Technology reutilisation helps optimise energy in super markets

Running a supermarket requires a lot of electricity. Long rows of refrigerators have to be kept cool and large areas have to be lit. A new concept enables supermarket operators to cut their energy use by around 25 per cent.

Cold air flows out of the long rows of shelves filled with sausages, dairy products and fish. Numerous lamps light up the space where daylight barely penetrates. Supermarkets use nearly ten times the energy of a normal household.

Researchers at the Fraunhofer Institute for Solar Energy Systems (ISE) in Freiburg, Germany, have now created alternatives. ''We have developed an integrated concept in collaboration with property developers, the planning team and manufacturers and  as a result, we aim to reduce energy consumption by 25 per cent in comparison to regular supermarkets'', says Nicolas Réhault, Group Leader at ISE.

The main focus of the concept lies in the area of cooling. This is because at approximately 40 to 50 per cent, it represents the largest share of the electricity bill.

The freezer-systems have to reliably store pizza, cake, fish, etc. at minus (-) 25° Celsius, otherwise the goods will spoil. Sausages and cheese must be stored at a maximum of four degrees Celsius. Normally, plug-in freezers are used for this purpose. They generate the required level of refrigeration themselves and pump the produced heat directly into the store – a practical but inefficient method.

ISE researchers have now developed a combined central refrigeration system in collaboration with property developers and the planning team. Now, all cooling points are connected to a combined central refrigeration system. The heat is not dissipated into the store but channeled via a three-stage recooling system. During the winter the system recovers the heat via a heat exchanger and uses it to heat the store.