Insulating your home is, on average, the highest return-on-investment upgrade you can make. Here's the short history of why: in 1992, the Energy Policy Act first legislated that homes must have appropriate insulation. Then in 2012, the International Energy Conservation Code raised the bar sharply — a home built to the 2012 residential code is 32% more efficient than one built to the standard from just six years earlier.
That efficiency is money. The Southeast Energy Efficiency Alliance found it means a homeowner pockets anywhere from $218 to $1,588 each year — between $4,763 and $33,105 over the life of a typical mortgage.
If your home was built before 2012, you can likely improve your energy use greatly by updating insulation and air sealing. You wouldn't be alone: the Insulation Institute reports 89% of homes are underinsulated.
Sources: Southeast Energy Efficiency Alliance, “The Fall and Rise of Energy Conservation Codes”; Insulation Institute.