(1) Disability bathroom and wheel chair access throughout the house including big doorways and at least one entrance with wheel chair access.
(2) Tile Roof with the house built strong enough to carry it, that is most of the reason houses these days have tin roofs, not the cost of the tiles.
(3) Good venting in the roof to get rid of the heat in summer and vents in the ceiling of every roof that can be closed for winter or partly closed so each room still clears the stale air trapped near the ceiling
(4) Most definitely solar and batteries and not connected to the grid, pay for itself in no time with the savings from not having to pay to get the wires to the house and never paying any network fees or electricity costs. By the way, the Tesla units don't have that ability, they are grid connect only
(5) Reverse cycle air con in each room but not ducted but rather the ceiling cassette units.
(6) An integrated air con and hot water storage heat pump system with electric back up powered via solar, easier than solar hot water and more versatile.
Big verandah all the way around to keep the sun off the windows and walls and provide an outside relaxation area no matter what the season.
(7) If you want under floor heating then you can only have concrete slab construction and that is very hard on the knees and ankles so a suspended timber floor over the concrete slab would be required and that sort of negates the heating side of it, unless someone has come up with underfloor heating for a timber floored house. Then I'd go with under floor climate control, so it can be cooled as well.
(8) Some where with a great view and lots of windows, the big verandah should save the need for double glazing.
(9) Induction cook top with gas back up outside under the back verandah via a big BBQ and that can double as the oven
(10) All cooking areas with range hoods vented directly out through the roof, not into the roof cavity, same for the bathroom and toilet
(11) A full size ensuite in the master bedroom and a walk in wardrobe, a normal ensuite the main guest room
(12) Water tanks, Galvo and painted inside. Forget about concrete or plastic, the water taste is definitely an acquired taste
As you can see, it is highly unlikely I'll ever be building again
