Matthias Künzli is actu­ally a specialist in automa­tion at dairy processor Emmi in Suhr, Switzer­land. However, in recent months, he has been working hard on another topic, one that is close to his hard: Modern­izing the ware­house cooling system in the logis­tics center to make it more energy effi­cient. “It has been in oper­a­tion for more than 20 years. It was there­fore clear that fail­ures and repairs would occur more frequently in the future. Aside from that, the entire system was simply no longer up to date,” he explains.

This is also due to the fact that, until a few years ago, in addi­tion to dairy prod­ucts, meat, eggs and vegeta­bles were stored and picked at the logis­tics site in Suhr. “Colder ambient temper­a­tures are required for these prod­ucts. As a result, the cooling capacity of the fans was primarily designed for this,” says Künzli. In recent years, the Suhr site has been expanded to become a center of excel­lence for milk and butter. “More precisely, liquid and fat,” explains Künzli.

A retrofit for demand-based cooling

At Emmi, sustain­ability has always played a key role and is also firmly anchored in the corpo­rate strategy. Based on its sustain­ability model and a net zero reduc­tion path, Emmi has set ambi­tious and scien­tif­i­cally supported targets for reducing green­house gas emis­sions. By 2027, it wants to reduce its own emis­sions (Scopes 1 and 2) by 60 percent. Energy effi­ciency is an impor­tant issue here. “We have been working on energy opti­miza­tion across all the media for over ten years: steam, water, gas, elec­tricity, every­where there are devel­op­ments that help us to save,” says Künzli. “With elec­tricity, the easiest way to deter­mine the savings is by doing a before/after measure­ment. This is why modern­iza­tion projects in this area can also be easily conveyed to manage­ment.”

We have been working on energy opti­miza­tion across all the media for over ten years. With elec­tricity, before/after measure­ment is easiest, so modern­iza­tion projects are easy to convey.

Matthias Künzli, specialist in automa­tion at EMMI

Matthias Künzli got to work and looked at the existing fans more closely. “I was shocked by the number of installed fans and their joint power. We no longer need this power when using the logis­tics center, but could not reduce it because it is not so easy to adjust the speed of the old fans,” he explains. “In addi­tion, the AC fans had very poor effi­ciency levels anyway.” Time for a compre­hen­sive retrofit!

No such thing as no can do

Matthias Künzli did not make things easy for himself. He metic­u­lously refined his list of installed fan types, performed consump­tion measure­ments, compared perfor­mance classes and volume flow rates and looked for part­ners to retrofit cooling units with energy effi­ciency. “I wanted state-of-the-art fans to be installed in existing devices,” he says. “The ceiling coolers are very robust and have few wearing parts. It is simply not sustain­able to throw them away.”

But most of the refrig­er­ator manu­fac­turers he asked recom­mended exactly this approach. When Künzli attended a seminar by ebm-papst in 2020, he was enthu­si­astic about the perfor­mance of modern EC fans, and also by the commit­ment of the employees at the ebm-papst subsidiary in Switzer­land. “They helped me with my project right from the start. There was no ‘that isn’t possible’,” says Künzli, who decided to retrofit his cooling system with fans from ebm-papst.

Good plan­ning pays off

As the retrofit was going to be performed during oper­a­tion, Matthias Künzli left nothing to chance during the prelim­i­nary plan­ning. Together with his deputy Arber Gashi, he disas­sem­bled one of every cooler type and equipped it with a fan from ebm-papst. “It was impor­tant that the cooling units were quickly ready for use again. The aim was also to deter­mine which brackets were neces­sary to attach the new fans to the existing ceiling cooler. I had them made in advance,” says Künzli.

It all started at the begin­ning of 2023: Nine coolers were each equipped with three AxiEco axial fans with guard grills for short nozzles. And 27 others, each with three HyBlade axial fans. Both versions make a great impres­sion, not only with their low energy require­ments, but also with their shallow instal­la­tion depth, low noise level and excel­lent effi­ciency. Measure­ments shortly after instal­la­tion show that the current draw per cooler has fallen from eight amperes to one ampere.

“We currently operate the fans via setpoint poten­tiome­ters with 50 percent power,” says Künzli. “If the maximum power require­ment is deter­mined in summer, the indi­vidual cooling units in the final assembly can then be indi­vid­u­ally controlled via setpoints from the PLC.”

A total of 69 evap­o­ra­tors at Emmi have been equipped with modern EC fans. 21 more are to follow in 2024. (Photo | ebm-papst)

After project comple­tion, Emmi expects to save 550,000 kilo­watt hours of elec­tricity per year. (Photo | ebm-papst)

Energy savings of over 80 percent

In addi­tion to the smooth conver­sion, Matthias Künzli is partic­u­larly pleased about the measur­able result of the retrofit: “ebm-papst promised us energy savings of around 50 percent. In fact, most fans give us more than 80 percent. Thanks to the fans’ effi­ciency, the 50 percent savings – and up to 30 more – mean that we have been able to gener­ally reduce the fan power.”

But it is not just the numbers that have inspired Künzli. “The new fans hardly make a sound. I had to take a look at the visu­al­iza­tion to see if they were actu­ally running,” he says with a smile. “At the logis­tics center, we have a loud­speaker system that plays back­ground music and messages during working hours. It can now finally be heard really well. That is good news for our employees.” After the retrofit, it has also been more pleasant for them, Künzli adds: “Before, we distrib­uted the cooled air via textile hoses in the hall. It was time-consuming and gener­ated an air draft. But now the employees almost no longer feel it. We may consider removing the textile hoses completely in some areas.”

ebm-papst promised us energy savings of around 50 percent. In fact, most fans give us more than 80 percent.

Matthias Künzli, specialist in automa­tion at EMMI

Two floors were fitted with new fans in the four-story logis­tics center by March 2023. The 21 coolers in the base­ment are still to come, with another 78 fans. “We can only perform the replace­ment in winter 2024 because we have to rely on cool ambient temper­a­tures again,” says Matthias Künzli, who is already looking forward to it. “When the entire project is completed in spring 2024, we will have a total of 206 new fans in oper­a­tion and, according to current calcu­la­tions, save around 550,000 kilo­watt hours of elec­tricity per year.” That is around 200 metric tons of CO_2.