> there is no thermostat, just a radiator on 100% and an open window

Nothing wrong about it as water temperature in pipes is regulated based on the temperature outside if not at building-level (not uncommon) but at least at heat-station providing hot water to several buildings.

Cannot decide if sarcasm. If so: good one :)

The problem with USSR-style heating infrastructure isn't the heating (apart from unfiltered coal-fired powerplants), but the insulation. Commieblocks were made with almost none, and to this day in most of Russia and former USSR they are bare. It was cheaper to waste coal/gas/oil than to pay for proper insulation and they were built as "temporary solution to housing problem" after all.

When Poland got independent in 1989 and energy prices got real - everybody started buying cheap styrofoam and in a few years we cut our energy usage for heating 3 times. It was CRAZY inefficient because of the pricing of energy vs materials in Warsaw pact.

This "mass styrofoamisation" still haven't happened in Russia to that degree BTW. It's still wasting crazy amounts of energy in all these old commieblocks without insulation.

Fresh air and required heat isn't a bad combination. New York City radiator design was very similar after the 1918 flu.

Modern construction with heavy insulation certainly reduces energy use, but at the cost of air quality. Even more modern construction includes air exchangers, but there's a lot of buildings with insufficient airflow.