What Migros iced tea and refrigeration plants have in common

Through the entrance to the underground car park, we enter a room that is small but full of equipment, cables and pipes. It’s cramped and noisy, and the sounds change every few minutes. Measuring devices show temperature and pressure, and a number of other details light up on electronic displays. This is what the climate-friendly refrigeration plant looks like at the Migros shop in Lucerne’s Schweizerhof – rather gloomy, inconspicuous, and very technical.

Thomas Sigrist, Head of Building Technology Planning at the Migros Lucerne Cooperative, gives us a tour of the room together with refrigeration specialist Marcel Bärtsch, who developed the plant. In 2016, the cooling plant then in use was replaced prematurely even though it could have continued to run for a few more years – but only with a climate-damaging coolant. “Migros has been setting itself strict climate targets since 2010,” explains Thomas Sigrist. Just under ten years ago, customer requirements prompted an expansion of the chilled range, and with it a remodelling of the shop. “In view of our climate targets, switching to climate-friendly cooling was a logical step,” explains the building technology specialist. During the planning phase, he learned about the KliK Foundation’s supported programme from Marcel Bärtsch, which was extremely helpful – after all, long-term climate targets and businesses’ sustainability strategies alone do not pay for a new refrigeration plant. “Supported programmes play a key role in ensuring that investments in climate-friendly technologies are actually made,” says Thomas Sigrist.

The refrigeration plant for the Migros shop in the Schweizerhof works with the natural refrigerant CO₂. The special feature of the installation is a number of insulated valves arranged vertically one above the other. “These are so-called ejectors” explains refrigeration specialist Marcel Bärtsch, and they are used to increase the efficiency of the refrigeration plant. Before the CO₂ is transported via the pipes to the refrigeration units in the shop, it must be compressed (see info box for how the refrigeration unit works). Thanks to pre-compression of the gas, the ejectors ensure greater efficiency in further compression.

These days, such ejectors are standard in climate- friendly refrigeration plants with CO₂ as a refrigerant, explains Bärtsch. In 2016, when Migros was being remodelled, this technology was still quite new. “We deliberately wanted to take on a pioneering role,” emphasises Thomas Sigrist, adding: “We said to ourselves: if we’re going to do it, let’s do it properly. And that’s undoubtedly also an effect of the supported programme: new technologies are more likely to be used and can become established.”

Thomas Sigrist takes us from the somewhat cramped refrigeration plant room in the underground car park right up to the roof of the building. After a short climb up the roof ladder, we can see Lake Lucerne in the background. But Thomas Sigrist pays no attention to the view, pointing instead to the roof structure in front of it: a long rectangle with numerous fans. We are standing in front of the gas cooler. Marcel Bärtsch encourages us to touch two of the pipes on the structure one after the other. The first is warm, the second cool. He explains: “The warm refrigerant flows through the first pipe. Waste heat that cannot be utilised must be cooled via the gas cooler. This draws in the ambient air and uses it to cool the CO₂, which flows back to the refrigeration plant via the cool pipe.”

The Migros shop uses a large proportion of the waste heat generated by the refrigeration plant for heating. Thanks to the subsidies for climate-friendly cooling, Migros was able to increase the climate benefits at the Lucerne site even further and make the heat supply more sustainable with a new heat pump that is integrated into the refrigeration plant.

When asked how climate protection can be increased within businesses and specifically in the retail trade in future, refrigeration planner Marcel Bärtsch says: “Regulations are the most helpful.” He cites the federal Chemical Risk Reduction Ordinance (ORRChem) as an example, which will completely ban refrigerants with global warming potential (GWP) of 2,500 or more from 2030.

In terms of technology, Marcel Bärtsch sees the future primarily “in the combination and optimisation of different systems within the same building – such as the cooling and heating system here at Migros.” When the Schweizerhof shop was remodelled almost ten years ago, these kinds of system combinations were still in their infancy. Now things look very different: sustainability and climate protection are as much a part of the product range of many businesses in Switzerland as iced tea is to Migros.