LIGHTING SPECIAL SLL CODE
SLL CODE: KEY CHANGES
Lighting requirements l Each task now has its own uniformity requirement
l There is now a requirement for a background illuminance
l There is a requirement for illuminance on the walls and ceiling, although the levels are below that recommended by the SLL
As Raynham points out, not only is the
intention to promote good practice over and above the standard, but also the SLL is very involved in pushing for the standards in the first place. The latest edition, however, is not just
an update of the 2009 version, according to Raynham. ‘This time it’s a real rethink. Basically we took what we had, tore it up and started again.’ Because it reflects the changes to BS EN 12464-1, it now introduces mean cylindrical illuminance values and shifts the emphasis to lighting for the specific task (see the Journal, September 2011, page 34). ‘The most radical change is the
requirement for cylindrical illuminance in offices and buildings in general,’ says Raynham. ‘Classically we would talk purely about
lighting visual tasks and now we’ve realised that we have to look at people in offices. We
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have what I guess is probably a finger in the wind value and we will know in five years’ time whether it’s a good value to use or not. At least introducing it is a start. ‘The place where it’s most important,
and where it will have its biggest impact, is probably schools, where you have to have good communications between the teachers and the pupils. Secondly, meeting rooms and offices and those sorts of spaces.’ There are two drivers for rethinking the
working space: lighting quality (lighting for people) and energy efficiency. While the phrase ‘working plane’ has not been mentioned in a Code since 1994, the preoccupation with throwing a blanket of 500 lux over a space persists, despite the fact that it is wasteful and pointless. Raynham hopes the new direction will finally, if slowly, put paid to it. ‘The other thing that we’ve emphasised,
l There is a requirement to provide a certain amount of semi-cylindrical illuminance in all spaces to make it possible for people to see each other’s faces
Content and appearanCe The new revised edition of the SLL Code for Lighting is significantly different to previous editions, both in content and in format. The Code in book form will now have a similar format to the SLL Lighting Handbook, which now covers some material traditionally covered by the Code – all the old material relating to lighting equipment and lighting design, for example – so that the two together will become the definitive lighting reference.
December 2011 CIBSE Journal 47
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