Very serious, RMCF - in general it costs money to save money.
It all depends on what you want to put your money into.
Mechanical and electrical items cost more, by weight, than building materials - and usually must be maintained annually or bi-annually and replaced after about 15-20 years.
Solar panels can break, turbines can be damaged, etc.
Orientation a building to avail of southern exposure costs nothing.
Designing the opes to maximise solar gain costs very little.
Placing a building to avoid severe exposure may cost a significant amount, depending on the internal road access.
But these are not variables in an existing house, they're a given.
You can change windows specification, and sizes and even location - at a cost.
Airtightness canalso be improved, but this is a very diligent whole building operation and can cost money in drywall construction - wet plaster internals are inherently more "sealed", but once you seal a house you must ventilate it in a controlled way.
That's a whole other discipline, involving sealing up chimneys, choices between active and passive or hybrid stack systems, internal sealing membranes, external weathering membranes, secure fixing of insulation in cavities, full cavity fills - there is a lot.
The one thing that can be increased, at a reasonable cost, for both new and existing hosues and that will cost very litte in maintenance fees over the years is insulation.
Can I respectfully direct you to the ConstructIreland website where you should read a few of the articles.
Jeff Colley's team od an excellent job of promiting sustainable architecture.
http://www.constructireland.ie/
Plus its a good read.
I am subscribed to their magazine, no other connection.
Finally can I also suggest you research a utility-bill based retrofitting scheme announced at last years Plan Expo in the RDS.
There is a scheme supposedly online now, where retrofitting insulating is paid for through your utility bills.
I think the theory was that it would be charged at a rate not exceeding what you saved on heating.
That way your heating bills didn't go up, and your house was better insulated.
I'm sure any of the retrofit companies will advise you on grants, etc.
ONQ.
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All advice on AAM is remote from the situation and cannot be relied upon as a defence or support - in and of itself - should legal action be taken.
Competent legal and building professionals should be asked to advise in Real Life with rights to inspect and issue reports on the matters at hand.