Beautiful light with a sustainable impact

Proper lighting is an art, not just in the theater but also in retail spaces. The luxurious Jemoli Department Store in Zurich is a prime example. It displays its merchandise to best advantage using nearly two-thirds less energy than with its old lights.

How do you light a loafer? The question seems simple enough, but it’s actually anything but. Especially when the shoe in question is one of over two million products that need to appear in their best light to attract customers’ attention.

When it comes to lighting retail spaces, very different philosophies apply. Some store owners deliberately choose a dark setting in which they can strategically position accent lighting. Others prefer to display their merchandise in radiant light. According to Andreas Hartwig, Lighting Designer for Siemens, there’s no hard-and-fast rule for lighting retail spaces. “Ultimately, it’s all in the eyes of the beholder.” Nevertheless, the tendency in shopping centers is to overdo brightness: “The stores want to outdo one another, which always means using more light,” says Hartwig. “This consumes an unnecessarily large amount of energy and doesn’t necessarily increase sales.”

Lighting affects ambiance

There’s no doubt that lighting influences the mood of a room. Ambiance is affected not only by brightness, but also by color temperature, which is measured in Kelvin: Warm light with a relatively high red component – and a low Kelvin temperature – has a warm and comforting effect. That’s why, for example, “warm” white light is so popular for domestic living rooms. Cooler color temperatures with a higher Kelvin number have a different effect. They create a more sober atmosphere that promotes alertness.

The ultimate goal of lighting is to combine a positive shopping experience with an optimal presentation of merchandise.
Andreas Hartwig, Lighting Designer at Siemens

The play of light and color is part of the standard repertoire of a professional lighting designer. The craft originated in the theater, and it’s no coincidence that the lighting of merchandise is called staging. “Basically, the same principles apply to retail spaces as to stage lighting,” Hartwig explains.


But there’s one important difference: Whereas the focus in a theater is generally on the action on stage, the sheer number of products in a department store naturally puts limits on the lighting. It would be impossible to stage each individual product like in the theater. In addition, displaying merchandise in the best light isn’t the only purpose of retail lighting. It’s also supposed to make the building easier to navigate and promote the well-being of employees and customers. “The ultimate goal of lighting is to combine a positive shopping experience with an optimal presentation of merchandise,” Hartwig concludes.

Two million items, one lighting system

With this goal in mind, Hartwig and his colleagues developed a new lighting concept for one of Switzerland’s most prestigious department stores: the Jelmoli Department Store in the heart of Zurich, which offers roughly two million items on six floors. The building’s lighting was outdated. The old gas-discharge lamps, which generate a continuous arc between two electrodes, were no longer state-of-the-art and required frequent maintenance. An on-site analysis revealed additional opportunities for improvement: “In the past, Jelmoli didn’t have uniform lighting,” says Hartwig. Different color temperatures were implemented in stages. Some floors were lit to a temperature of 4,000 Kelvin, while others were significantly warmer at 3,000 Kelvin. “When you take an escalator from a cool white floor to a warm white floor, your eyes first have to adjust to the new color temperature,” Hartwig says. “In the first moments after such an extreme temperature change, you’re too aware of the light’s red component.” The result: For a few seconds, your surroundings take on an unnatural orange hue.

The new lighting would no longer generate these effects and would provide a uniform impression. “Thanks to latest LED technology, we were able to employ a mixed temperature of 3,500 Kelvin from the first to the fourth floors,” says Hartwig. The new solution is ideal for lighting almost all product categories, from white shirts to silver mixing spoons to bright-red bikinis.


To bathe the retail spaces in even, consistent light, Hartwig and his colleagues also modified the luminance: Wall lighting and product lighting were coordinated with one another. This served to improve contrast ratios, increase clarity, and facilitate navigation. “We also lowered the illuminance to a sensible level,” says Hartwig. “Now the focus is no longer on pure brightness but on a good distribution of light within the space.”


Lower light? Nothing but a color temperature? Jelmoli management was initially skeptical of the recommendations in Hartwig’s design. The new concept was first put through its paces with about 60 lights in a mockup space in the department store. “We grabbed all kinds of merchandise from the store and looked at it under the new light,” Hartwig reports. The concept was fine-tuned in close collaboration with the operators and owners.

Once all the details were settled, the conversion began. Some 9,000 lights were retrofitted in just a few weeks. The results are clear to see. “The lighting of the new solution is much whiter and is compatible with a wide range of product categories. So in the future we’ll be able to design more freely and, for example, decorate with richer colors and add accents,” says Jelmoli’s chief decorator Lars Jöge. 

More efficient lighting requires less cooling

Given the aesthetic benefits of the new lighting, it’s easy to forget that the project had a very different origin: Siemens engineers were engaged to assess the department store for its energy optimization potential. Their analyses revealed that the operators could achieve massive savings in three areas: ventilation, cooling, and lighting. In the third area alone, conversion to the latest LED technology delivered significant savings: “The new lights consume 60 percent less energy than the old ones,” says Hartwig. It was possible to reduce the connected load of the lighting system by several hundred kilowatts.


At the same time, the more efficient lighting has also had a positive influence on the other building services examined: “The new bulbs give off less heat, which allowed us to design more economical ventilation and cooling systems,” Hartwig explains. Examining the three areas together paid off, because otherwise the hidden savings potential would have been missed.

Optimized ventilation and cooling

In addition to the lighting concept, Siemens also developed measures for optimizing ventilation and cooling for the Jelmoli Department Store. As part of the project, 34 ventilation plants were modernized and partially retrofitted with frequency converters. This allowed their volumetric air flow to better adapt to the demand and so reduce power requirements.


The building is cooled by means of “free cooling.” This means that outdoor air is used for cooling as much as possible. The improved building management software also continually records CO2 levels inside the building and reacts if the concentration becomes too high, which ensures high air quality. Thanks to the optimized ratio of outdoor to indoor air, cooling requirements have been significantly reduced.

Picture credits: Siemens Switzerland AG

The “Jelmoli – The House of Brands” department store in Zurich draws customers from throughout Switzerland. Since 2009, Jelmoli AG has belonged to the Swiss Prime Site (SPS) real estate company. SPS AG has a real estate portfolio valued at over 10 billion Swiss Francs. Property management is handled by the real estate service provider Wincasa.


Siemens has been helping SPS to implement self-imposed climate targets since 2012. Siemens engineers screen selected large SPS properties for energy-savings potentials.

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