18,850 sq foot building with 12 units. 120/240v single phase. Cant get three phase. This is the base building with future buildouts to come at later dates. There will be 12 ac units drawing a max of 30 amps each. 12 120v 15 amp electric water heaters and small 120v furnaces. 12 exit lights and 24 em lights. 40 outside soffit cans with 120v 60 watt bulbs. the rest of the building is build out as they are sold. I dont know how to figure the rest of the genaral lighting and recptical load for power company. Is there a standard I should use for not knowing the futrue build outs. The spaces will all be professional type use (doctors, lawyers , office space)

Well, hope this helps as much as I can!

Section 220 for NEC has all the info you need for calculations in the United States
and
Section 8 in the CSA has the info you need for Canadian calculation

I don't know about other areas, but before I start a job of this magnitude, I need approved electrical engineer drawings.

Doesn't the Building Dept have to approve of the electrical drwng/design, before issuing a building permit?

Sugggest you offer a couple of different packages for this shell building. One would install 100 amp panels in each new unit, hook up the known load for that unit, 1 recepticle outlet under the panel, and maybe some lights.
Another package would offer larger panels and more outlets.
See what the owner will pay for and plan accordanly.