Baseline Exterior Lighting Power Allowance

Both methods are accepted for LEED 2009 projects in EAp2. You will show more saving with the old method. The new one would be considered conservative. 2010 better defined the allowance by lighting zone so it was adopted for SSc8 only.

Is it still acceptable to use the 90.1-2007 exterior lighting power allowances for EAp2?  I searched the Addenda database and I still don't find anything mentioning applicability of this Addenda to EAp2/EAc1, yet when we look at the Minimum Energy Performance Calculator v9, the baseline exterior lighting power allowances seem to reflect the ASHRAE 90.1-2010 values instead of 90.1-2007.  I looked through the form update history, and see some mention of changes to the lighting power tables, but no detailed description or backup for those changes.  

Yes you still can use the 2007 allowances. The MEPC was originally created for v4 projects using 90.1-2010. When they created the LEED 2009 using 90.1-2007 version they never changed the exterior lighting calculations. I don't know why.