Question-and-Answer Resource for the Building Energy Modeling Community
Get s tarted with the Help page
Ask Your Question
1

high pressure sodium lights fraction radiant, visible, return air values?

asked 2016-07-31 16:32:00 -0500

siddharthpatil5 gravatar image

updated 2016-07-31 16:46:17 -0500

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?

edit retag flag offensive close merge delete

Comments

Our first grow-room question? It's about time.

__AmirRoth__ gravatar image __AmirRoth__  ( 2016-07-31 16:47:09 -0500 )edit

2 Answers

Sort by ยป oldest newest most voted
3

answered 2016-07-31 16:54:38 -0500

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.

edit flag offensive delete link more

Comments

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

matt gravatar image matt  ( 2021-07-21 12:37:41 -0500 )edit
1

answered 2016-08-02 11:24:09 -0500

updated 2016-08-02 15:56:10 -0500

You need to look at Photosynthetically Active Radiation (PAR). See http://agi32.com/blog/2014/12/10/phot...

rpg: oh, I see. Never mind.

edit flag offensive delete link more

Comments

1

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.

rpg777 gravatar image rpg777  ( 2016-08-02 11:46:43 -0500 )edit

Even I can't believe it!

__AmirRoth__ gravatar image __AmirRoth__  ( 2016-08-02 16:44:01 -0500 )edit

Your Answer

Please start posting anonymously - your entry will be published after you log in or create a new account.

Add Answer

 

Question Tools

1 follower

Stats

Asked: 2016-07-31 16:32:00 -0500

Seen: 142 times

Last updated: Aug 02 '16