How dangerous is BS EN 12464-1:2021 for Good Lighting?

Here at The Light Review we’ve had to reach for the dictionary to check on the meaning of the word ‘dichotomy’ – because I suspect that we’ve got one.

DICHOTOMY (noun): a division or contrast between two things that are represented as being opposed or entirely different.

The lighting industry has spent many years waging a still-ongoing struggle to reduce the energy demand created by our technology. And we’ve done very well at it, I think we can all agree.
Pat on the back.

More recently, though, we’ve been investigating the healthfulness of that lighting in the built environment. You know all about that thing we decided to call Human Centric Lighting (HCL) by now, so I don’t need to repeat what that’s all about. But what’s come out of that exploration looks for all the world like a need to increase illumination levels (and to be honest, I’m concentrating on offices here).

So-o-o-o-o-o: while a climate emergency is calling for even greater reductions in energy spends in our buildings – and we’re well set to accomplish something there, we’re now also obliged to consider increased lighting levels on the grounds of health and wellness.

Houston: we have a dichotomy . . . and probably a moral dilemma.

This autumn sees the publication of the latest version of BS EN 12464-1:2021 Light and Lighting of Indoor Work Places. Not to put too fine a point on it, it’s recommending that we need a lot more light. Meanwhile, that old simple equation that More Lux = More Watts and More Watts = More Cost still stands.

Looking at the proposed  methodology given in the new Standard, not much has changed from previous editions, but it’s the numbers that we need to look at. And we really need to take an honest look at how most office lighting schemes are produced.


Despite a detailed set of metrics that describe relative illuminance levels for task areas, the area immediately surrounding the task, and the perimeter spaces, we KNOW that only one simple figure matters. From SLL LG7, that figure is 300Lux, and it’s become the benchmark illuminance level for lighting the entire space, NOT just for the task. No one bothers to read the rest of the Guidance. And thus it will be with this new Standard and it’s Lux-on-steroids recommendations.


The latest edition (BS EN 12464-1: 2021) has gone a long way beyond 300 Lux, and has added two further modifying steps that permit far higher illuminance figures.

  1. The REQUIRED task illuminance level now starts at 500 Lux.
  2. Task illuminance can be MODIFIED in certain circumstances, typically, because of the age of the occupants of the space. That 500 Lux figure can be lifted to 750Lux, or – if the situation is more acute, to 1000Lux (its this incredible figure that has started alarm bells ringing across the land)

(an aside: way back in the 1970s, The Electricity Council – of blessed memory – issued its own guidance on lighting levels and 1000Lux was the go-to figure for office lighting. Why? Because the Electricity Council was SELLING ELECTRICITY. After the oil crisis of 1973, office lighting levels dropped to 500 Lux – no one noticed, no one complained, and life went on its slightly less brilliant way.)

The usual justification for 300Lux across the entire space.

Despite the diagrams that define and differentiate between task – surrounding – peripheral areas, it’s the 300 Lux task figure that scheme designers buttoned onto; mainly because it’s always been easier for office lighting to be based on an overall field covering the entire space (kowtowing to the English predilection of not being arsed to work out anything as useful as a furniture layout beforehand). We’ve always tried to keep the numbers as simple as possible in this country.

I have two major concerns;

Picture this:

A new office is to be lit under the aegis of BS EN 12464-1:2021. The lighting rep asks the fit-out contractor what’s going on. “Who knows” comes the bold reply. “The usual stuff, I suppose”.

“Well”, says the lighting rep, “we’ve got new standards that need to be applied. And, believe it or not, lighting levels are based on the age of the occupants – yes, I know. Crazy. I suppose we’re looking at the typical age spread, with a few oldsters asleep in the corners? So it probably ought to be the full 1000 Lux . . . but I’m sure I can work up an argument that’ll gives you 750Lux – and a 25% saving.
What do you think? Of course, it’s a pity that you can’t tell us where the desks are going. We’ll just have to go for the usual blanket lighting. Then you know you’re covered.”

And that’ll be the coup de grace for many a lighting scheme.

Or how about this one:

A new office is to be lit under the aegis of BS EN 12464-1:2021. The lighting rep asks the fit-out contractor what’s going on. “Who knows” comes the bold reply. “The usual stuff, I suppose”.

“Well”, says the lighting rep, “We’ve got some crazy new standards that we need to abide by, but I reckon that we can save you some decent money on the CAPEX budget. You see, we now have to separate out the actual desk lighting from the room lighting. And if we don’t know anything about where the desks are going – which you don’t – then all we need to light is the basic room lighting. That’s what they call the ‘peripheral illumination’, and I reckon that we can satisfy the new Standards by providing 200 Lux. And that’ll be a one-third saving over what we’ve all been doing up to now.”

“You don’t need to worry about the desk lighting – just leave that to the fit-out guys.”

Potentially, this is a Standard to print money for suppliers, safe in the knowledge that the only thing that will interest the contractor will be the two things they’ve heard of; light levels (Lux) and glare (UGR).

And if you want anything more complicated you’ll need to employ one of those expensive lighting design companies, who’ll only spend even more of your money. Just leave it to us.”

Why are we in this situation?

It’s because of the Great Pyramid of Lighting Design.

This is a graphic representation of where lighting design comes from, by volume. That golden cap is the exemplary stuff that comes from the kind of people who write Lighting Guides and Standards. They’re also the kind of people who don’t need Guides and Standards.

As we slide down the slope of the pyramid the layers get darker and heavier as we head for goblin territory; to the people who really, really, need to read the Guides and Standards . . . and who never will. But they will clap onto a couple of numbers, like 1000Lux and UGR19. “Yeah – we can do that for you.

In conclusion:

I have a horrible feeling that this new Standard is a potential disaster for both energy management and the (laudable) healthful aims that it aspires to.

Why so?

Because the wrong people are controlling the majority of lighting specifications. There’s nothing new here; it’s been like this for decades. If we’re serious about Workplace Lighting then it’s time we took steps to ensure that those producing it are properly competent and that those asking for Workplace Lighting understand their responsibilities to achieve the desired ends that balance energy usage and a healthful environment.


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