Richard Hayward, lead marketing manager for Legrand’s wiring devices business, discusses the current state of affairs in the LED market, and how a new set of standards could pave the way for greater efficiency across both new build and – crucially – retrofit applications:
LEDs are now firmly established as the first choice for the specification of new-build lighting applications in both commercial buildings and domestic dwellings.
Yet, whilst they can reduce energy bills, minimise maintenance and dramatically cut a building’s carbon footprint, confusion still remains surrounding retrofit applications – particularly regarding the best way to integrate either replacement lamps or ‘dimming technology’ into existing wiring schemes and control programs.
In the past, the emphasis on LEDs’ energy efficiency has overshadowed the focus on design and aesthetics. However, the past 12 months has witnessed noticeable improvements, particularly regarding the quality of LED colour rendition, meaning dimming and LEDs now offer both a cosmetic and energy efficient solution.
Quality counts
One of the biggest misconceptions about LEDs is that they cannot be dimmed to zero: this is simply not true. Or, rather, it’s not always true. The dimming capability of an LED depends on the LED unit and, while most will not dim to zero, some will.
As with most elements of lighting design, there is a price premium attached to a higher quality product and for most applications, dimming to zero is not required – after all, if the light needs to be dimmed to zero, an off button might be the most useful approach.
In fact, the dimming range for LEDs varies from unit to unit and it's essential that specifiers not only define the dimming range they need when designing a lighting scheme but also that they select a product that can meet that criteria. From there, it’s a matter of working with a wiring accessories specialist that can meet their needs with dimmer drivers that will offer dimming functionality within the tailored range required.
Dimmer drivers for LED lighting
Legrand has developed LED dimmer drivers for both the Arteor and Vantage building automation systems and also offers Radio/ZigBee LED compatible dimmers and Arteor wiring accessories with integral LED compatible dimmers.
The dimmer driver can be set to meet the dimming parameters required by the lighting designer – provided the chosen LED unit is compatible with those requirements – so, for example, the dimmer driver might provide dimming down to 30% of the fitting’s lighting capability. Individual dimming profiles can be set for each lighting unit to enhance flexibility and design choices, so, for example, a dimmer switch that controls four loads may be set to provide a different dimming range for each one.
This flexibility is great news for consumers because it means that dimmable LED lighting is available to all, not just for homes and offices that have building automation systems. It’s also great news for lighting designers as it means that LED-based schemes can match the aesthetics and functionality of conventional lighting.
Extra energy savings
The benefits of LED dimming are not purely aesthetic, however. Like most artificial light sources, LEDs lose some of their performance over time, as is the case with fluorescent light sources, for example. If they are used at full capacity from day one of installation, this means that the brightness they produce will be substantially reduced by the time they reach the last third of their service life. At that point, the lumen levels provided may not be sufficient for an adequate working or ambient light for the space if this is not taken into consideration at the design stage.
In a domestic setting where the required lumens level is not as critical and where there are only a small number of fittings, this may not be a major issue. In a commercial setting, however, reduced light output from multiple light sources is a maintenance issue that can be avoided with dimming technology.
The answer is to implement a constant illuminance system where the maximum amount of artificial light provided by the LEDs is limited to the maintained level required for each area. So, for example, an office may need 70% of the LED units’ lighting capacity as its maximum requirement so the dimming range profile might be set at 10-70% and the lights would operate at 70% capacity when undimmed.
Where this is implemented, the building not only saves 30% of the energy required to power the LEDs but the occupier or facilities manager has the flexibility to pre-set the dimming range as the units age and their lighting output becomes compromised, maintaining constant illuminance by using the spare capacity in the LED. This maximises the service life of the unit and reduces the maintenance burden.
Collaborative development
In short, dimming for LEDs is perfectly possible (either as part of a lighting control system or as a conventional lighting installation) - it just requires an LED-specific approach which so far has been difficult to measure, largely because of the lack of international standards on dimming compatibility.
However, good news is around the corner. The development of a new set of European standards will enable manufacturers to ensure that all dimming products, which enter the marketplace – both for new build and retrofit applications – can be measured against a consistent benchmark; something that so far has been lacking.
The European standardisation organisation, CEN, is in the process of developing a new set of standards following the formation of a joint working group between those involved in controls (such as dimmers) and lamps. Through the partnership and subsequent legislation, the industry should – it is hoped - demystify the misconceptions about the difficulty of dimming LEDs that are integrated into the lighting design.
Whilst the new standards will not have an effect for a couple of years, it is reassuring that CEN is committed to resolving any outstanding compatibility issues between lighting controls and LED lighting.
LEDs are here to stay and it’s high time the industry makes the effort to completely understand their potential in order to maximise overall lighting system efficiency and collectively cut out unnecessary carbon consumption.