The graphic below comes from my friends at Ashbrook Roofing in the U.K.. For my U.S. friends, the figures are in pounds sterling rather than dollar, but the basic payback times won't vary too much.
Remember, sometimes it isn't about payback. It can be about comfort.
Nonetheless, if it is savings you want, it makes sense to start with the projects that promise the quickest payback first.
You might also consider those projects that you can do yourself. Payback is quicker if the costs are lower, so long as you do a good job.
If you want to know how long it will take for you to get a return on how much you paid for your insulation, then here is a quick guide for you to peruse at your leisure. It's always worth checking before you get the work done, as the return on insulation can vary dramatically:
If you get a jacket fitted to your hot water tank, it will pay for itself in six months.
Get your pipes lagged, and you'll be financially even within a year. The same applies for sealing gaps in the floor and skirting.
It will take two years to break even when it comes to having 0-270mm of roof and loft insulation fitted.
Cavity wall insulation will pay for itself within about three and a half years.
If you're having 100-270mm roof and loft insulation fitted, then expect it to pay for itself within five years.
Floor insulation can vary significantly in terms of how long it takes to repay itself - from two to 10 years.
Internal solid wall insulation will pay for itself in 15 years, but it will take an extra seven years on top of this for insulation fitted on external walls.
See original infographic: Ashbrook Roofing