Household heating in Russia generally city-wide. E.g. there is a "котельная" wich fueled by gas or oil where water is heated and then hot water goes to apartment buildings by pipes. In my town we have gas-fueled power plant there water is used for cooling generators and then this water used to heat nearby buildings (it heats almost half of the town actually). When electricity was switched off lately (because of ice on wires) problems with heating occured only in places there hot water pumps were electric-powered. And even in such places they were quickly switched to diesel generators and heating was restored.