It should not be calculated with the replacement theory.
First of all, you can always ask in clarifying questions if we are taking into account the commercial usage.
The approach case by case is different:
For example, once you calculate the household cars you can use your personal experience and mention that every 5th car on the street is commercial and divide the households cars number by 80%
For the Malls and hospitals, you need to calculate the commercial vs non-commercial real estate areas and then apply a different number of fo bulbs per sqm