Why the flat is too hot when it is freezing outside

Most Russian city flats are not heated by their occupants. Hot water is produced centrally — usually at a combined heat and power plant that makes electricity and heat at the same time — and pumped through insulated mains under the streets into every building on the network, then through the radiators of every flat.

That design has one consequence a visitor notices immediately: there is usually no thermostat. The system goes on across a whole city in autumn, on a schedule, and stays on until spring. A flat is therefore warm continuously rather than in bursts, and it is often warmer than anyone wants. The local solution is a window on the latch at minus twenty, which looks absurd and is entirely rational.

The trade-off is dependability against control. You cannot turn it down, and the two weeks before the switch-on in autumn can be colder indoors than the whole of January. In return, a block of flats stays warm through a deep cold snap without anyone doing anything, and heating is billed as part of the flat's utilities rather than as a fuel you buy.

This is also why cold-weather clothing works the way it does here: heavy on the street, stripped off indoors, with the metro and shops treated as heated links in the chain.

For the rest of what winter involves — the cold, and what people actually do about it