I have read a few topics on insulating wallpaper, some say its a good idea and others not. I live in a detached bungalow, which has cavity wall insulation, although the internal walls always seem to feel cold, when the outside temperature drops (especially now, with the onset of winter!) Our garage is attached to the bungalow, making one living room wall (the one attached to the garage) especially cold, as this is not insulated. It therefore suffers with condensation in cold weather and we are obviously losing heat through this. I know at some point we will have to get this wall properly insulated, but does anyone think that insulating wallpaper will be of any benefit and make the room warmer.
May I suggest that you buy an infra-red temperature gun. With this you can scan the walls and ceilings, and while holding the trigger it will show you the temperature of the thing being scanned. You can buy these on line for about £20 or so. If you use a infra-red scanner and compare it with a room temperature gauge you will find that as you work your way up a wall it will get warmer the higher you scan. You will also notice that the wall feels cold to touch, even though it is the same temperature as the air. You are after all comparing the wall with your body temperature.
It is unfortunate that many walls have been filled that should have been left empty, as damp exterior walls pass their damp through the filling into the inner wall and a wet wall is 4000 times better at passing heat to the outside than dry air.
Perhaps you should also buy a damp meter.
To get a really good idea as to how well the walls were insulated, you may be able to find someone with a thermal imaging camera, who will take photos of the walls, that will show where the insulation is wet or missing.
The insulation fixed to wall paper is only about 2-3mm thick as such it is a waste of time.