I keep my windows cracked in the winter despite having control (and payment responsibility, mind) of our heating. It's worth being able to think clearly all winter: https://www.yaleclimateconnections.org/2016/07/indoor-co2-du...

Depending on your climate and what you mean by "windows cracked", you would be much better off with a heat recovery ventilation (HRV) system. They have the explicit purpose of pulling in outside air while only losing about 20% of the heat difference between indoor and out.

With slightly open windows, you're losing a bunch of heat for very little ventilation.

Unfortunately I don't own the building but thanks for the info about HRVs

Another thing that strikes most Russians when they go abroad is how well ventilated the buildings are, and how high is the indoor air quality.

In Russia, it's most likely an inverse of venue class. Malls, public venues, indoor markets, govt buildings all like to save on ventilation.

'Shared heating' needn't mean no control over the heating.

Many buildings in Denmark are supplied with heat (for room heating and hot water) by a municipal system, but each house or apartment can adjust the temperature of the room heating, with radiator valves or electronic thermostats.

We're charged based on how much heat we extract from the system.

a hundred years ago they thought fresh air was an important part of staying healthy, so building heating systems (those big cast iron radiators) were designed to heat effectively in winter with the windows open.