Lighting Density for HVAC Calculation

[Samardas]

Hi,
I was asked by a Mechanical Engineer who designs HVAC as well, what are the approximate lighting watts per square foot that need to be considered for the heat load calculations in a commercial facility. There are conflicting values I am noticing on the internet. I understand it depends on the utilization of a specific floor/area. I also understand it depends on Title-24 tables for specific usage. However, I am looking for an approximate number (maybe a higher number?) related to lighting only. Any thoughts, please? Thank you very much

 

[electrofelon]

Hi,
I was asked by a Mechanical Engineer who designs HVAC as well, what are the approximate lighting watts per square foot that need to be considered for the heat load calculations in a commercial facility. There are conflicting values I am noticing on the internet. I understand it depends on the utilization of a specific floor/area. I also understand it depends on Title-24 tables for specific usage. However, I am looking for an approximate number (maybe a higher number?) related to lighting only. Any thoughts, please? Thank you very much

You could look at table 220.12. in practice those will be higher than actual. I do labs for a client of mine and we light then quite bright and I don't think we've ever been over .83watts/SQ foot, but .625 is more typical.

 

[PD1972]

The lighting power density (LPD) you are supposed to allot for lighting in an NEC 220 calculation is going to be higher than what the code minimums will require as stated above.

Refer to the adopted energy code of your jurisdiction for tables that provide maximum LPD per space type (eg classroom, corridor, copy room) or per building type (eg museum, office, restaurant). That should provide you with the maximum LPD allowable per the energy code and is probably closer to what you'll see. I believe Title-24 should have such tables for your use in subchapter 5.