"LED technology is an opportunity to illuminate less in a more targeted way. Because light is not needed everywhere."
In one of the most beautiful baroque cities in Switzerland, Daniel Odermatt (Head of Networks at Regio Energie Solothurn) took us on a journey through time of public lighting. For once, the tour did not start with the latest LED lights, but with a light column from the 14th century, which still stands today in the old town of Solothurn. Along the way, we experienced the different eras of lighting - from the first "light pillar" to gas lights to the electric models. Many of these relics from the past have been upgraded with modern technology - but have retained their historic form
Development of public lighting Solothurn 1550-2021
Solothurn is one of the pioneers when it comes to refurbishing street lighting and reducing light pollution. The first LED luminaires were installed and tested in the city on the Aare as early as 2008 - even before the big LED boom.
"The first LEDs were indeed more efficient - but this was at 5600 K. The bluish light was "nothing beautiful". I'm glad, we have decided in in our renovation concept at that time, that we take it slowly and had not converted everything immediately."
Daniel Odermatt
Head of networks, Regio Energie Solothurn
Why Solothurn is only slowly but gradually refurbishing its lighting to LED, with which measures they have already been committed to reducing light pollution for years and why they are one of the first Swiss cities to rely on the CO2-compensated luminaires, Daniel Odermatt tells in conversation with Peter Schwägli (Managing Director Smart City and Light, ELEKTRON AG).
Daniel, you are responsible since 2007 for about 7000 light points in Solothurn as well as in some surrounding communities. What do you like so much about this job?
The versatility: lighting is about technology, design - and it "Mänschelet" very much. Everyone speaks with and has his opinion, which light color is the most beautiful, what is too much and too little light. That's exactly the big challenge. But that's exactly why it's very versatile and exciting.
A lot has changed in the lighting industry since 2007. After initial difficulties, LED technology has become the standard and established. The efficiency has improved greatly. How did you perceive this development as an operator?
The range of luminaires exploded in the early days back then. When I started, there were sodium vapor lamps, which was "the thing." You could screw in a 50 or 100 watt bulb and that was it. With LED, suddenly everyone became a luminaire manufacturer. The difficulty was to keep track of everything that was available. That was a big challenge and very time-consuming.
How did you get an overview?
At some point, we just stopped receiving sellers (laughs). No - in those early days, we did a lot of trials - and also quickly saw big differences. We installed and tested around 30 sample luminaires and retrofit kits from 2008-2010. After a few months, about half of them dropped out. So we got an overview through tests and sampling. The very first tests I did at that time were with the LED components of the new Christmas lighting.
About Christmas lighting to LED street lighting?
In fact, the LED renovation in Solothurn began back in 2007 with the planning and implementation of the new Christmas lighting (laughs). In street lighting, LED lights were not yet a big topic at that time. In 2011, we started installing the first LED lights in some quarters of the city, at that time still with the 4000 K light color. However, we quickly realized that even this light color was too bright. That's why we took our time with the further refurbishment. Today we use 3000 K everywhere.
This means that light pollution is increasing, although we actually have more precision today with the latest lighting technology?
Yes, it tends to be today simply more illuminated*. One has indeed improved energy efficiency and can make a directional lighting. But overall, there are just in the private sector much more lights such as lights with motion sensors, small spotlights and spots. And that used to be less the case. Another danger I see is the lifespan of LED luminaires. We still have luminaires installed today that have been in operation for 60 years. You had to change a lamp in between, that's all. What I'm afraid of is that the "fully encapsulated" LED luminaires will no longer work after ten years and you'll have to replace them completely. And that is not purposeful in terms of sustainability.
...the tendency that we perceive from the manufacturer's side is today again moving away from "fully bonded" luminaires to luminaires that can be maintained again. Is this also already an issue with you?
This is a must. This is also the reason why we do not simply take the cheapest luminaire and rely on the products of ELEKTRON. That clearly distinguishes you from other manufacturers that you offer such a thing. Luminaire bodies last 50 years without any problems and must be easy to maintain. If, for example, the driver has to be replaced after 15 years, it must be possible without much effort.
