1/2 -- Why?
We think that climate change is a serious problem. We wanted to see if we could do something about green house gas emissions on an individual basis.
The other reason is economic. It seems likely that fuel prices will continue to rise, and they may rise a lot. We have achieved a $4,000 reduction in yearly energy costs with the projects we had done so far, and avoided some future fuel price increases.
To us, this seems like a win-win situation -- reduce green house gas emissions and keep our energy bill from going through the roof.