From a perspective that may be only relevant to my wife and I, and as Glort says, maybe out of a lot of peoples price range (fark, am I really implying I agree with Glort!!).
We are currently designing a new house that we will want to keep as a semi-permanent Oz residence (intention is to spend the Oz summer here, and the winter in the south of France).
So we are going as power efficient as we can, which includes solar power / hot water, under floor solar heating (requires double concrete pad with insulation between), double glazing, vaulted ceilings with north facing glass, and the list goes on.
Sure it will add quite a bit up front to the cost of building, but this is for retirement. So anything that can be done now while income is not limited to reduce the draw on a self funded pension and give us more in spending money on a weekly / monthly / quarterly basis is worth it anyway you look at it.
The cost will also be offset to some degree by the size of the house, kids are gone, so we are going for a small compact house instead of the sprawling joint we have now, and also on a smaller block as we cant be arsed with the whole gardening / weeding thing.
We were asked why the heating aspect if we will not be here for the winter, case of hope for the best, plan for the worst, Europe may turn to shyte and Oz will become permanent (or vice versa, going by the current government).
I guess what I am driving at is yes it will cost you in a one off, likely take a long time to recoup the outlay and the upkeep should be kept in mind, but the benefit of extra bucks in your hip pocket each week going forward should not be over looked (spiraling cost of living, and not just utilities, but food, water, fuel, taxes etc).
I could not care less about money back from excess power generated as you can bet that eventually the rebates will be gone altogether sooner or later, and no rain water tanks either, I pish more than we get in rain in WA except for about one month a year.
