An eco retrofit adventure

I’ve thought for sometime how great it would be to self build a property to Passiv Haus standards, and with all the trimmings.  It would be made of the most natural long-lasting, reused / reusable and innocuous materials I could find, and with the future built in.  Well of course this comes at a price, and one currently beyond my reach.  However an opportunity to tackle the next best thing as I saw it, a home retrofit, has captured my imagination.