2008-05-07
Our Voltimum Experts answer your questions on a daily basis in our Technical Expertise area. This first Question of the Day, concerning luminaires and lux levels for general office lighting, is answered by Thorn:
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| Office lighting by Thorn - Gateshead Civic Centre |
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Question: I am specifying a new office in Tamworth for Severn Trent Systems.Part of this is open plan drawing office, administration, contract projects conference rooms management suite etc.
Lighting is not my field, and I can't get anyone to help on this issue. The office is to be leased from a developer who has M+E consultants who don't seem to have the answer I seek. The tender is to be let shortly and I have an opportunity to influence an alternative light fitting.
The specification is for design build, and the specification for the lighting says that maintained luminance shall be 400lux in office areas. The cleaning intervals must be two years for luminaires, plus a four-year lamp replacement cycle, assuming 225 hours use/annum.
The STS manangement team has seen a similar office on site to the same specification and considers the lighting to be dim, and not good enough. I am told that 400lux is normal lighting standard for this type of office and that it must be down to the type of lighting fitting, which seems to be a shaped diffuser type. But, I get the impression that it has been left to the contractor to design this and price may have a bigger persuasion than technical merit.
Can you assist in telling me whether 400lux an acceptable lighting level for this situation? Also, what is the best type of fitting to achieve the optimum light for an open plan office environment? I am told that lighting fittings have changed to diffuse light so that computer screens are more easily seen and this might affect the situation. Is this so? Is it possible measure to ensure that 400lux has been achieved? Finally, how big an effect does ceiling and other colour have on lighting level achieved, assuming the use in this application of light pastel coloured walls and ceilings.
Answer: There are a few things to address here, the first being the lux level. Generally speaking, 500lux is the amount required for the general office environment - however you mention a drawing office which may require more (CIBSE recommendations is 750lux for drawing boards specifically). Bare in mind, though, that these are simply recommendations and it is always up to the contractor/specifier what they have. Thorn has a wide range of luminiares specifically designed for general office use. These vary in appearance and price. Some are standard three- or four-lamp Cat-2 fittings (Cat-2 would be the standard referring to the angle of light hitting computer monitors, ensuring that it is comfortable for people to use their computers without worrying about glare), to fittings that are designed to help an installation comply with LG3 and LG7. These are two lighting regulations are designed to ensure that an office installation doesn't have dark ceilings, dark walls/corners - basically making sure that there is a comfortable light level at every corner of the room. These categories are common and are often required by local councils for any new-builds.
Light can be measured with a standard light metre (available from a wholesaler).
Lastly, ceilings, walls, desks, carpets, everything can have an effect on light levels. There are many factors to address when designing a lighting scheme for an office (or any installation) - reflectance, colour, windows, glare etc. But these will be calculated if/when a lighting designer designs a scheme for you.
You can see our full range of luminaires on our website at www.thornlighting.co.uk. Alternatively, ring Thorn Technical directly on 0870 600 8111. We can also assist with contacting a Sales Engineer in your area who can help you chose the fitting that meets your requirements and also do a lighting design plot for you to ensure you get exactly the correct amount of fittings to meet your required lux levels.
To see many more Q & A in Voltimum UK's Experts Area, please click on the link:
http://www.voltimum.co.uk/consult.php?universe=consult.index.questions
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Related contacts
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Thorn Lighting
Silver Screen, Screen 2,
Elstree Way, Borehamwood,
Hertfordshire WD6 1FE
Tel: 0208 732 9800
Fax: 0208 732 9801
Email: brochures@thornlight.com
Web: www.thornlighting.co.uk |
Thorn Lighting
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Source: Thorn Lighting & James Hunt |
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