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NC-2009 SSc8:Light Pollution Reduction

Interior Ligting - definition of the direct line of sigth

We are working on a building including offices and a warehouse. For the warehouse, there is a night time operation assumed. For the interior lighting, the credit requirement / Option 1 states 'reduce by 50% the input power to interior luminaires with direct line of sight to envelope openings'. I would like to clarify how the direct line of sigth is defined - is it related as a) to the actual light source (i.e. bulb) within the luminaire, or b) to the whole luminaire? If a) is correct, would that be enough to specify downligth luminaires not allowing any direct view of the light source (bulb) from the exterior? I understand that reflected light would still be visible outside, but guess the intensity would be several orders of magnitude lower. Or is b) correct, in which case the use of downligth luminaires would make no difference? Thank you for any thoughts on this

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Fri, 08/03/2018 - 09:49

Hi, I am also working on a factory that consist of office, warehouse, and production zone. Envelope around the warehouse and production are only opaque wall. But for office zone, there are some glass on envelope around office zone. In this case, could I consider lighting in office zone as "interior lighting with direct line of sight to envelope openings" and consider lighting in warehouse and production zone as "non-interior lighting with direct line of sight to envelope openings". If yes, I would not include the interior lighting in warehouse and production zone in calculation of 50% input power reduction.
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Bill Swanson
Sr. Electrical Engineer
Integrated Design Solutions
LEEDuser Expert
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Mon, 08/06/2018 - 12:26

Regarding the original post.  There is no specific definition to direct line of sight.  I side more with the light source as you described it in (a).  But if a lens or some transparent part of the fixture is visible I will follow (b). To the recent post.  If the warehouse and production zone only have opaque walls, I would consider it as "interior lighting without a direct line of sight to envelope openings."  Since there is no direct line of sight thru an envelope opening it does not require the lighting to be reduced by 50%.  Since the office area has windows, the 50% rule would apply to any lights visible from outside.

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