I was just wondering if anyone knows the W/sqFT value for a 4ft fluorescent light. If there's multiple is there a scale to use or is it just linear because there will be 40x 4ft lights in the building I'm modeling.
Detailed answer: A "4ft fluorescent light" as described could draw a
wide range of input watts. If you need to arrive at the answer without
the lighting installer/specifier handy, you must figure out the input
watts per ballast. If you can't read a make/model from an actual
installation, first identify the type and quantity of lamps per fixture
(i.e. 4-32WT8, 2-54WT5HO, 1-28WT8). Identify any other specs including
specified ballast factor, power factor, whether it's dimming, etc.
Armed with that info (or a make/model), turn to catalog data to
determine the input watts. Advance has a relatively handy lookup tool
online I'd recommend where you can generate a representative cut sheet
based on known properties. Phillips, Sylvania and I'm sure others make
good ballast catalogs in print as well.
Input Watts/ballast * Ballasts per fixture * Fixture Quantity / Building
Area = Watts per square foot
The total is "linear" in the sense that there aren't any diversity
factors involved in installed LPD calcs... at least in a context typical
for this mailing list (energy modeling / 90.1 / LEED / etc).
If you're asking about electrical service calcs (NEC), this is probably
the wrong forum (I'd suggest searching/asking within
http://forums.mikeholt.com/).
Hi Derek!
Short answer - ask the lighting designer ;).
Detailed answer: A "4ft fluorescent light" as described could draw a
wide range of input watts. If you need to arrive at the answer without
the lighting installer/specifier handy, you must figure out the input
watts per ballast. If you can't read a make/model from an actual
installation, first identify the type and quantity of lamps per fixture
(i.e. 4-32WT8, 2-54WT5HO, 1-28WT8). Identify any other specs including
specified ballast factor, power factor, whether it's dimming, etc.
Armed with that info (or a make/model), turn to catalog data to
determine the input watts. Advance has a relatively handy lookup tool
online I'd recommend where you can generate a representative cut sheet
based on known properties. Phillips, Sylvania and I'm sure others make
good ballast catalogs in print as well.
Input Watts/ballast * Ballasts per fixture * Fixture Quantity / Building
Area = Watts per square foot
The total is "linear" in the sense that there aren't any diversity
factors involved in installed LPD calcs... at least in a context typical
for this mailing list (energy modeling / 90.1 / LEED / etc).
If you're asking about electrical service calcs (NEC), this is probably
the wrong forum (I'd suggest searching/asking within
http://forums.mikeholt.com/).
~Nick
NICK CATON, E.I.T.