Gotta jump in to recommend electric blankets!
I personally keep my propane heated house around 19 C and do use an electric heater that's also a fake fireplace in the living room when I wanna be extra cozy. Not sure about the efficiency, but it's pleasant.
Electric blankets are great for heating you (and potentially your feline friends) rather than the air.
We keep some electric blankets and space heaters around in case the furnace shits the bed or we have a power outage. We can power them from our mobile generator as we don't have a connection to the breaker box and the furnace won't burn with our power for the fan (rightfully so!).