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    • CommentAuthortony
    • CommentTimeJul 5th 2012
     
    What is best general spec for office lighting into suspended ceiling?

    And what if it was function room for conferences, receptions, dining?
    • CommentAuthorjamesingram
    • CommentTimeJul 5th 2012 edited
     
    high frequency control gear with Tri-phoshor lamps T8/T5 ,
    So 4 x 14W T5 ( 4 x 18W T8) in 600/600 module or LED dimmerable 45W 600/600 modules
    both can have additional emergency lighting backup modules added

    as to function room etc. I'd say plenty of socket to allow for plug in lamps for variable task light
    may be LED wall lights if the bugdet will allow
    • CommentAuthortony
    • CommentTimeJul 5th 2012
     
    Thanks
    • CommentAuthorbarney
    • CommentTimeJul 5th 2012
     
    I would focus on three things:

    1 - what illuminance level do I need, can i meet that task lighting illuminance locally at the desk and avoid a high energy consuming general lighting system meeting that task lighting level everywhere - 500 lux and a cat 2 louvres is widely specified (still) and is a complete disaster from an energy perspective

    2 - i would focus slightly less on the particular lumen package and more on the luminaire LOR - it's no good having a high performing lamp package if most of the light doesn't get out of the box - the metric should be the installed efficacy of the installation

    3 - Daylight linking with dimmable control gear will give huge savings compared to comparisons between different luminaires

    Do all three, and you should be able to show 80% savings over a "typical" office lighting scheme

    Regards

    Barney
    • CommentAuthortony
    • CommentTimeJul 5th 2012
     
    Brilliant thx -- how do I train them to dim the lights?
    •  
      CommentAuthorDamonHD
    • CommentTimeJul 5th 2012
     
    I would like to see more of (3) with possible light piping from outside too: it offers a real saving when the sun is out like having solar PV but at probably a tiny fraction of the cost and space and complexity.

    Rgds

    Damon
  1.  
    Hi,
    I would also make sure the lights are switched in groups. This means if only a small part of the area is being used you don't have to have all the lights on. One office I worked in had this. I sat by the windows and always turned off my patch as I hate the flourescent glow/flicker. When one half of the office was turned over to storerage this half was usually turned off as well.

    Richard
    • CommentAuthorbarney
    • CommentTimeJul 6th 2012
     
    You don't train them to dim the lights - just put the photocells in the right place - conect up to the relevant dimmable ballasts and hey presto - the luminaire modulates to give a constant illuminace level as daylight varies (it also has the davantage of dimming the fittings when new, as the light output will be higher - you effectively save 1/maintenance factor.

    Depending on how far you want to go with controls, I would use manual on with absence off - in small groups as above. If it's a rasonable sized office, you could also consider links to corridor hold etc to avoid lone workers sitting in a small pool of light in a generally dark space

    Good daylight is important for many reasons - let alone the significant energy savings when integrated with the lighting solution - just beware of the need to control glare though - you really don't want to engineer in a "blinds down - lights on" scenario by making the space too "bright" for the users. (Equally, 1 w of solar energy in = 1w of cooling power needed - so the balance has to be the energy saved from daylight compared with the winter heat loss through glazing and the solar gain in summer)

    Regards

    Barney
    • CommentAuthorRobinB
    • CommentTimeJul 6th 2012
     
    Posted By: DamonHDI would like to see more of (3) with possible light piping from outside too: it offers a real saving when the sun is out like having solar PV but at probably a tiny fraction of the cost and space and complexity.


    Does anyone think it realistic to use fibre optic cables to bring daylight into a building? I might be talking rubbish but it would be a nice alternative to those light tunnel things which I also like.
    •  
      CommentAuthorfostertom
    • CommentTimeJul 6th 2012 edited
     
    The cross sectional area of fibre optic would have to be at least as large as the light tunnel - more in fact! Unless light flux was mightily concentrated e.g. by fresnel lens, at the 'skylight' collection surface. It shocked me to discover how lossy fibre optic is, at piping light - I'd thought the whole point was that they were almost loss-less.
    • CommentAuthorbarney
    • CommentTimeJul 6th 2012
     
    Just design the architecture to be able to use simple daylight redirection systems - there are plenty of examples over the last century for spaces such as libraries and galleries.

    It's not difficult - and modern mylar type wavelength attenuated reflective coatings make it even easier

    Optic fibres can work, but as Tom pointed out, you need to concentrate the flux. I did see an experimental unit with 3M's which had a collector plate and a transmitter plate with optic fibre between - experimental and not very successsful - but I guess we could get there. No desire though I suspect - easier to put windows in !!

    Regards

    Barney
    • CommentAuthorRobinB
    • CommentTimeJul 6th 2012
     
    Posted By: fostertomThe cross sectional area of fibre optic would have to be at least as large as the light tunnel - more in fact! Unless light flux was mightily concentrated e.g. by fresnel lens, at the 'skylight' collection surface. It shocked me to discover how lossy fibre optic is, at piping light - I'd thought the whole point was that they were almost loss-less.


    Ah I thought it might not be so simple. Someone on another thread (forget which) was mulling using fibre optics to shift light from a centralised, well cooled LED source and I thought if that would work then the same would go for daylight.

    Could still be very pretty if not very efficient - but then daylight's for free..
    • CommentAuthorbarney
    • CommentTimeJul 6th 2012
     
    It can be done Robin - try a google for Parans solar as one example of a commercial collector and optic fibre transmission system - the internal "effect" is highly influenced by the "luminaire" design at the indoor end of the fibre.

    As I mentioned, 3m's had a working version 20 years ago - but it addressed the problem of poor architecture or constaints imposed by deep plan sites - with better integration of daylight into building design we shouldn't need them.

    Regards

    Barney
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