paradoxically the fight against light pollution and the fight against climate change. An example of this was the Milan City Council in 2014 when it changed all its public lighting. It changed the entire city, with LEDs less efficient than sodium lamps and only saving a small amount of energy,

but emitting the same light to the ground and 27% more blue light to space. Other cities such as Madrid also made a total change in lighting, but although 33% of the city switched to LED, the remaining 67% opted for a simple and flat reduction in power. Seven years later, practically no one in Madrid noticed the power reduction, but there were numerous complaints about the transition to LED due to its annoying whitish colour. The change in Madrid was the largest public lighting change operation in Europe, but it did not have an environmental report. Years later, the citizens asked the city council to carry out this evaluation a posteriori and, although we are convinced that the result will be positive, the project is in a drawer. Meanwhile, there are millionaire subsidies to install LEDs throughout the country (150 million last year in Spain). The worst of all is that many are not even aware of it and believe that they are really doing it well. That is why we need people who are dedicated to communication on sustainability issues professionally or as an activist to be aware of this problem. If used properly, LEDs can be a great asset in reducing CO2 emissions and light pollution. If used properly, the ability of LEDs to send light only where it is needed, the ability to choose the right colour, the ability to regulate the intensity, the ability to correct excessive lighting, the ability to change the colour of light dynamically.  Smart lighting is smart only when there are smart and trained professionals behind it.

We need lighting designers to adapt lighting to people's real needs, we need environmental impact reports that tell us that it can be illuminated and that it cannot be illuminated, we need engineers to offer us the best technical solutions. Eliminate one of those steps, and you can take it for granted that the result will be neither smart nor sustainable lighting, no matter how expensive and advanced the lighting system is. Part of the industry is starting to bet on a new strategy. If you don't want to convert to LED, we are going to force you. Small municipalities are beginning to have problems finding sodium lamps to maintain their lights and are forced to switch to LEDs without the necessary guarantees. On the other hand, the European Parliament has already asked the European Commission to carry out a regulation that limits the spread of light pollution. We are in a race to save the beauty of our cities, our cultural heritage, to save nocturnal ecosystems. But it is not as easy as it seems. LEDs can be sustainable, yes. They are by default, no. It is necessary to install sustainable lighting, make a proper environmental impact assessment, have a good lighting designer, good engineer, good control of the work done and finally measure, measure and measure. per adattare l’illuminazione alle reali esigenze delle persone, di rapporti sull’impatto ambientale che ci dicono cosa può essere illuminato e cosa no, e di ingegneri che possano offrire soluzioni tecniche vincenti. Eliminare uno di questi passaggi porta a una soluzione né intelligente né sostenibile, e questo a prescindere da quanto il sistema di illuminazione sia costoso o avanzato. Parte del settore sta iniziando a scommettere su una nuova strategia: forzare la conversione al Led. I piccoli comuni cominciano ad avere problemi a trovare lampade al sodio e sono costretti a passare al Led senza le necessarie garanzie. D’altro canto, il Parlamento europeo ha già chiesto alla Commissione europea di attuare un regolamento che limiti la diffusione dell’inquinamento luminoso. Siamo in corsa per salvare la bellezza delle nostre città, il nostro patrimonio culturale e gli ecosistemi notturni. Ma non è così semplice come si crede. I Led can actually tell if an installation is actually sustainable or not.