Our loft insulation was provided free by the council so there was no choice in the materials, but rolls of sheep’s wool insulation such as Thermafleece is a (surprisingly expensive) option that’s pleasant to work with and has very low embodied energy. That means not much energy is used in it’s manufacture, unlike boiling lava rock for mineral wool, or glass fibre.
For the couple of rolls of top up insulation I bought from the DIY store, I opted for recycled plastic.
The Internal Wall Insulation was woodfibre boards + lime plaster.
There is an external woodfibre system available but as well as being far more expensive than conventional materials it would require the roof to be extended, which is difficult on our hip roof. So we compromised on natural & breathable on the inside front & rear, and conventional on the outside on the end wall.
Loose Fill Insulation
We used insulation made from recycled newspaper under the floor.
You can use it in roof spaces so long as the roof is securely weather tight, but it’s not recommended for our tiled roof that is not under felted, because if a tile comes loose the rain comes straight in.