Doors and windows (Part 12 Home Energy)
Typically, a new window or door job has a terrible return on investment. The window industry certainly has some great advertising, because more often than not people think they need new windows. If you have old wood-frame single-pane windows, you are better off caulking, weather-stripping, and adding storm windows. If you already have double-pane or better windows, then simply caulking and weather-stripping, if needed, is sufficient.
Doors are in a similar situation; just weather-strip and make sure the door sweep is in good condition. The only time it makes sense to replace a door from an energy saving standpoint, is when an interior door is used as an exterior door, but even then the ROI is not great. This is sometimes true if you have a door to the attic or to the garage. New window jobs are typically not done if ROI on energy savings is a consideration. See below:
ROI new windows: 3% AVG