BFH,
I have gone down this path, and am a few years ahead of you.
Four years ago we bought a house built in the late 90s. It's in the coastal PNW and is reasonably well insulated using modern construction techniques, including double-pane windows and adequate attic insulation, but is not purpose built to be energy efficient by any means. It had an 85% afue gas furnace.
We installed 7500 watts of solar on the roof.
I wrote a thread about it, but the short version is that they have already paid for themselves in 4 years, and generate more power than our household uses. You can read all about it in that thread if you're interested in the details.
Since we suddenly had all of this extra electricity that was just going back to the grid at retail rates, we bought an electric car.
I wrote a thread about it, but the short version is that the car not only saves us money, it removed the largest remaining source of carbon emissions from our household. From both financial and environmental perspective, there was no better use of our surplus electricity than displacing gasoline.
We were still heating our house with that 85% gas furnace, so we replaced it with a heat pump. It's between 200 and 400% efficient for both heating and cooling, and removed the next largest carbon emission source from our household and replaced it with electricity. I wrote a thread about it, but I'm not sure where it is anymore. It might be linked in one of those two threads above. edit: I found it,
here you go.
After the addition of the EV and the heat pump, we're now barely producing more electricity than our household of five uses on an annual basis, but I'm expecting a larger surplus after my kids fly the coop. We are still using some natural gas, for our water heater. We still use some gasoline, for our infrequently used minivan and the lawnmower. We cook with electric, and I actually prefer the electric glass top stoves to cooking with gas. Gas stoves pump moisture and combustion products into your house.
We also had the house air-tested for gaps when we had the heat pump put in, and did the usual sealing around outlets and door cracks. We have not added any new insulation to the attic or walls or floors.
The house has great southern exposure with no shade, so we get enormous solar gain the winter and our panels have a clear view of the sky all day all year. In the summers we block all of those windows with shades, but it still get hot without AC. Solar gain works both ways.
All of these changes required large amounts of money out of pocket up front, and even though they have paid for themselves by now there is a common argument in some circles that environmentally conscious folks should pay for carbon offsets and continue to burn carbon themselves, because it is more cost effective on a per-pound of CO2 basis to pay someone to plant trees than to replace your furnace. I find that argument self-defeating, though, because ultimately we will need to reduce our consumption somehow, not just increase our carbon capture rates. Paying to reduce your personal emissions is a very real and immediate step in the right direction, and I think that setting that example for your neighbors and your family, to make real change, is worth the cost. It's always easier for wealthy westerners to buy indulgences and make no changes to their lifestyles, but I'd have trouble sleeping at night with that half-assed solution.
