Lighting Watts per Sqft. Office greater than 10,000 sf

[strap89]

So where I'm at, the energy code requires that offices have a lighting power density of 0.8 watts or less when using a full building square footage calculation. With LED lighting, I'm actually seeing levels of about 0.6 to 0.7 watts per square foot when I target 50 fc in most of the office spaces. 0.6 watts per square foot seems low. Just curious where other people who have familiarity with LED lighting typically come in with their lighting power densities.

 

[Ingenieur]

So where I'm at, the energy code requires that offices have a lighting power density of 0.8 watts or less when using a full building square footage calculation. With LED lighting, I'm actually seeing levels of about 0.6 to 0.7 watts per square foot when I target 50 fc in most of the office spaces. 0.6 watts per square foot seems low. Just curious where other people who have familiarity with LED lighting typically come in with their lighting power densities.

is the 0.8 based on leds? probably not
seems about right imo
non-led office, 8' clg, 30" work surface, 40 fc ~ 1 w
I would expect the leds to be around
50/40 x 0.4(led 2.5 more lumens/watt) x 1 = 0.5 w/sqft
depends on diffuser, reflectivities, etc

there are a couple of lighting experts around, hopefully they will pop in

 

[strap89]

is the 0.8 based on leds? probably not
seems about right imo
non-led office, 8' clg, 30" work surface, 40 fc ~ 1 w
I would expect the leds to be around
50/40 x 0.4(led 2.5 more lumens/watt) x 1 = 0.5 w/sqft
depends on diffuser, reflectivities, etc

there are a couple of lighting experts around, hopefully they will pop in

Thanks for the reply Ingenieur. 0.8 is the maximum watts per square foot allowed by the Florida Energy Code when using the full building calculation method. You are allowed to go 1.0 watts per square foot with the space by space method. You can use flourcent or LED, as long as you are below this threshold. I recently just did a design that came in at 0.6 watts per square foot. Most of the space was designed at 50 fc except for the corridors and support spaces.