I see a total of 2400 sq ft. 4 renters are using 1400 sq ft, that I assume is space that is "exclusive to the renters" and not shared with non-renters. That's 58% of the floor space.
You don't say how many total live in the house. But if I assume the owner and their spouse/partner, that gives a total of 6 people with four of them renters. So that would be about 16.6% per person with 67% of the utilities used by the four renters.
Keep in mind the choices only apply to utilities. It does not apply for other things such as depreciation. Depreciation is based on sq ft that is exclusive to the tenants, regardless of the number of tenants. So you should be depreciating 58% of your structure cost basis over 27.5 years. Likewise, the percentage of your deductible mortgage interest is also based on percentage of sq ft exclusive to the tenants.
