Can't argue with a 3cm-thick layer of cork

[Garald]

Of course I also put seal around the edges.

 

 

Well, it is one way to deal with an outside metal door that was either uninsulated or very poorly insulated. Is there really another way, given that the door couldn't be opened (it was soldered together)?

 

3cm-thick cork means R=0.75.

A new, properly insulated security door would have cost around 4000 eur, or so the locksmith tells me (one can find somewhat lower values at https://www.m-habitat.fr/portes/prix-porte/prix-d-une-porte-les-tarifs-selon-le-type-1629_A)

- and the R value would not necessarily be higher; any door with an U lower than 1.7 counts as insulated over here, and 0.75 is clearly greater than 1/1.7 = 0.588...

 

I'm putting a home-made thermal curtain (lots of Climashield apex inside a William Morris curtain, with reflective insulation between the laters) on top - but the stuffing keeps sliding down; I'll need to take the curtain to a retoucheur.