Splitting utilities for In law

[Chris Perrin]

Hey everyone, I’m looking for some advice on how to split the utilities for the in-law apartment. The apartment is not individually metered but is on its own water heater and has its own central ac unit, my side of the house does not. Outside of getting it metered, which I have looked into, does anyone have any ideas of how I could fairly split the  gas and electric bills? I appreciate any help!