To start, the reluctant is the part of the wall under the window, which is removed to make a door. I found this word in the bills of the house, centenarians, I do not know if it is still current?
(I found the construction invoice file, in 1897-98, and some big 1936 modifications ...

There is everything, detailed as they knew how to do it at the time, I'll show you if you want!)
The walls are made of lime-washed rubble stones of a thickness 50 cm.
The reluctors have a thickness of 20 cm., Right below the Monnetier rock window frames.
1- Almost all radiators are placed here.
2- In the kitchens, there are pantries and the radiators are elsewhere against the wall.
1- Without insulation, the outdoor surface temperature in very cold temperatures exceeds 4 ° than the wall temperature. (+ 2 ° with a thin reflector insulation behind the radiator.
2 - In the kitchen, since we are more numerous and more cautious than a hundred years ago, it condenses to the point of getting wet on the floor in the cold.
I start replacing the windows and I ask myself a lot of questions.
If I isolate the reluctant too much and its outside surface temperature drops below that of the wall it may become wet and freeze?
I notice that the exterior facade is damaged, cracked or downright more plaster, behind unheated contrecoeurs!
A +, looking forward to reading you.