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Topic Title: Lighting Levels
Topic Summary: 900 Lux for a 'Design Office'?
Created On: 02 February 2009 12:26 PM
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 02 February 2009 12:26 PM
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Joined: 02 December 2005


(I have asked this question in 'General Professional and Technical' but as yet have had no nibbles so I thought I would try in here).

Having been a design engineer for 8 years, I have designed many lighting layouts for offices.

I generally follow CIBSE guides, and/or client specific requirements (MoD has its own JSPs for example, but they mimic whats in CIBSE anyway).

Anyhow, I was out last Wednesday when an external policy auditor visited our office. Apparantly, he claimed that our office is not lit brightly enough, and claimed that design offices should be at 900 Lux average. Our office is around the 550 Lux average mark, and actually gets some minor complaints about it being too bright at present!

Now for the life of me, and from all my previous designs/clients, I have NEVER heard or seen of this '900 Lux' requirement. CIBSE dictates that 'CAD Workstations' be lit to 500 Lux average, and cites this value in numerous publications, not least LG7. I did however find that 'Technical Drawing Offices' (which we are not as we do not have any drawing boards) should be lit to 750 Lux in another CIBSE document (Code for Lighting), but still couldnt find this '900 Lux' requirement anywhere.

My question is; Does anyone know of such a requirement? If so, can you point it out to me?

I am formulating a response to the auditor (who has gave us a non-compliance because of the lighting level!!!!) and would rather not seem stupid should this '900 Lux' actually be correct.

 02 February 2009 12:31 PM
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See my brief reply in GPT

Basically it's a nonsense



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 02 February 2009 12:36 PM
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900 lux does seem quite a lot for a design office! Here in our instrument workshop I have local lighting on the bench to give me about 800 lux at the working plane and that is more than enough for very fine work with small components and screws.
 02 February 2009 12:39 PM
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John Peckham

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As OMS says you might want to ask the auditor for his source reference. I would be happy to have a much lower level of general lighting and user controlled task lighting for individual needs in a design office rather "than one size fits all".

John Peckham

Edited: 02 February 2009 at 12:41 PM by John Peckham
 02 February 2009 12:42 PM
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The person who did the evaluation may have been referring to some building regualtion or building services engineering documents which give the following data on typical values of illuminance;

General Offices, retail shops - 400 lx
Drawing office - 600 lx
Prolonged tasks with small detail - 900 lx

It may be prudent to approach the auditor and source the document they are referencing for their evaluation.


"Take nothing but a picture,
leave nothing but footprints!"
"Oh! The drama of it all."
"You can throw all the philosophy you like at the problem, but at the end of the day it's just basic electrical theory!"
 02 February 2009 07:44 PM
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This subject seems very confusing at times. I have look though some lighting guides which I have and they all seem to mention different illumination levels for activity/location, which some figures have already been mentioned.

Offices: (general) 500 lux with a limiting glare index of 19
Offices: (drawing) 750 lux with a limiting glare index of 16

The above figures have come from a building services handbook for design engineers.

Please also note that approved document L2 requires that non-domestic buildings have reasonably efficient lighting and that they also make use of daylight where appropriate.
 02 February 2009 09:51 PM
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Excessive lighting levels are tiring and prevent the use of computer screens without serious problems. I suggest asking why he thinks this is the right light level for the office. I agree that local task lighting is a much more relaxing and sensible solution in the modern design office or workshop. But then this class often have no idea why they are saying what they inevitably do, often with consequences to the rest of the workforce! I have about 100 lux around my desk, which is great when looking at the computer, and a powerful light when I need to see something else!


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