Heat Loss/Gain Help
The most heat loss in winter and the most heat gain in summer is through the windows of your home. The designation for insulation property “strength” is called the R-Value.
R STANDS FOR “RESISTANCE OF HEAT”.
The walls, if 2×4 studs, typically have R-ll fiberglass insulation in them. There is some R-value in the exterior and interior covering, which slightly raises the number. 2×6 stud walls can have R-19 fiberglass insulation in them, but let’s look at windows:
R-VALUES OF WINDOWS
| TYPE OF PANE | SUMMER | WINTER |
| SINGLE PANE | R = 0.96 | R = 0.9 |
| DOUBLE PANE W/ ¼ ” AIR SPACE | R = 1.64 | R = 1.72 |
| DOUBLE PANE W/ ½ ” AIR SPACE | R = 1.78 | R = 2.04 |
| TRIPLE PANE W/ ¼” AIR SPACE | R = 2.27 | R = 2.56 |
| TRIPLE PANE W/ ½ “ AIR SPACE | R = 2.56 | R = 3.22 |
What can be done for winter or summer to increase R value?
It is expensive to replace windows and the cost takes time to recuperate from the savings in heating or cooling expense.
- A sheet of plastic over the window (with an air gap) can save as much as 20% on the heating bill. It can be removed easily. What is even better?
- Foam can be installed over windows, using Velcro for the attachment. Sticky-backed Velcro adheres well to the window, but not as well to the foam and some superglue can be spread in the middle of the sticky back Velcro, to attach it to the foam (NOT on the window). Foam also allows light to come through, so that you don’t feel like you are living in a cave. It will be darker, however.
- The R value of foam depends on the thickness. 1-inch may be an R value of 7, and 2-inch thickness may be 14, depending on the quality of the foam. From the table, you can add the window R value to that of the foam.
Attaching to the window with Velcro enables its removal, which is especially advantageous for a renter. If the Velcro strips are too small, the foam will fall off, so be sure nothing breakable is near the window in case that happens.
Use more or longer strips as needed, to prevent the avalanche.