I'd be interested in seeing an answer to this one, this is something I've been wondering about for a while. There seems to be a lot of advice on new builds only.

Yourhome.gov.au offers some advice for existing houses. Passive design does refer to thinking about items in the design stage. If you change your search terms to saving energy or money you may get more info on the net. If you have a specific problem, post that here with pics and you’ll get lots of suggestions.

I did have a look at Yourhome.gov.au and also found an interesting article at renew.org.au. All good information but I would still prefer to pay someone that specialises in the field just so I know I’m doing everything I can with the options available.

Seems to be a hole in the market that I’m surprised hasn’t been filled. There must be so many people in the same boat as me.