See if you can get a historical expenditure for this utility and take that yearly cost and divide it by the total SF of all units to get a per SF cost of gas for the building, then multiply by the SF of each unit for a monthly cost for each of the 4 units, themselves. 

Since you're 6-12 months away from buying, use this time to build investor relationships, master deal analysis, and secure financing.

And if they seem open to it be sure to follow up every two months or so.

@Jim LynchSome typical minimum tenant screening requirements look like the following, but it depends on your market:-Renter has a gross monthly income of 3x more than the monthly rent-Minimum credit score of 650-Renter must have no prior evictions-No felons (or other notable criminal history)There are a number of different tenant screening softwares out there such as Zillow Rental Manager, TransUnion SmartMove, etc.Be sure to complete an employment verification by contacting the renter's employer and confirm the details they shared with you, landlord verification (if they have a previous landlord), credit check, and background check.

Amazing that this is the only business in America where you are providing a service for free at the moment.

If a person has to ask, at all, I STRONGLY advise to use a PM service for tenant placement. 

Quote from @Jokari Trueheart: HI, almost 11 months ago I purchased 3 duplexes and I borrowed the funds from my personal residence which I took out a equity agreement for the down payment on the investment property, great idea at the time because I have 10 years to pay it off and theres no payment requirement, but , I learned more about the consequence that it takes a large chunk of my equity the longer I take to pay it back, so my goal was to refi cash out the investment property to pay it back but I don't think theres enough equity yet to pull the full $106k needed, I only borrowed $88k but with the equity percentage for one year i'm paying about $18k in equity on top of the amount I borrowed if I pay it off in year one, so I need this paid off ASAP before it increases more.

Make sure it explicitly explains the process for termination if you are unhappy with their services, especially if they violate the terms of your agreement.3.

You would basically offer the same set up utilities but you would have a residual income monthly by renting the plot to the owners of the space. 

As long  the tenants pay the rent each month, increasing their rent will be very tough and getting them to leave will be extremely tough.