I think even half the rent for those days would be too much, especially if this is a higher priced rental.I'd roughly base it on how long it is out for, how many people are living there, and what would it cost for a cheap take-out or "pick up from the grocery/warehouse store" dinner 3-4 times/week. 

Currently, the owner pays all utilities.Clearly, it's not ideal to only allow one tenant to control the temperature (which is what the current set up is).

Depending how high your rent is I had a good experience with renters warehouse.

Cap rate has been a quick way to take the temperature on my ROI of the my funds in the purchase and it's return as an investment, without clouding it with all the other moving parts.At the same time, cash-on-cash interests me less, as mine isn't particularly impressive.

Combination of truck docks, small size, Low roof/low doors, large office space too big or small- tied to a warehouse, looks like an elevator shaft on the roof. 

Unused factories and warehouses in industrial areas can also be re-vamped for housing.

Shopping centers, single-tenant buildings, apartment complexes, office, warehouse, etc.

Insulating the side of the foundation as is shown in this drawing (which may not be 100% of what you have, but illustrates the point) is also a temperature control strategy.

Looking to connect with other members doing commercial office/warehouse deals in WA state under $750K.

They have institutional backing from possibly a large fund, hedge fund, warehouse lines of credit, or large business lines of credit.