Illuminating ideas for energy saving

Author : Alastair Ramsay

04 October 2011

The pressure on businesses to reduce energy consumption is at an all time high, and lighting, as the single largest user of electricity in a typical commercial building, is the focus of a great deal of this attention. Alastair Ramsay talks about the role lighting control systems can play in delivering the necessary reductions.

These are interesting times for all organisations. The requirement to reduce energy consumption is coming from all sides, whether through legislation (Part L and CRCEES), environmental schemes (BREEAM and LEED) or the day-to-day pressure to reduce costs, but guidance on how to achieve this in a way that best benefits a business can be confusing.

One thing though is absolutely clear, lighting control systems will quickly prove to be of the utmost importance. Not only do they provide the ability to deliver energy reduction at the kind of levels being demanded, they do so while enhancing the value of pretty much any commercial property.

Just look at the facts. In the UK, lighting accounts for 20 per cent of the annual electricity consumption in non-residential buildings, a figure that equates to 15.2 million tonnes of CO2 at a cost of £3.6billion. Even the most basic of absence detection lighting control installations will, in most cases, save a minimum of 30 per cent of this energy, and therefore cost, by automatically turning off lights when a space is unoccupied.

To save you grabbing for a calculator, this 30 per cent equates to an astonishing annual saving of 4.56 million tonnes of CO2 or £1.08 billion. Looking at the bigger picture, that’s a six per cent reduction in the UK’s electricity consumption in non-residential buildings.

So, what about these systems that look set to deliver so much? Are they expensive? Unfortunately, putting a price on a lighting control system is much like deciding how long a piece of string is. There are so many different variations and so many different types of products available – for example a simple sensor can cost anywhere between £5.50 and £35.50 depending on the quality, sensitivity, cabling method etc – and then there’s installation costs to be taken into account.

Therefore, it’s easier to say that the more sophisticated the system, the greater the initial expenditure, but that this is balanced out by the fact that it will lead to greater energy savings. Perhaps the most important point to bear in mind when looking at the costs of lighting control systems is that in the vast majority of cases the return on investment, in terms of energy saved, is well within two years – with the payback period remaining fairly consistent whatever the system installed.

Many systems also have the added benefit of being easy and rapid to install and commission, whether in a new installation or during the upgrade of an existing one. As an example, the Lightrak lighting control system is modular and operates on a plug and play principle, with many of its components programmed off-site in order to deliver time savings during installation. Its use of KNX protocol ensures compatibility with hundreds of other KNX-certified devices, all of which can be programmed using the same software tool.

The associated buscom trunking was developed specifically to be used in conjunction with Lightrak and other KNX based lighting control systems. Another modular system, the buscom carries power and control communications separately in one casing. It is installed in ceiling voids, with regular tap off points for localised access, which ensures that any future modifications require no cabling changes at all.

What this adds up to is that as well as being easy to install and operate, this type of system is fully future proofed and can be easily upgraded to incorporate new technology. Of course, not every property needs this level of sophistication and so it’s imperative that every installation is properly planned so that it delivers the best and most suitable solution. And to do this, it’s imperative to have a good knowledge of exactly what is available.

There are many different lighting control solutions aimed at a variety of vastly different budgets, many of which can be installed with minimum disruption due to the fact they make use of much of the existing lighting equipment.

At the very simplest level are pure switch operated systems, which enable users to control different lights in different areas, or zones of a room. This approach would, for example, enable lights along a row of windows to be operated independently of the other lights in the same space – a seemingly simple development that can reduce associated electricity use by around 20 per cent.

Further savings can be made by supplementing switches with absence detectors (circa 30 per cent), and even greater ones achieved by using sensors that incorporate ambient light level detection (40 – 50 per cent). These latter sensors will either switch off lights when a specified light level is achieved from daylight or will enable electrical lighting levels to alter so as to retain a consistent level in the space throughout the day while saving energy. Meanwhile, the potential for even more savings (up to 60 per cent) can be made by retaining switches in systems due to the fact individuals will often turn lights on later and off earlier than would be the case if a system was fully automated. This does beg the question why use lighting control systems? The answer of course is that humans are fallible and research shows that lights are more often than not left on longer than necessary.

Despite all the evidence to the contrary, some will still argue that leaving lights on all the time will ensure lamps last longer than ones that are switched on and off regularly. But that is simply not true. A standard rapid start fluorescent lamp left on continuously currently boasts a typical lifespan of 34,000 consecutive hours. In contrast, the same lamp switched on and off regularly at suitable minimum intervals has been shown to have a reduced lifespan of around 30,000 hours, but this is spread out over a longer period of time, meaning from the research the average calendar life of the light actually increases dramatically from 3.9-years of round the clock use to 6.8-years of regular use.

With such huge potential, it’ll come as little surprise that many manufacturers have introduced a host of new components and systems, while drawing attention to existing ones and their benefits, as they jockey to be at the head of the field when it comes to winning lighting control specifications.

Passive Infrared (PIR) sensors detect both presence and absence and are ideal for areas up to 45m2 without obstacles, such as small offices and boardrooms. For areas up to 150m2 with obstacles, such as open plan offices and warehouse facilities, the Ultrasonic sensors are ideal. And dual PIR Ultrasonic sensors are designed for areas up to 90m2 with or without obstacles.

And while all of these sensors may sound complex, they are easily installed and the remote configurators enable them to be quickly and easily programmed and re-programmed without ever having to be removed from ceilings or walls. Wireless switches remove the need to bury cables or run them through conduit due to the use of wiring devices that use radio waves to communicate with the different sensors and lights – a great advantage when upgrading an existing space.

So, with everything seemingly stacked heavily in its favour, and the systems available that will deliver the headline energy savings, the big question is why are more businesses not already reaping the benefits of lighting control systems? The reason, unfortunately, is as straightforward as much of the technology itself. The regulations stipulate the minimum that needs to be done to meet targets and so designers, installers and building owners aren’t incentivised to deliver the best possible solution. Instead the end user has had to be satisfied with what they get rather than what they could have had.

However, everything is beginning to change. With the user facing increasing energy costs at the same time as they are being pressured to reduce energy consumption, and the impact of the Carbon Reduction Commitment Energy Efficiency Scheme (CRCEES) soon to be felt with publication of the first emissions league tables, it seems certain that lighting control systems are about to be given their chance to shine.

● Alastair Ramsay is sustainable development manager for Legrand