It was indeed in the early days of LED lights a big challenge of manufacturers, to what extent you can repair lights at all during operation. Especially the ESD protection and driver tuning were a big issue...
With you it was actually always so that you could replace and change individual components. And now with the generation 2 of the Luma has become even more professionalized and even easier. You can get to the individual parts in just a few steps and replace them easily. And that's the right way to go, I'm convinced of that.
Ecology is on everyone's lips and in the media every day. It is also gaining importance for us in outdoor lighting. "Only cut down as many trees as can grow back", or in other words, dealing sustainably with our earth is important. What influence does the development towards more sustainability have on your daily work?
This is a very important concern for me, and not only for me. In the past, it was said "a technical luminaire must give the right light" and done. Today we look specifically to have only a minimum of light to cover the needs. That means ensuring road safety and complying with standards - but certainly not more light than necessary.
Unfortunately, we still use too much. Light is not needed everywhere. It is not a must everywhere.
It's important to me to push this issue further, like with your CO2 compensation that you offer.I think that's very good and I think it will occupy us much more in the future. People are also much more interested in it today.
Also in Solothurn, there was already a proposal in the municipal council on the subject of the environment, how much you have to light in the city at night...
.Exactly, night shutdown was already an issue, the proposal was mainly in terms of reducing energy consumption and costs. However, in the course of LED development, the issue has moved into the background, because energy consumption has already been reduced enormously anyway. Today with the new standards, we are going the way of dimming at night, not switching off. And as far as we can, so that the standards are met.
Always in the discussion is also the topic of the illumination of monuments, buildings, such as here, for example, the cathedral. The opinions go here very strongly apart. Is it still legitimate to make Anstrahlungen?
This is a very subjective question. I think it still has its justification. Today, you can make the spotlighting very intelligent, by really only spotlighting the object with little stray light. We will also address this issue in Solothurn and evaluate the existing illuminations, especially with regard to light pollution. We basically don't have many buildings, the most prominent being the St. Ursen Cathedral, which stands out. Here, the outcry would certainly be very great if it were no longer illuminated at all.
According to the evaluation, light pollution has decreased in Solothurn in recent years. That is certainly also your merit. However, the city is rather in the midfield in the Swiss city comparison. Where do you see as the person responsible for the city lighting still potential to reduce light pollution?
We have different scenarios. In Solothurn, we have always successively "usgstaubet" the oldest, most inefficient lights. And that's why we don't have everything on LED yet. But we are continuously working on it and renew every year about 5-10% of the lighting. This also reduces light pollution year after year. On the other hand, more and more roads are being built, which then also have to be illuminated. In addition, there is also in the private sector because of the diverse application of LED lights, there is more light pollution.
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That's the cue for the next question: light pollution in other areas that you perceive. Are there also possible measures outside your area of responsibility?
As already mentioned, I see a lot of potential in the private sector. An example: We always have the Räbeliechtliumzug, where the children run on a Thursday evening with their Räbli through the old town. I always turn off the street lighting in the old town. Unfortunately, the effect is small, because the shop windows shine so brightly. Shop window lighting certainly has its justification. But I see no reason why they have to be on at night. On the other hand, there are also large companies with their impressive buildings, which they illuminate completely all night. I'm certainly sensitized to these issues as well, which is why I notice it. It would be nice if everyone would just think a little more and contribute to it. We can't influence everything. But where we can, we try to do it as well as possible.
The influence of outdoor lighting on flora and fauna is now obvious: light has a negative impact on nocturnal insects and thus on our biodiversity. Nocturnal animals and insects are attracted to artificial light. Have you also noticed this and what possibilities do you see to counteract this?
Yes, there is the possibility of choosing a different light color such as amber, which is gentler on insects. In places where this is really an issue, I think you should have the courage to turn off the lights at night or reduce them to a minimum. That's still something that the standards almost don't allow. One is currently only allowed to reduce two levels in the lighting class.
