[Bldg-sim] question regarding lighting efficiency/gains units ofmeasurement

[Jill Dalglish]

Since the conversion of fc to lux is the same conversion of ft^2 to m^2 
(by definition), 1 W/m^2/lux = 1 W/ft^2/fc  Not messy at all!

The US codes don't usually combine luminaire horizontal work plane 
efficiency (lux/W or fc/W) with LPD (W/ft^2 or W/m^2).

*Jill Dalglish, PE, LEED AP BD+C*

Dalglish Daylighting
S/W/DBE Certified Business
_www.dalglishdaylighting.com_ <http://www.dalglishdaylighting.com/>




On 5/29/2014 11:18, Guglielmetti, Robert wrote:
> On 5/29/14, 10:53 AM, "Nick Caton" <ncaton at smithboucher.com<mailto:ncaton at smithboucher.com>> wrote:
>
> To date, I have not yet encountered a "W/ft^2 per 10fc" requirement.  Our lighting power densities are typically prescribed more simply per space type or per building/project type to establish a ceiling for maximum installed lighting (for example: Offices are 0.9 W/ft^2, Parking Garages are 0.25W/ft^2).  The actual figures prescribed of course vary quite a bit depending on where you are and what energy standards/codes are being enforced (if any).
>
>
> Yup. To be fair, ASHRAE goes through a rigorous process of validating the LPDs against current lighting technology (enlisting lighting experts from PNNL), ensuring the proposed LPDs can actually produce reasonable illumination levels. However, this assumes some lighting design is actually happening during these retrofit exercises. You know the old saying about assuming?
>
> - Rob
>

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.onebuilding.org/pipermail/bldg-sim-onebuilding.org/attachments/20140529/96e91ef2/attachment.htm>