No oil, heating powered by gas boilers.
Generator located on ground floor. There is a day fuel tank in the same room. If there is a fire alarm the valve drops and sends the fuel to the diesel tank in the basement.
The basement has a foam riser from outside and the outlet is positioned above the fuel tank. So firefighters can plug into it if needed.
However, I consider the generator a medium fire risk as it is well maintained and if a fire existed it would dump the fuel away from the engine. I believe that if a supression system was installed as well, this would mitigate any damage from an early stage.