First, be careful what you categorise under "operating expenses". The devinition used by property managers may be a purely legal one, in other words, what is the residential real estate owner allowed to pass on tothe tenants. The "real" operating expenses as understood in business/microeconomic terms may be differt, tipically more. On the other hand, operating expenses are often only sloppily separated from value-enhancing costs which are "capex", capital expenditures which increase the book value of the building in question.

Second, residential real estate operating costs should not be indicated per housing unit / flat / apartment, but per square meter. In a first step this is the floor space of the building as a whole, also counting "common areas" such as entry hall, floors, bycicle and pram rooms, fitness or party rooms, boiler rooms etc. As all space in a building needs to be operated and maintained in some way, it is only reasonable to distribute the total operating costs of a building to its total space. So you take total operating cost divided by total usable floor area and you get a first indicator, expressed in cost/sqm. In a second indication you divide again the total operating costs and divide them by the residential space in sqm of all housing units / flats / apartments, arriving at total opertings costs per sqm of apartment space.

This is only a brief introduction, ask for more....

What are you trying to achieve with your research in the end?

-Peter Prischl-