@Ricardo Sancez  Actually I doubt they have electric baseboards, what you are likely seeing is the gas fired hot water baseboard radiators.  

Hello,I had a tenant last winter and the heat in his unit was supplemented by the unit above him.It gets really cold down there in winter but he chose not to have free heat and sealed the vents tightly with an aluminum foil without  letting me know , I could have easily adjusted the thermostat to lower  per his needs if he had told me and supplemented my apartment above with any additional heat but he chose to seal without letting me know inspite of my warning later on and obviously it can have detrimental effect on the tubing inside the walls due to excess pressure build up.He also complained about high electricity Bill's (obviously he would incur high utility bills when he turns on his electric radiator without using the free heat he was getting) I ended up having an oversight from my end as I did not verify if sealing vent caused any damage . 

.- boiler heat with hot water radiators.

Hi All,I'm considering purchasing a 3000sqft townhome  to BRRRR that currently has window unit A/C and radiator boiler system for heat.

@Adam Kuszczak most major metro cities will follow the same pattern...the "inner city" will be largely original housing stock...late 1800s to mid 1900's...developments typical radiate from the city center with age...so, 1950's through 1980's built properties are usually 3-5 miles from city center with the newest concentration of properties outside of interstate bypasses (usually forming a circle or partial circle around metro areas)...there is infill building and exceptions to these rules, but property age will be your #1 determining factor of where the properties you are targeting will be located.Building materials and methods of construction (along with codes) were very different from one decade to the next, but homes are surprisingly sturdy and most anything can be fixed.

If it's a baseboard heat (radiators) then you can install "zone valves" for a very reasonable price.

they can be more efficient than modern high-efficiency furnaces in some cases but they take a bit of maintenance and the radiators can be cumbersome in the rooms.

Hello guys, I have radiator heating with oil tank (above ground) in my home which I put on sale.

If the light is not the problem, the other thing that they might be doing is minimizing radio frequency radiation (RF) while they sleep. 

And you don’t mention whether the heating system is forced air or a boiler with radiators.