Jasmin Jouhar: Food is a particularly sensitive kind of good. What does that mean for lighting?

Ralf Knorrenschild: As a consumer I want to be able to clearly see the goods and be able to assess their quality. Which is why the food needs to be illuminated as naturally and as true to life as possible. In the field of supermarkets we are already using about 90 percent LED lighting, which has the advantage that fresh goods such as fruit and vegetables, meat and cold cuts do not get damaged by the heat the light emits. Goods get neither too warm nor do they wilt the way they used to back in the days of UV radiation from discharge lamps. LEDs offer more sparing light.

How important is the color of the light in this regard?

Ralf Knorrenschild: It’s crucial, of course, because fruit and vegetables require a different light color than does ham, cheese or bread if they are to look appealing. At Zumtobel we also offer luminaires featuring a special technology that we call “Tunable Food”. You can use it to calibrate the luminaire itself to get the light color you need in the particular setting. If a supermarket then rearranges its product shelving you no longer need to reinstall all the lights; you can simply adjust the luminaires in terms of light color and color rendering to meet the new requirements. That amounts to maximizing flexibility.

You recently advised the architects at LAB5 on a new Interspar outlet in Budapest. What did the lighting concept involve?

Ralf Knorrenschild: The concept was designed to respond to local conditions, above all customer demand. The regional linkage is in general very important for supermarkets. On this project the focus was, for example, on giving the wine section a very special atmosphere as this has proved to be critically important in Budapest in the past. The new building was to support this atmosphere all the more: The idea was for customers to feel good, to enjoy a mood more akin to a small wine store. A closed-off section was designed, clad with curved wooden blinds, lending the interior a natural or at least close-to-nature and haptic touch. The LED luminaires and spots, which provide light to specifically support this tone, were positioned discreetly, indeed almost invisibly, between the blinds.

If the lighting is so well integrated, then I assume you were obviously included in the planning from an early stage?

Ralf Knorrenschild: The earlier we are included in the planning process the better we can integrate the lighting into the concept. In general, the sooner the different trades start coordinating with one another, the better. We all know the phenomenon from house building. When you move into a new home and a single cable is hanging from the middle of the ceiling in the living room, then you have far less ways of creating moods or highlights with your choice of lighting. It’s better to be able to say in advance where you want cables in the ceiling, walls or floor... and the same applies to a supermarket. We tend to host a workshop with the architect and store builders and explore what the exact wishes are. And then we develop various possible scenarios to fit the bill.

Alongside the wine section, what tasks does light otherwise perform in the Interspar in Budapest?

Ralf Knorrenschild: Often, the fresh produce section is the calling card of a food retailer. Not just because this section is highly profitable, but because high-grade fruit and vegetables presented in the right way enhance the overall impact the store makes, especially as the section is frequently located at the entrance. It was an important focus of the Budapest project, too.

So what types of luminaires did you go for?

Ralf Knorrenschild: Strip lights are inserted in the typical lines of shelves, running down the middle between the shelves and featuring extremely efficient LEDs. As a result, the shelves are bright across their entire height, the lighting even, and customers can therefore easily find their way to what they want: The price labels and even the small print on the packaging are legible. In addition, at several points in the supermarket we went for highlighting, for example at the freezers, for the dairy products, and at the fronts of the shelves, where articles in special sales drives get placed. There, individual spotlights emphasize the lighting. This is where customers decide whether to go down a line of shelves or not. By contrast, in the cafeteria we relied on atmospheric light, as the idea is to persuade customers to tarry a while here and slow down, as it were.

What are the three biggest mistakes you can make when illuminating food?

Ralf Knorrenschild: You must only minimally distort the true color of cooked and raw meats, for example. In Germany there’s even legislation on this, the “Boiled Sausage Decree”. Customers expect authentic products, which is why any distortion would be a major mistake. Moreover, dazzle should be reduced so that customers can find their way round easily. It would be bad if huge spotlights put me center stage as if I were in a studio and I then can’t see much, if at all. And needless to say, light mustn’t damage the goods or influence them negatively. Which is why butchers used to pass a slice of salami over the counter to kids, as the goods quickly lost the original color and no longer looked tasty.

The brighter a store the better?

Ralf Knorrenschild: Not necessarily. Positioning is the key: Is it a discount store or a supermarket? Customers then know immediately what quality to expect and what product assortments. A coherent concept is much more important than the simple strength of the lighting – starting with the outside.

How do lighting concepts for discount stores differ from those for supermarkets with higher-grade assortments?

Ralf Knorrenschild: Discount stores such as Penny, Aldi or Lidl tend to rely on diffuse general illumination, with few highlights or emphasized areas. In them, the customers themselves tend to take the goods out of the boxes. The clear message: Things here are simple and cheap. By contrast, in supermarkets the focus is on persuading customers to stay longer. There are restaurants, advice at the cheese counter, freshly baked bread and the like. So the lighting is more elaborate than in discount stores. Backlit shelves are a great device here, as they enable you to present the goods more attractively. More important than even brightness is accenting, specifically calibrated light, mood and ambience.

On the topic of energy consumption – is there scope to save more?

Ralf Knorrenschild: In France it is long since the norm to work with skylights mixing daylight and artificial light depending on the time of day. Thanks to LEDs we are already using about 50 percent less energy compared to conventional lighting, with the same volume of light and usually a better quality. The new systems tend to have a lifetime of about 50,000 hours, or 12-15 years in a supermarket.

As regards lighting, a lot is a matter of subjective perception, i.e., whether it appeals to a customer or not. Is it possible to view these things objectively, cast shelves in the right light?

Ralf Knorrenschild: There are no general rules, of course. We conducted a study on perception and developed target-group-specific illumination on that basis. The study is called “Limbic Lighting” and shows that a lighting concept tailored to your target group can boost sales. We found out that decisions are taken subconsciously: If I feel good and, even subconsciously, do not feel stress, then I stay longer and am more in the mood to buy something than if the setting influences me negatively, puts me under stress.

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