Taking control for better lighting
LED lighting is highly efficient, but it will still benefit from good control technology to support long-term operational efficiency, as Richard Holt of Trilux Lighting explains.
The switch to LED technology for lighting has been widespread across a range of building types from offices to schools and retail. Users have found LEDs offer high-quality, flexible and robust lighting solutions that meet a range of requirements.
The move to LEDs has been very much driven by the requirement to reduce energy use in buildings. The importance of considering energy efficiency in relation to lighting is highlighted by the CIBSE Lighting Guide, which states: ‘The objective of any lighting installation is to meet all of the lighting needs of the people using the area being lit, whilst consuming a minimum of energy.’
Although moving to LED lighting can result in savings of itself, it is equally important to think about lighting control, because this impacts both on long-term energy use and occupant comfort.
There are, of course, ways to reduce the amount of light needed in a space at the outset of a project, thereby cutting long-term energy use. Calculating the correct maintenance factor (MF) is crucial, for example, so that lighting is not over-specified to compensate for falling lux levels over time. The right MF means less capital expenditure and better value for money for the client.
However, simply reducing the amount of light to save money is not the correct approach. As the CIBSE Lighting Guide comments: ‘Any attempt to save energy by skimping on the lighting is doomed to failure if a space is poorly lit. In such a situation, people using the space are likely to perform less well and thus the productivity of the whole space is compromised; this reduces the effectiveness of the space.’
Although getting the amount lighting correct from the start is important, controls offer significant benefits in the long-term. Firstly, modern lighting controls support better planning, installation and commissioning of lighting systems. This seems like a big claim, but the latest technologies are making the work of engineers and installers easier.
For example, LiveLink from Trilux offers preconfigured settings for common scenarios. This means that for typical lighting situations, such as corridors, classrooms or offices, luminaires and sensors are grouped according to requirements — and pre-programmed with the correct parameters. Commissioning is made easier with apps that use touchscreen commands to guide users through the installation and commissioning process.
Perhaps the most important, and often overlooked, aspect of lighting controls is how occupants in the space will interact with them. As the CIBSE Guide says: ‘It is often the best solution to provide some sort of automatic control system to ensure light is only provided when necessary. However, care is needed to ensure such systems are accepted by the users of the lit space.’
One of the most important strategies lighting controls can achieve is that lights are switched off when they are not required. Lighting control can support this with a simple 'auto-off' function that ensures lights are not accidentally left on in meeting rooms, for example. Another approach is to use occupancy sensors to turn lights off when not required.
There have been some interesting developments in this area recently. Occupants can find it irritating that office lights switch off if they are sitting still at a desk typing, for example, so they have to intermittently wave their arms at the sensors to keep the lights on.
The LiveLink system uses highly responsive sensors from Steinel which can pick up on tiny movements, including hands on a keyboard. This means that lights switch off when not required, but remain on when needed by occupants.
Another energy-saving approach that good lighting control supports is the use of daylighting when it is available. Not only do occupants benefit from natural light, this control strategy can save significant amounts of energy. Again, the latest controls respond to daylight levels, with brightness adjusting across the day to ensure that artificial light is only used to achieve the brightness levels required.
Ultimately, lighting controls provide a way for occupants to interact with the lighting and to achieve the lighting they want in a space. The 'controllability' of equipment is addressed in the CIBSE guide, which points out that unless an interface is easy to understand, it won't help occupants be comfortable or support energy efficiency.
The days when users were faced with unfathomable banks of lighting switches should be gone. With the advent of smart phones and touch-screens, it is possible to specify control systems that give users control of their space through a familiar medium such as their phone or tablet.
Overall then, LEDs by themselves can save energy, but they can save much more if controls are also considered as a vital part of the lighting system. This leads to spaces which are more energy efficient and better to be in.
Richard Holt is managing director of Trilux Lighting.