I am using a high pressure sodium lights for modeling a grow room. I know the energy per space floor area value but couldn't really find values for fraction radiant, visible and return air. Do I need these values to represent the kind of lighting that I am using or just the energy density is enough? And where will I find these values?
Return air fraction is non-zero only if the lamps are recessed into a return air plenum, which they probably are not. Visible fraction (i.e., luminous efficiency) for high pressure sodium lamps is 12-22% according to Wikipedia. Radiant fraction is the remainder.
Just adding for posterity since the Wikipedia article's source is no longer online: Engineering Toolbox has efficacy values (not efficiency). The conversion from efficacy to efficiency is to divide by 683 lm/W
You need to look at Photosynthetically Active Radiation (PAR). See http://agi32.com/blog/2014/12/10/phot...
rpg: oh, I see. Never mind.
PAR is only relevant to the plant growth bit. I believe the OP is merely interested in defining the luminaires correctly with respect to the building energy model, Randolph. Believe it or not, Amir's answer -- complete with Wikipedia reference -- is a better one, given the context.
Even I can't believe it!
Comments
Our first grow-room question? It's about time.