Meanwhile in NYC: my apartment is regularly heated to 85 degrees in the winter, and it's commonplace to open the window and let in some freezing air to fight the radiator.
(Relatedly, I wonder what effect the current pandemic will have on the modern trend of well-sealed homes...)
Every apartment I've lived in around NY and North NJ was like this. All had steam radiator heaters, and the heating was so hot, especially in the fall and spring, that you controlled the temp by opening or closing the window over the radiator. All but one also had single pipe radiators[0], so you couldn't turn them down with the valve or you'd end up filling the radiator with water and breaking the system.
However parts of NYC do still have steam heating powered by a central plant (mostly ConEd iirc) so in the end it might actually end up more efficient with the windows open than having a per unit heater.
Edit: Wikipedia link on NYC's system https://en.wikipedia.org/wiki/New_York_City_steam_system
I guess it's just Manhattan that has central steam, but it also provides cooling via absorption chillers and steam for disinfection. Also much of this steam is basically a waste product of electricity generation, so the actual efficiency may be even higher.
Edit 2: I also found and article in NY Times that supports the spanish flu as the reason for this, and also describes 1 vs 2 pipe systems.
[0] https://www.nytimes.com/2016/03/13/realestate/radiators-stea...
Here's an interesting article about Spanish flu and radiators: https://www.bloomberg.com/news/articles/2014-02-17/our-indis...
"engineering manuals from the 1920s dictated that radiators and boilers be manufactured large enough for 'the coldest day of the year, with the wind blowing, and the windows open.'" (!)
We're building 600 hp electric cars these days.