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In all, we have one fewer lamp than before but we are able to illuminate a larger area while using 70% less Energy.

Matthias Künzli, Automation specialist
Matthias Künzli,

Automation specialist

The production site in Suhr has converted to LED lighting. And it is saving a lot of energy in the process. However, the most striking change has to do with something else, as a tour of the site reveals.

When the sun sets on Suhr AG, lights go on all over the Emmi site. “The 36 LED lights are controlled by an automatic timer,” explains Matthias Künzli, an automation specialist. “This means that sunrise and sunset times are calculated automatically for the whole year and the lights are controlled accordingly.” Matthias Künzli stands on the terrace of the plant, from where he can see almost the entire site. He is one of around 370 employees at the Emmi site in Suhr, which produces milk, cream and butter in three round-the-clock shifts. Matthias Künzli’s job does not involve dairy products directly, but rather the entire infrastructure including site lighting. “When the cables in our old sodium vapour lamps became brittle and other components also started to break after 30 years, we had to decide whether to repair them or install new ones,” explains Künzli.


Replace and optimise

It became clear to him that if the lighting was going to be replaced, then it should also bring other improvements – in more than one regard. “Lower energy consumption, lower costs, plus lower light emissions.” Künzli saw particular potential for improvement in larger areas such as the loading area of the logistics centre, where 22 large lorries can dock simultaneously while goods are loaded and unloaded. “Lighting an area that is nearly as large as a football pitch is no easy task,” says Künzli, pointing from the terrace to the vast site. In order to find out whether this was even realistic and what a new lighting system could look like, he contacted the lighting specialists at the EKZ, the power station of the canton of Zurich.

“The EKZ calculated how much energy and costs we could save by converting to LED. They also showed us that it would be possible to install lighting with LED floodlights and the existing lamp poles and how we could illuminate dark areas of the site with additional lamps,” says Matthias Künzli. It quickly became clear to him that repairs had resulted in a patchwork, which is why he advocated for installing new lighting. He admits that he had to do quite a bit of internal lobbying to get the job done. “Although installing new LED lighting costs 50% more than repairing the old system, the costs of LED are amortised after three to four years thanks to the energy savings.” In the end, this argument convinced everyone.


Nearly 75% in energy savings

Matthias Künzli implemented the new lighting concept in August 2016 with the help of a local electrician. “In all, we have one fewer lamp than before but we are able to illuminate a larger area while using 70% less energy. More than half of the energy savings, 42%, is attributable to LED. Emmi saves around 21% by using dimmers. “When the lights come on in the evening, they are at full intensity. At 11 p.m. we dim them to 70% and an hour later to 40%.” The lights are gradually dimmed over a period of five minutes so the change is hardly noticeable to the naked eye. “At 3 a.m. we increase the light intensity to 70% and one hour later to 100%, because that’s when operations at the site really pick up again,” explains Künzli. “Full light intensity is almost too bright in passageways, so we start with less light there and use about 7% less energy as a result. This amounts to total every savings of 70%,” he reckons.

Colourful, congenial and comprehensive

However, according to Künzli the most striking change has been colour recognition, which his colleagues cite in their abundant feedback. “The old sodium vapour lamps soaked the site in a yellowish-orange light. The pedestrian crossing between the employee car park and the site was barely visible in this light,” says Künzli, pointing straight down from the terrace. “Thanks to the LED floodlights, we can now recognise different colours in the dark – including the pedestrian crossing.” This is not just easier on the eyes. “It also affects your mood,” chuckles Künzli. “The light makes for a friendly reception when I arrive at the site. I feel welcome.”

Künzli also points out that from the terrace of the plant it is easy to see how evenly the light is distributed, in particular in the loading area where lorries dock. “We used to have light spots on the site and now the light covers the whole expanse.” The loading area is Künzli’s favourite place in the new light. His biggest “aha” moment happened in the slightly smaller employee car park: “I was astonished at how well an area of 70 by 30 metres can be illuminated with LED floodlights on 14-metre-high poles.”

According to Künzli, the entire site is generally better illuminated than before: It is almost impossible to find dark, dim spots anywhere. Above all, this benefits personal safety, Künzli explains during a tour of the various buildings on the site. “The light shines all the way into the corners. This makes pedestrians feel safer because they can see their environment better and also because lorry drivers can see them better.” The few dark spots that remain on the site were left that way intentionally, for example because they are not in a passageway and illuminating those areas would not make people safer. “We focused on optimizing the light in places where it makes sense,” asserts Künzli.


For the benefit of residents

However, from outside the Emmi site does not appear brighter than before because the conversion to LED also reduced light emissions. While sodium vapour lamps used to shine in all directions, the new LED lights are vectored, producing barely any light scatter. “The LEDs on our site are all directed to the inside, allowing us to avoid unwanted exterior light emissions.” According to Künzli, this is important because two sides of the site border on a residential area. “When you leave our site, it gets dark,” says Künzli. And he thinks that is a good thing.

After more than one-and-a-half years, Künzli draws a very positive conclusion. The new lighting has paid off – not just financially. He claims it only has advantages over the old lighting. “We anticipated most of the benefits.” But there were some surprises, too: “The new lighting needs to be cleaned much less frequently than before because spiders no longer spin their webs around it.”



TEXT Katia Soland (Elektrizitätswerke des Kantons Zürich)

PHOTOS Frank Schwarzbach