Reducing lighting costs by 70%
Using sophisticated digital sensors enables lighting to be controlled and dimmed in response to both occupancy and daylight levels.
Modern approaches to lighting control can be installed at the same time as the lighting, and by the same electrician. COLIN LEGG reviews the options available and their benefits.Many household names such as Tesco and Marks & Spencer are already stating their intentions of reducing their carbon footprint. Some are even aiming for carbon neutrality. This has implications not only for renewable energy and modern methods of construction, but also for how to manage energy consumption. In most commercial buildings, lighting accounts for more than half of the electricity used. It therefore makes sense to focus attention on how to provide energy efficient lighting. In addition, Part L2A of the Building Regulations states a requirement for ‘providing lighting systems that are energy efficient’ — yet all of us come across buildings that plainly have only manual lighting control. Ask yourself how many unoccupied offices leave the lights on to waste energy and raise energy bills? Remedy
A simple control system can easily remedy such waste of energy using occupancy sensors that switch lighting on or off via a marshalling box, leading to considerable energy savings. Taking this one step further, occupancy sensors can also incorporate a photocell that switches the lighting off if there is enough natural light. Such systems are not expensive and are installed by electricians. Indeed the labour savings achieved installing such plug-and-play systems more than offset the capital cost of the equipment. Now, however, there is an increasing demand for digital lighting control systems. In part this is because the Building Regulations state: ‘Where it is practical, the aim of lighting control should be to encourage the maximum use of daylight and to avoid the use of unnecessary lighting during times when spaces are unoccupied.’ Digital lighting enables the light output of luminaires to be altered in response to changing light levels. Energy savings of up to 70% are possible using such systems. Over-engineered
In the past, digital lighting-control systems were over-engineered for everyday applications. They were expensive to install and commission and involved a lot of post-installation debugging.
| Plug-in interfaces that distribute both power and data to lighting fittings can be installed by an electrician and make it simple to realise the benefits of digital lighting-control technology. |
Such systems tended to be the preserve of the specialist systems integrator — with a price tag to match. End users could often not fully benefit from such systems because they did not fully understand them. Now that such systems are being used in everyday buildings, not just big corporate headquarters, solutions are simple and can be installed and commissioned by an electrician. They have often evolved from the simple on/off systems that have already been described. Again the hard wiring can be terminated in a marshalling box and several luminaires are simply plugged in. The difference is that the plug-in interface now distributes both power and data to the digital ballasts thanks to the development of new cabling technology. This allows more sophisticated digital occupancy sensors to control and dim the lighting in response to both occupancy and daylight levels. Commissioning can be as simple as programming the sensors using a simple, handheld remote control programmer. Such systems follow daylight patterns very closely and in areas where there is highly variable cloud cover can produce even higher energy savings. After all, commercial buildings are generally occupied in daylight hours. More acceptable
In addition to keeping the accountant happy, research studies show that continuous dimming from digital lighting control is more acceptable to a building’s occupants than manually switched or dimmed systems. Such systems can also respond to changes in light output due to dirt on fixtures and lamps and the depreciation of lamps as they age. Lighting systems are generally over-designed to compensate for such losses in light output, with an initial light output that is typically 15 to 25% higher than at the end of its life. A digital control system can compensate for such over-design and increase energy savings — with research suggesting an additional 5 to 10% energy saving over the life of the lamps. Despite these arguments, some specifiers and/or end users may still desire the flexibility of manual control. With modern systems, there is no need to make a choice between switched or automatic control since it is possible to have the best of both worlds. A conventional wall switch can be hard wired into a marshalling box so that it can override the occupancy sensor if, say, the room needs to be dimmed for a presentation. You can also mix and match technology. Digital lighting control can be installed where it will be of greatest benefit — such as next to windows. In other areas, where there is little or no natural light, occupancy sensors and/or wall switches control the lighting. It appears that the green bandwagon is now unstoppable — it being driven by both corporate social responsibility and legislation. Lighting consumes huge amounts of energy so it makes sense to manage it. Modern digital lighting-control systems can be installed and commissioned by electricians, they are cost effective and they save you money. Isn’t it time you jumped on board the bandwagon? Colin Legg is market manager for Hager’s Klik digital control system.