Lighting the way 08 June 2012

As plant engineers and facilities managers continue to seek out ways to reduce costs and improve efficiencies, one key area often overlooked could have significant impact. Brian Wall reports on the control and use of lighting

With soaring energy bills and predictions that high energy costs are set to stay, taking an informed and strategic approach to facility lighting and its control is more important than ever. Not only could plant engineers and facilities managers achieve real energy and maintenance cost-savings and help to reduce site CO2 emissions, but they could also improve safety, security and employee comfort on the way.

Engineers and managers should consider the advantages of modern control technologies, as well as new lighting systems themselves, if they want to deliver appropriate lighting in the most energy-efficient manner possible. Quite simply, they're not reaping the full potential of installing efficient lighting systems, if they remain switched on when they're not required.

On top of that, there is the natural versus artificial light issue. "At a fundamental level, those in charge of a building should ask themselves if they are making the most of harvesting and controling access to what is a 'free' commodity – natural daylight," argues Peter Haseler, from Siemens Building Technologies division. "Every time a light is turned on in a building, it generates a cost. By applying a level of automated lighting control technology to the fabric of a building and adopting an intelligence-led approach, plant managers can really begin to maximise use of both natural light [no cost] and artificial light [business cost] to achieve an optimum lighting platform."

Making a plant or building 'think for itself', in conjunction with its natural environment, is the way forward, he insists. "Digital Addressable Lighting Interface (DALI) is the most flexible way of controlling lighting running gear to deliver the precise amount of light constantly to keep people safe and in comfort at all times throughout the day," he says.

So what might be realistic savings? "It is generally accepted that, in a typical building, the total level of electrical energy consumed that can be attributed to lighting is around 28%. So for a typical annual energy bill of £1 million, lighting therefore accounts for some £280,000," says Haseler. Making inroads to cutting that is about multiple approaches. "For example, installing a digital ballast control gear system – such as Siemens' Gamma that complies with the KNX 'open' control system for building controls – ensures that areas are only illuminate when they are occupied," he suggests.

Indeed, taking a holistic approach to lighting controls can generate energy reductions of up to 44%, estimates Haseler. "In money terms, this equates to a £120,000 saving in the energy bill, based on an annual £1 million electrical energy spend, meaning a capital payback period amounting to approximately two years."

Matching activity levels
So how might you start? To achieve optimum energy savings, any lighting system must be matched to activities in the building, observes managing director of Lutterworth Ecolighting, Martin Needham. "In an industrial environment, where there can be fluctuating levels of activity in different areas during the day, this becomes all the more important."

For him, best results are achieved when design teams understand the practical application of the lighting. "This means identifying when lighting is needed, for how long and if there are any areas that require particular attention, such as walkways or workstations," he explains.

That said, traditional sodium lighting or metal halide discharge light fittings typically consume 450—460W, whereas Ecolite fittings can consume anywhere between 76W and 252W, depending on the fitting type, even when at full power. And despite such a low wattage, these devices produce a crisp white light.

"The fittings have built-in sensors to detect motion and monitor ambient daylight levels," adds Needham. "When there is no occupancy in an area, or when there is sufficient ambient daylight, the lights automatically switch off or operate at 10%. We can programme timers so that, when the sensors detect movement, the lights in that zone can remain on for a period lasting any time from 10 seconds up to 72 hours."

Plant engineers examining ways of managing energy use might well want to consider 'open' lighting control systems, low-level presence detection devices and 'eco' lighting devices as part of their energy management focus. With energy costs heading in only one direction, it would seem it's time for some enlightened thinking around lighting.

Brian Wall

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