It will depend on the type of industrial use. If it is general light industrial warehouse it would be one set of numbers and the NEC number may be close, if it is a contract pharmaceutical manufacturing facility with class 10,000 clean rooms it would be something substantially higher. Typically any industrial client will have at least a generally idea as to what equipment he is putting in the facility and the load study should start with the proposed equipment list, (There could be one piece of equipment that is an extreme hog of an electrical user that would not be accounted for in a per square foot calculation) then a square foot Volt amp factors from NEC or other source could be added on for ancillary electrical users (ie convenience outlets, lighting, etc)