A changing climate for industrial lighting
May 1st 2007

Paying more attention to the lighting in industrial situations can help to reduce overheads and increase productivity. Keith Huxley of Venture Lighting explains

For some years now, businesses have been faced with growing pressure to reduce prices to meet the expectations of consumers. At the same time, fixed overheads such as energy prices have continued to rise and the 'free for all' on tariffs that followed the opening of the energy markets is well and truly over. Higher energy prices are here to stay and the only way to reduce that overhead is to consume less energy.

One of the major contributors to energy costs in virtually all industrial applications is the lighting – so this is a prime target for improvements.

Factories and warehouses need high lighting levels for health and safety reasons, and the quality of the light also has an impact on productivity. For example, a bright and cheerful atmosphere is good for morale, and lighting that shows colours well (good colour rendering) is vital in many assembly and picking tasks.

So the answer to providing cost-effective lighting is to ensure that these criteria are met in the most efficient way. The light sources, or lamps, need to be efficient and provide a high quality light that ensures high visibility and a comfortable working environment.

In most industrial applications they also need to have a high light output as the light fittings are usually mounted very high, so the light has to travel a long way to reach the working area. This also has a bearing on maintenance costs, as replacing lamps requires specialist access equipment, is time consuming and generates stacks of paperwork under Working at Height regulations. Longer life lamps means less frequent re-lamping and fewer lamps being sent for recycling under the WEEE Directive – all helping to reduce the cost of ownership of the lighting installation.

It also helps if the lighting can be controlled to reduce energy wastage – basically not leaving it on when it's not needed. For instance, if the lighting is linked to photocells it can be dimmed when there is plenty of natural daylight entering the space, thus reducing energy consumption.

The quality of the lighting is also largely determined by the lamp. As noted above, the usual choices for these applications are either metal halide or SON and there are big differences between these. Metal halide lamps deliver a bright white light with high colour rendering which creates a vibrant and cheerful working environment. In contrast, SON lamps tend to have a yellower light which creates a duller environment where colours are not as easy to differentiate.

All of these factors were considerations in the selection of lighting for the new train care facility at Northampton, operated by Siemens Transportation Systems (STS). Here, Venture 400W metal halide light sources in Holophane Prismatron high-bay luminaires have been linked to a sophisticated lighting management system. This enables the lighting to be controlled in zones in relation to occupancy and natural daylight levels.

Thanks to the HID electronic ballast incorporated in Prismatron luminaires, the Venture metal halide lamps can be dimmed in relation to the levels of natural daylight. This means that the required lighting levels are maintained in areas where work is being carried out, making maximum use of the free daylight and minimum use of expensive electricity.

Similarly, in areas that are often unoccupied the lighting can be dimmed when it's not needed and ramped back up when someone enters the space. The fact that the lamps are dimmed rather than switched off means the light comes back immediately without the warm-up time that would be required if they had been switched off.

Seeing in the dark

When lighting external areas such as car parks, metal halide lamps also have another advantage. When light levels are low, the human eye switches from 'daytime mode' – or photopic vision – to 'night time mode' – or scotopic vision. In scotopic mode the eye is more sensitive to light at the blue end of the spectrum, and metal halide lamps give out more blue light than SON. This means that in such areas high visibility can be achieved with lower light levels – saving more energy.

For all of these reasons, metal halide light sources are now the first choice for many industrial applications and can even be retrofitted to existing SON light fittings to provide a cost-effective and 'instant' upgrade to the lighting. As with all lamp types, there is a great deal of variation in quality so for maximum return on investment it's important to opt for high quality, long life lamps from a reputable manufacturer.

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