Insulated glass doors on cooling shelves save 40 to 60 percent energy


Interview with Peter Ebbing, Regional Director for Germany and Northern Europe at REMIS, Cologne, Germany

Now that the freezers are completed, the cooling shelves are next. This is how Peter Ebbing describes the changeover status of refrigeration units in the food trade. Cooler covers save energy and hardly bother customers. Doors for cooling shelves can also significantly reduce electricity costs, but with large customer volumes, retail is skeptical. Ebbing has worked for more than ten years for the German special-purpose glass manufacturer REMIS. The company retrofits old chest freezers and is a supplier for manufacturers of refrigeration equipment.

How far along is food retailing when it comes to changing its refrigeration units over to closed chest freezers and shelves?

The changeover to closed freezers in Germany has been completed 80 to 90 percent. Almost all supermarket chains use refrigeration units with covers in their new marketplaces. The percentage of open refrigeration systems abroad is even higher. However, a trend towards retrofitting covers or using new refrigeration units with glass lids is clearly noticeable.

It is a little different when it comes to doors for cooling shelves. Germany is only at the beginning here. There are already supermarket chains that always use doors. Kaisers-Tengelmann, Tegut and Rewe are trailblazers. In addition, there are many test installations to check the impact on energy savings and sales. Discounters only use doors for meat cooling racks. There are still some strong reservations about possible applications of closed refrigeration units.

The situation is similar in the other European markets. In France, food retail has decided on a commitment to use doors. In the Netherlands, the percentage of closed shelving due to regional requirements is already very high. There is also a clear trend towards using refrigerator door systems.

Why do discounters have a harder time with this? Do you also see a rethinking here? Who is a trailblazer?

Discounters have a limited assortment of goods and large customer traffic. When you have many customers, the practical use of doors is more difficult. At the same time, goods have to be restocked very frequently. Because of these general conditions, no discount store is comprehensively using doors yet. Perhaps joint special solutions would have to be developed for this.



How do sales figures develop if a retailer changes over?

Customer acceptance for doors is very high and there is no noticeable negative impact on sales figures.

What energy savings are possible? How often is a door being opened per hour?

Energy savings strongly depend on customer frequency. On a Saturday morning, the opening cycle can be approximately 60 times per hour, depending on the product. At other times, the shelves are predominantly closed. The spectrum of energy savings with the use of insulated glass doors is approx. 40 to 60 percent compared to an open shelf.

When should you invest in new freezers, shelves or refrigerators?

Depending on their condition, freezers and shelves have a service life of eight to ten years. Newer refrigeration units are being retrofitted.

What should retail pay attention to when choosing the appropriate cover? Are there thermal resistances, standards or energy efficiency categories? Which glass types are available?

There are specifications, for instance to always use ESG safety glass. Generally, the systems should be matched to the refrigeration units to ensure high energy savings at a simultaneous condensation resistance. It is recommendable for door systems to use insulated glass with a high UG value. We recommend <= 1.7 W/m2 x K.



What is state of the art in antireflection coatings?

Antireflection coating of glass improves merchandise presentation. Quadruple anti-reflective coating is the best available technology. That is to say, all insulted glass sides are non-reflective. However, the additional charge for antireflection coating is very high due to the complex production method.

How do you keep glass surfaces from fogging up?

An optimal adaptation design is important. All components have to be thermally insulated and cannot form a thermal bridge. For horizontal glass covers, the refrigeration units have to be retrofitted for closed operation. You achieve this for instance by reducing air speeds and temperature control. Only the use of insulated glazing with a special glass design facilitates high condensation resistance door systems.

One customer bothers another at the freezer because of the sliding doors. How can this problem be reduced?

There are vertical sliding closure panels available to avoid this problem. The glass panel is opened in a vertical direction and closed again towards the customer. With this system, the items can be taken out without bothering other customers.

Interview by René Schellbach,



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