Answer: homemade techniques, especially boiling water in the room.
There are effective natural solutions to humidify a room that is too dry. Simply drying your laundry in the room is one example. But the most effective is to heat water in the room. The water turns into vapor which humidifies the room. For underfloor heating, place a large water tank on the floor where it will not obstruct passage. If you have a radiator, you can put a bowl of water directly on it. It is also possible to find suitable humidifiers at a low price (less than 10 euros). Tip: you can add a few drops of essential oils to the water. However, it is not recommended to do this in the presence of pregnant women and young children. Whatever the solution chosen, remember to close your door properly to keep the humidity in the room.