Concealed insulating window shutters.

I'm in the middle of a largish project - insulating my house - it's currently got 50cm stone walls, and a total of about 13 windows, with no insulation between the stone, and the plasterboard. This is bad.

So, I'm putting in 10cm of rockwool, and kingspan round the windows - as I only need to cut it in 5cm to get equivalent insulation.

I recently wondered about something that would be almost free at this stage. ( - well, maybe 80 quid for the kingspan)

Shutters, concealed against the inside of the stone wall, that slide out along the front of the windowsill, and completely close off the window opening.

Construction would be something like a block of 5cm kingspan, the size of the window opening, with 4mm ply all round it.

outside #########-------############### #######K| |K############# #######K| |K############# #######K| |K############# (# = rock, R = rockwool, K = kingspan, #######K| |K############# S = shutter - halfway slid in) RRRRRRRK| |SSSSSSSS| RRRRR RRRRRRRK| |KKKKKKKRRRRRRR ________| |_____________

Not to scale - for most of the windows, the opening is maybe a meter by

I could of course do the trivial solution - which would be drawer slides across the windowsill, and the top.

Does a neater way occur to anyone?

Of course, this would need reasonablish ventilation to outside, per alcove, and tight fitting of the shutter, to avoid condensation on the window. (and vapour barriers as normal of course)