ASHRAE 90.1 control requirements


Senior Member
New England
I'm reading through section 9 of ASHRAE 90.1-2010 and it has some peculiar requirements I've never seen before. requires all spaces to have at least one control step between 30 & 70% of full light power. I've never designed to this, nor seen it in other's designs.

9.4.1 requires all automatic-on lights to turn on to not more than 50% of light power (with a couple of exceptions). Again, this is not something I've ever seen. All the occupancy sensors I've seen are full on or off.

I also don't see an allowance for lights on 24/7 but any store I drive by has lights on inside and in the lobby that never turn off. What gives?

Am I missing a common exception? I've never seen a space designed to these requirements. Thanks for insight!