Smart lighting control combines sunlight with LED

Aldi Future Store - Rastatt, Germany

Daylight in your shopping basket: The Aldi Future Store in Rastatt, Germany sets new standards with an optimised energy concept.


Category: Retail
Location: Rastatt
Technology: LED luminaires
Year: 2011

Aldi Süd claims the responsible handling of the environment as a fixed part of its corporate philosophy. Together with external experts and scientific institutes the internationally active retail chain repeatedly initiates pilot projects in which it appraises activities for the saving of energy. A particularly impressive result has been achieved with the new Aldi Future Store in Rastatt. The energy concept realised here with the aid of the Fraunhofer Institute for Solar Energy Systems is expected to reduce primary energy needs by 50% compared to a standard retail outlet. The harnessing of daylight and the intelligent control of artificial light have an essential part to play in this.

Responsibility and credibility

After rent and costs for personnel, energy is the third largest position for retail overheads, and according to, Germany's statistics database for the retail trade, companies expect significant cost increases in this area. According to a current survey the energy price in the food sector is today already at 55€/m² of sales floor space. So it's no wonder then that energy efficiency is given high importance with retailers. In addition to pure cost savings, factors of environmental protection also play an important role, as these are decisive themes in the communication with customers. Aldi Süd in this respect depends on responsibility and credibility, and with the new Future Store in Rastatt has optimised all systems towards energy efficiency. Special emphasis was placed on the two largest consumer factors, cold store technology and lighting.

Sales-promoting use of daylight

The new Aldi store achieves significant advantages by harnessing natural light. "We have a total of 28 skylights with dimensions of 2x2 metres and distributed over the complete roof surface," explained the lighting planner Ralph Kensmann from the Essen offices of Illuminance values of 600 to 850 lux are achieved with only natural lighting and according to weather conditions. The ingress of daylight via the rooflights ensures good general brightness in the sales area and thus reduces the need for artificial light. At the same time the visual and design-based attributes of daylight upgrade the space itself. The important connection with the outer world, essential for the feeling of well-being in indoor areas is maintained, and the natural daylight spectrum ensures authentic colour rendering of the goods on offer.

The ingress of daylight needs to be controlled to protect sensitive foodstuffs from the direct entry of sunlight and to avoid heating up and glare in the space. The Siteco micro sun shielding louvre takes on this task. Integrated into the intermediate pane spaces of the rooflights, the lamella louvres allow cool diffuse sky light to penetrate into the interior, while the hot direct sunlight is reflected back outwards. Their position in the intermediate spaces of the insulated window panes protects the specular louvres of ultra-pure aluminium from external factors such as dust and humidity, meaning that they are free of maintenance.

Adding artificial light according to needs

Because of the daylight solution with rooflights, the Future Store has no suspended ceiling. Instead of this, a glimpse upwards reveals the timbered roof supports. These offer solid fixing points for the luminaire trunking. A challenge though was the 5.7 metre distance. No standard trunking system is capable of bridging such gaps without unattractive curves. The lighting designers solved the problem with robust aluminium extruded profile. Siteco Modario® reflectors were installed to these special mounting rails and equipped with 54 W fluorescent lamps.

According to lighting task, various reflector types are attached to the trunking. General lighting is ensured by a Modario® Shop reflector specially modified for Aldi with longitudinal glare elimination. Its fine perforations create a discreet indirect light component to brighten the ceiling surface.

Asymmetric shop reflectors at the peripheries of the retail space ensure that more light reaches the wall surfaces. This asymmetric light distribution makes sure that vertically mounted advertising banners remain highly visible. At the same time the illumination of the walls and ceiling gives a bright, friendly impression to the space. The goods shelving is illuminated with asymmetric distribution shop reflectors. The reflectors guide the light and thus also the attention of shoppers into the vertical spaces of the shelving. Longitudinal glare elimination prevents a view of the lamps and therefore protects from glare.

Wide distribution Modario® aluminium reflectors with CAT louvres ensure ergonomic visual conditions at the cash point areas. In the adjacent packing zones the same luminaire without CAT louvre is used. A lighting management system enables the artificial light to be dimmed according to needs and therefore to be continuously adapted to the level of daylight. Selected goods are emphasised or special accents set with spotlights installed into the Modario® trunking.

Light without heat: cooling shelves and deep-freeze stores

Easily the largest energy consumer in food retail with approximately 65% are the cold stores. Optimisation in this area therefore points to high savings potential. A simple and highly efficient measure is the covering of cooling shelves and deep-freeze stores at night. According to estimates from the NRW energy agency, this enables electricity consumption to be reduced by as much as one third. The agency specifies the relation between light and cooling on its website: "Lamps in the cooling zones have a major disadvantage. About 30% of cooling energy is lost to compensate for the heat given off by the light sources. This is why it is cheaper to mount the lighting units outside of the cooled area." With the Aldi Future Store Rastatt an efficient solution to this problem has been achieved without any compromises in comfort: instead of removing luminaires, the planners have equipped all cold stores with Lumos® LED luminaires from Siteco.

This brings several advantages into the equation. The heat produced by fluorescent lamps does not exist with LEDs, as these produce no heat radiation at the light apertures that thermally load goods that would then have to be cooled down. In addition the innovative Lumos® housing form avoids the loss of cold from the shelving. The stream lined housing of the shelf luminaire integrates itself into the flow circulation of cooling shelves. Thanks to the low power LEDs used, low heat development occurs to the Lumos® luminaire housing, meaning that no additional cooling is required in the shelving.

The LED lighting itself impresses with low power consumption. Compared to fluorescent lamps it needs up to 60% less energy with the same level of brightness, and has a longer service life without maintenance costs. So instead of the frugal illumination of cooling zones, Lumos® offers the right technology to impressively set goods in scene. Special colour temperatures are available for the appetising and stimulating presentation of various product groups.

Functionality, efficiency and convenience

In the 22 cooling shelves of ALDI Süd in Rastatt a total of 88 Lumos® LED luminaires have been installed. Each shelf has one Lumos® head luminaire and three Lumos® shelf luminaires. This configuration guarantees homogeneous illumination of the complete shelf while avoiding reflections, glare and shadowing. The head luminaire floods the upper display with diffuse light and also emits a narrow light beam along the shelf front down to the floor. The three shelf luminaires uniformly brighten the individual shelf units. The deep-freeze stores each have four Lumos® head luminaires. These create optimal visual conditions for viewing from above onto the goods.

The Lumos® luminaires in the cold stores not only display their advantages in terms of energy and quality of light in the Future Store. LEDs are used to illuminate the goods in the cosmetics and bread shelves as well. While the bakery goods are lit with warm white light at 3000 Kelvin, the light for the cosmetics and chemist's articles has 5000 Kelvin, corresponding to the colour temperature of the daylight from the rooflights.

Luminaires from Siteco establish a balance between efficiency and comfort in other areas of the supermarket as well. Monsun® damp-proof luminaires for example have been installed in the storerooms and cloakrooms. Lighting for the parking lots is with Siteco SQ 100 luminaires with convex diffusers. The luminaire heads fixed on 8 metre masts are equipped with 140 W Cosmopolis lamps, and with their special reflector alignments brighten the parking lots with a high level of uniformity at maximum mast distances.

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