There's probably a few lower cost things that I am overlooking, to the tune of netting out a few hundred dollars of savings after however many years they took to pay back.
In the UK, houses have energy ratings, which are largely not that useful, but they do allow estimated annual running charge.
The house that I live in we moved in and were spending ~1.7k on gas a year.
We needed to re-render the place, because it has a few missing pieces. we spent the extra £4 to put in 90mm of external wall insulation. We also had to replace the glazing. It was cheaper to get triple glazing (for some reason), however the results of that was that it was 6degrees warmer in winter, and 10 degrees (celcius) cooler in summer. Even with gas prices doubling, we spend about £70 on hotwater and heating.
There are electric floor heating graphene foils that put out 20w per sqm, they're more than enough, no moving part, no maintenance, no bs, not even 20% of the price of a hydro floor heating, you can even install them yourself
Same goes with the cinder block foundation. If insulated, it moves the freeze/thaw interface inside the block and then you end up with a failing foundation.
Where I am your house would flood when 80mph+ winds blow the rain up your walls.
The end result is you're going to make big lifestyle changes to accommodate the energy. For example everyone sleeping in 1 bedroom and only cooking with an electric pressure cooker or low and slow with an induction range.
There are passive houses built at 2000m altitude in the Alps, some are made of wood and have literal strawbales for insulation, there are no excuses left in 2026 not to build good houses, it's more economical, more practical, more comfortable, more ecological
A "properly insulated" house still requires something around 0,5 W/m2/K. Modeling a moderate 120 m2 house in the coldest months when the temperatures hit 15-20 negative you still need 2,5 kW of heat with domestic hot water on top. Put in the efficiency of a heat pump and you are still easily looking at half a mega watt-hour per month. ~1MWh for a whole house is very reasonable number during winter months, sans electric mobility.
That's entirely unrealistic to cover with batteries with current battery technologies alone, electricity generation is absolutely REQUIRED. Windmills can help soften the blow and storage needs substantially, but the TFA is about solar, which is effectively absent during the winter.
https://planthardiness.ars.usda.gov/pages/map-downloads
https://commons.wikimedia.org/wiki/File:USDA_hardiness_zones...
Any means to keep energy cheap and abundant must be by force because it is not a natural order.
Not everyone has the capital (even with gov subsidies) to make those investments, and it's generally the people who need to save a few bucks on bills the most that DONT have the money.
People still spend literal millions on poorly built and poorly insulated mcmansions today btw, it's not a money issue.
However, it's not that far off for retrofitting, if you do it when your siding already needs to be replaced. Add 3-5" XPS foam to the exterior of any standard house; if a basement you bring insulation several feet down and out below the ground. If cathedral ceiling, when replacing the roof you put 6-8" polyiso down over the sheathing before the new roofing material. If vented roof, get 1.5x code minimum blown in the attic. Air seal first, of course (1-hour of air sealing is the best ROI of anything you can do in an old house).
But nobody wants to put that money up.