How to divide my AC bill with my tenant?

[Kumar Gaurav]

Hello,

I own a duplex each unit has separate meters so that each unit gets its own electricity bill. However the entire centralized AC system is wired and  billed to the top floor ,the bottom floor has window AC unit and electric radiators, the AC vents in the bottom unit are freebies for the lower unit but they are controlled by the top unit.

I have an interesting situation with as my new tenant downstairs doesn't like window AC.Even though it's relatively cooler downstairs the lower unit tenant has a higher demand for cooling than the top unit,this wasn't the case with previous tenant.Makes me wonder if the lower unit tenant wants to ride on my back to pay his unit cooling bill. How should I resolve this issue so the bill can be divided up fairly.Appreciate your input.

Thanks.