The Society of Light and Lighting (SLL) has issued a Position Statement on Circadian Lighting (April 2019). In doing so, it has responded to the many queries from lighting professionals frustrated by the Society’s apparent reticence to discuss an issue that has been a major topic of polite conversation for the past few years. Now that we have a Position Statement we can, perhaps, see the problem that the Society has been having. The world is getting more complicated; and as we learn more we also begin to understand that there is even less that we really know.
Lighting used to be quite simple.
Despite the pleas for Good Design in the introduction to every Lighting Guide, the essence of these documents has always boiled down to a series of numbers; the metrics of how bright (illuminance) and how tight (distribution and glare). This is not to denigrate the efforts of those (far cleverer than me) who produce the Guides, but we all know what ends up in client design briefs – and its not a call for ‘Good Lighting’.
Human Centric Lighting – not
Circadian Lighting is only one factor in this new healthful approach that has been dubbed Human Centric Lighting (HCL) – and let’s get this out of the way straightaway. Every lighting scheme is a ‘human centric’ scheme – even the ones intended for chickens and lettuces, unfortunately. What we have come to mean by HCL is, of course, lighting that has a physiological effect on the body. That is bio-dynamic lighting. And we’re talking about bio-dynamic lighting now because we’ve found a way to link LED technology with the way that the body works (not just human bodies, but chickens and lettuces as well). And here lies the nub of the problem.
We make the wrong assumption if we believe that bio-dynamic lighting works alone. It’s a historical presumption, based on generations of lighting standards built around the ability to perform a task; can I see the gap in that ring? . . .yes, therefore I can do a gap-in-a-ring type of task. The Biophilic world works holistically; you can’t separate lighting from the whole and say that ‘it works’.
The Position Statement concentrates solely on circadian lighting and its impact on the sleep-wake cycle. OK – that’s what circadian lighting is about but concentrating on this single aspect of bio-dynamic lighting leaves an awful lot of design potential undeveloped. The danger in the Statement – the SLL’s red line if you will – is the demand to quantify ‘other intervening factors that we need to understand before we can provide a useful evaluation of the benefits of circadian lighting’.
It is possible – let me go as far to say that it is likely – that biophilic projects will come along where the lighting process doesn’t relate to any current lighting code or standard. But the project will satisfy the requirements of the client – the lighting will work.
This is a new world.
We are leaving a world where we could happily put a scheme in front of a client and be certain that it would work, simply because the numbers have been crunched and everything adds up. We are entering a world where the variables are of such complexity that projects will necessarily be undertaken as a leap of faith. The proof of success will come once the data becomes available, post-occupancy. It’s a dangerous place to be and will require strong nerves from all of those who’ll be expected to put their names to the design schemes.
And that is where the SLL needs to come to the aid of the party. There will be sensible things that we all need to work with and they can be codified; there’s a whole raft of issues in the context of ‘first do no harm’, for example. And that’s before we get to any of the planned-in benefits of the lighting design based on current good practice. Circadian lighting will have a role to play, but I suspect that it’ll be a very small part indeed.
So thanks to SLL for this Position Statement, but now we need to put in some real effort to see what works. And if you, dear reader, know of any projects where bio-dynamic lighting is being used successfully in the UK, please let us know.
