This won't address your existing home, but investing an extra $10k in basic building materials during construction to create good insulation will have a much bi

This won't address your existing home, but investing an extra $10k in basic building materials during construction to create good insulation will have a much bigger impact on heat/ac saved than any tech solution. It's not complicated to build a home that is passively warm in winter, cool in summer - building companies just don't invest in it. Long term I think that will be a major shift our global society will have to make. The other thing is...your carbon footprint is impacted much more by buying goods that are shipped from overseas, taking trips in airplanes, and the unseen costs of all the products in your life than it is from the relatively small consumption of your home's water & electricity.