A lot really depends on the use of the space, and what the lighting is. Most of that can be done by VA/sq'. See 220.3(A) through (C), 220.10 through 12 may also be applicable, and there is an example in Annex D-3.
This is a portion of the FPN on 220.10
See 220.4(B) for the maximum load in amperes permitted for lighting units operating at less than 100 percent power factor.
Happy number crunching....