They call our grand-parents eco-warriors because they were frugal and recycled everything. That was not because they were committed conservationists, it was because during and after the great Depression they were dirt poor. Frugal usually means poor, and most people don’t want to be poor.
Yes — insulation of buildings has a place in conserving energy; even requiring homes to have 1 metre wide eaves would help a lot to keep the sun out in Summer, but let it in, in Winter. Passive Air-conditioning can be designed into buildings, and insulating can be retrofitted to existing building’s ceilings. Walls are harder to retro-fit, and would not give a ROI in most cases.
The other option is Solar Power: this works best on hot sunny days when Air-Conditioning is most needed: the supply fits the demand, and sufficient PV panels would take the pressure off the peak load on hot days.
Burning sawdust to kiln-dry your timber is a great idea, too. That kind of frugal I like.