8 December 2011
The new standard is the first update since 2002 and contains significant changes to the original. These changes are aimed at encouraging lighting designers and specifiers to consider all of the light sources that are used within the workplace and, to a greater extent, include natural light as well as artificial light. In addition, a greater emphasis has been placed on the use of controls and thinking about lighting the workplace as a whole, rather than on what lux level there is on the work surfaces.
Obviously, as a standard rather than a regulation, the new recommendations are to be seen as ‘best practice’ advice, unless
the brief on a job is to comply
with the latest European standards. However, this latest revision offers specifiers some important guidance on delivering light efficiently,
Where previously the 2002 standard encourages the installation of lighting levels that prepare the workplace for early winter’s evenings, the new standard not only takes into account, but encourages the greater use of daylight and lighting controls in schemes. For retrofits, increased day lighting might not be an option, but with energy efficiency high on the agenda, lighting controls are becoming increasingly important and with this, the new standard encourages the implication of EN 15193: Energy performance of buildings – energy requirements of lighting.
Climbing up the walls
Whereas the 2002 standard concentrated on horizontal illumination, this latest revision has taken on board SLL (Society of Light and Lighting) addendums to LG3 (CIBSE Lighting Guide LG3: The visual environment for display screen use) and LG7 (CIBSE Lighting Guide 7: Lighting for Offices), which stated that there should be 50 per cent of the task illumination on the walls and 30 per cent on the ceiling. By incorporating the requirement for specific levels of illumination on the walls and ceiling, the new standard hopes to put an end to the trend over the past few years of lighting workspaces with swathes of downlights alone, which traditionally provide narrow shafts of light.
Although this approach to lighting moves specifiers a step further away from a product specification model and nearer a design led one, there is still a tendency for people to feel more comfortable with prescriptive calculations. The new standard is an improvement on LG7 in this respect, as the new standard sets a level of 50 lux on the walls for enclosed spaces or 75 lux for offices and education facilities, with a uniformity level, which is far easier to facilitate, similarly on ceilings.
Getting the job done
An interesting addition to the new standard is the move towards activity related lighting. It is no longer necessary to light an area to a uniformity of 70 per cent horizontal illumination throughout the entire space. Thanks to the updated standard, the minimum horizontal illumination in a space can vary between 40 per cent to 70 per cent uniformity, enabling energy savings to be achieved as light levels are reduced in background areas. With this amendment comes the realisation that high, uniform illumination is only vital in key task-based areas and not necessarily in corridors or other general spaces.
The only way is up
Another new introduction to the standard comes in the form of mean ‘cylindrical illuminance’ (measuring vertical illumination through 360 degrees). This encourages designers and specifiers to create schemes that deliver 50 lux on the vertical plane at heights between 1.2 and 1.6m above floor level, within activity areas. By specifying minimum illumination levels for walls and ceilings, it is hoped that this new recommendation will encourage the use of daylight where possible and by default, discourage the use of narrow beam downlights.
Although this all works well in principal, the new standard still has some way to go in terms of encouraging a revolution in workplace lighting design. The 500 lux work surface stipulation that still exists is still an acceptance of the ‘old ways’ of lighting and it will be interesting to see when the next standard review occurs whether this will stand the test of time. As most of us are increasingly working on vertical surfaces in the form of computers, the argument for flooding the horizontal plane with light will become weaker.
With these and many more additions and revisions to the 2002 standard, the creators of EN 12464-1: 2011 are hoping that it will give designers and specifiers the tools they need to provide a better place for people to work, so that performance is enhanced and the light is efficiently delivered to where it is needed, saving energy in the process.
Peter Le Manquais is technical director at WILA
– All light sources, including natural light, are now encouraged and seen as integral
to the design.
– specifiers are encouraged to increase the brightness of a room via ceiling and wall illumination.
levels can now depend on the activities in that space, with high, uniform illumination only vital in
key, task-based areas.
– looks at
the light falling on all sides of a cylinder and averages it. This illuminance brings an emphasis on modelling a scheme so that vertical illumination can be measured through 360 degrees.
– new luminance limits are set for luminaires used with Display Screen equipment (DSE), the description of display screens is according ISO 9214-307.