Last month we called SCE&G about a free energy audit they were offering. We had been meaning to so something like this, but we were procrastinating and companies who do this professionally charge around $400 - so we opted for the free one. The inspectors came and looked around our attic and our crawl space. They inspected our A/C unit and water heater. We also discussed our windows.
Our water heater is a gas storage unit, which means it uses gas to keep a tank full of water heated all the time. It is 14 years old, which means it is near the end of its life. I'd rather take a little time and replace it now, than have to do something when it fails. SCE&G is offering financing if we replace it with a gas tankless water heater. There is also a rebate/tax credit we can take advantage of.
A few years ago I took it upon myself to insulate our water heater. I went to Lowe's and bought a water heater blanket and managed to wrap it around the tank - it was hard, because it was in a small, vented, metal box outside. After the inspectors looked at it, they said the insulation may be restricting airflow to the pilot, or something like that, and I should remove the lower part of the insulation. I did that later the same day and I think it has helped our hot water supply.