On the subject of "blue content", which we have been dealing with for years, research is unanimous that this is not beneficial for the animals...
.This is partly a reason why we here Solothurn at the beginning still very reluctant to enter the LED conversion. The first LED lights were efficient, but also at 5600 K with very high blue light. But that was "nothing nice". I'm glad, we decided in our concept back then, that we would take it slowly and not have everything converted immediately. Because that way we can incorporate new findings again and adapt our concept, for example in the choice of light color. There, it is important for us that there is a certain uniformity. So today we basically use 3000 K, whereas in the beginning it was 4000 K. In the Aare region, we can also imagine working with even lower color temperatures, for example with amber.
"For me also a great concern is the possibility to mount additional apertures. In the LED world of manufacturers, you sometimes meet with incomprehension, because you already have "directed light" with the LED lights. But for certain places, such as bridges, an additional aperture is needed. In addition, we can also show people that we are doing something against stray light. Apertures are a visible sign, so to speak."
You mentioned it: We started at the beginning of 2021 with the climate-neutral luminaire project, which you are also involved in. Are there other projects to reduce CO2 at RegioEnergie?
We do very much and are of course eager to push the issue. We are active in the field of biogas and biogas sales. Our electricity products are CO2 neutral. In addition, we have expanded a large district heating network, which saves about 14,000 tons of CO2 per year.
What do you see as the biggest challenge in the future in your everyday life as the city's lighting manager?
A big challenge will be that we bring all the new possibilities under one hat, by that I mean "smart" technologies. To be able to use everything, it takes time. And no one has that anymore today. We have now also equipped the first luminaires with light controllers, but there is currently still a bit of a lack of time to use all the information.
You say there is a lack of time. The idea is that the system should save time in everyday life. That is actually the added value that should have such a system...
.I can imagine this well in the future, especially in maintenance. If the luminaire itself reports when it is defective and we quickly get the spare part, that is of course a great advantage. I think the challenge is to tackle these development steps. We are also experiencing digitalization in the electricity grid, gas supply, district heating... and today you are virtually bombarded with systems and apps. You have to make sure that people don't get lost in the digitalization process.
I agree with you. We have digitization on all levels - where there is a big vision to have everything on one platform and not many individual systems. That's why it's important that the systems are open to communicate with third party systems via an interface.
"Es isch defür und de wider". You simply must not underestimate the complexity and the benefit for customers or operators must be apparent. Currently, we still produce a lot of data that we store but do not really use. We want to plan this development for the long term so that we don't bet on the wrong horse. That's why we always prefer to wait a little at the beginning.
In conclusion, are there any topics and suggestions that you would like to share with the luminaire industry?
.The topic of standards is already a concern for me. Today one secures oneself very strongly, already in the light planning. One illuminates up to every corner perfectly - but often forgets aspects such as trees and the like, which also have an influence. I think it's a shame that standardization tends to make the streets more lit. I think one should focus again on delicate zones, such as pedestrian crossings. These are much more visible if they were strongly lit and the other street lighting reduced accordingly.
The second thing I'd like to note is: the directional light sometimes causes a "tunnel effect" - it's completely dark to the left and right of paths. Especially for bike and pedestrian paths, this can cause discomfort. Sometimes it just takes a little diffused light to ensure the safety and well-being of our citizens.
A phenomenon we have also heard from other customers. It's about finding the right mix around the tasks that artificial light has in the outdoor area: Conveying safety, creating aesthetics as well as atmosphere, and thus intentionally promoting social life. This also includes consciously opting for a little scattered light so that people feel comfortable. It is the art to weigh, how much scattered light has justification.
.A big thank you to Daniel Odermatt for the exciting insight into his daily work and the development of public lighting in Solothurn.
About Regio Energie Solothurn
We are the first point of contact in the Solothurn area in the fields of energy, water, energy efficiency and building technology. We accompany our clientele through the energy transition and develop modern, decentralized solutions with environmentally friendly energy sources.
