Everything connected to the crank that is dragging its rotation consumes fuel.

More electrical loads/ Higher current draw = more resistance to alternator's rotational force.

Inclined roads, stop and go traffic, high-speed driving = more rotational force needed to move the flywheel.

Aircon compressor turned on = resistance in the pulleys. The lower the thermostat setting, the more and longer your compressor engages with the crank. The higher, does almost the same when your heater engages in a form of electrical load(heater coil).