Hi Jackson,
Yes airtightness is pretty essential, my house I think must be really airtight it traps freezing air inside all year round great in summer, hell in winter.
I'm not fastidious about using only old materials (and recycled) but have noticed in many cases during renovating the old house that the original materials have been used for a very good reason and are really giving and durable.
Double & triple glazing is great and can be put on the inside without effecting the character of the building but also they had shutters, thick curtains, tapestries, wooden panelling, durable rugs etc. Maybe there is a way of combining old and new sympathetically.
I have noticed the heat retention quality of pure wool beats any number of duvets. Old woolen products should definitely be recycled and made into insulation. This could probably extend to all animal or human hair produced from grooming and hair dressing. I bet someone is doing this already if not perhaps I should set up a business!

Hi Nanos
Thanks for the link. If you want to build something quickly and efficiently then concrete does make it easier. Sometimes I get sick of pandering to the time consuming demands of this old house and it's repairs there is more to life!