Hiya, it's a complicated calculation. But a loose lay insulation such as rockwool (energy intensive to produce) or sheeps wool or woodfibre will have a lower value but is better at reducing voids vs PIR. Difference in building energy use will likely prove negligible for a project this size. That's my 2 pence. Don't mean to derail the thread, which is awesome!
Hiya, it's a complicated calculation. But a loose lay insulation such as rockwool (energy intensive to produce) or sheeps wool or woodfibre will have a lower value but is better at reducing voids vs PIR. Difference in building energy use will likely prove negligible for a project this size. That's my 2 pence. Don't mean to derail the thread, which is awesome!