Windows and Doors
We all want outside light to come into our homes and we have to have a way to get in and out of them. Windows and doors are a weak link in a homes thermal boundary because they can not be insulated as well as walls and they will leak air but you can have plenty of windows and doors and still have an energy efficient house.
Replacing windows and doors usually doesn't finish high on our energy audit recommendations because the return on investment for most homes is not as good as air and duct sealing. If you spend $5,000 for new windows and only get back a 5-10% savings per year in your electric bill it can take 20 years to recover your investment.
If you have aluminum single pain or windows that leak considerably and are beyond repair then the return on investment is much better and replacement windows may be a good option.
Doors usually have to be in really bad condition before they become cost effective to replace and replacing weather stripping is usually all that is needed. Sliding glass doors are very inefficient and replacing them with French doors usually have a reasonable return on investment.
Any time windows and doors are being replaced you always need to apply spray foam between the door and the wall to stop the leaks and improve the insulation.
| Type | R-Value |
| Aluminum Frame Single Pain | 0.76 |
| Aluminum Frame Double Pain | 1.14 |
| Wood Frame Single Pain | 1.1 |
| Wood Frame Double Pain | 2.04 |
| Vinyl Frame Double Pain | 2.17 |
| Vinyl Frame Triple Pain | 2.77 |
There are some new innovative windows that have up to an R-6 rating, of course you're going to pay more for them.