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DES - Online Annual Report 2009

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How much light do people need to shop?

The use of energy in a center is varied. Electricity is mainly needed for ventilation and cooling, to operate conveyors and for lighting. Lighting itself accounts for around 60% of the total energy requirement, making this not only one of the most visible consumers of energy, but the largest one as well.

The goal is therefore to keep the energy requirement in this particular area as low as possible, while still creating optimum lighting conditions for customers and tenants. A team of ECE experts made up of architects and lighting designers has taken up this challenge. Given that individual measures, such as use of the latest lamp technology, are not enough to resolve this complex issue, the team is working on the development of comprehensive new lighting concepts that take into account all relevant aspects, from daylight through to architecture.

The ECE lighting concept: less is more – conscious use of light


One of the main features of lighting concepts is daylight, which is a must in every shopping center. Since individual centers differ from one another in many ways, such as the direction a building faces, every project is examined on its own merits to determine how the use of daylight can be optimised. The question “How much daylight saves energy?” has to be answered afresh every time. Too much natural sunlight increases the need for cooling. The ideal situation is to have diffused light coming in from a northerly direction, since this contributes brightness without heating up the building particularly. A further crucial factor is the design of roof openings. A symmetrical roof made entirely of glass allows a lot of heat from the sun into a center. This can be avoided by having roof sections that are partially closed, for example.

Even in the earliest phase in the planning of each project, an intensive exchange between lighting designers and architects takes place in order to consider the individual energy-related challenges posed by each building. This is where the course is set for the sustainability of the property.

Artificial lighting is “administered in doses” depending on the amount of natural lighting available. Contrary to a popular assumption, the more a building benefits from natural light, the greater the amount of artificial light needed because daylight cannot reach into every corner of the building. If this is not balanced out by artificial lighting, high contrasts are created that visitors find very unpleasant. What is more, the human eye adapts to areas that are brightest, which means that it is then unable to recognise features quite as well in dark zones. That is why it is important to pay special attention, when planning lighting, to the entrance zones where visitors first adjust to the brightness inside a center, to those areas where no daylight penetrates for architectural reasons, as well as to the display windows which should be the brightest zones in a mall.

The right mix of daylight and artificial light

Artificial light ensures that all areas are properly illuminated. To minimise the energy needed to achieve this result, our centers use illuminants that generate very little heat. These mainly consist of fluorescent lamps, which are used in illuminated ceilings and arches, and halogen metal vapour lamps, which are particularly suitable for downlights – small lights usually mounted in the ceiling.

From fluorescent lamps to leds

LEDs, however, are not bright enough for general lighting, and the quality of their colour reproduction is inadequate. They are though used in some of our centers, e.g. in Dresden, Passau and Hameln, for façade lighting, coloured accents and places that are difficult to reach. A further development in the near future will be illuminated ceilings with LED technology. They can be used here to supplement existing arches and downlights, thereby halving the power consumption compared to a traditional fluorescent illuminated ceiling. In addition, lights are switched off where they are not needed during the day. During evening hours, an energy saving of around 50% can be achieved by dimming the illuminated ceilings and arches and turning the ambient lighting down by half. It is with optimisation measures such as these that, within the last eight years, ECE has managed to save 20% of the energy used to illuminate malls while at the same time improving the quality of the lighting.

Less is more - conscious use of light

Brightness levels need to be higher during the day than in the evening. People perceive white light as pleasant during the day, but prefer warm light in the evening.

Use of light

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