The Importance of Proper Fitting Windows & R-Value

Back Deck

Delving into the world of windows and R values can be a daunting task.  We found this calculator, that will help you compare overall R values with the entire wall assembly, to help you determine what R values would be most beneficial and cost effective for your home or project.  It may seem very technical and difficult to grasp, but it is an exercise well worth pursuing to help make your home the most comfortable and energy efficient it can be.

With just a 15% window to wall ratio windows represent a gaping thermal hole in your home’s exterior. This thermal calculator developed by Cascadia Windows and Doors compares overall R-Value of the entire wall assembly with various wall and window insulation levels. Check out the calculator; as an example take an R-3 window representing 15% of the wall area: we can invest substantial cost to go from an R 16 wall to  an  R-39 wall with only a marginal increase in the overall wall assembly R-value (R12-R16) In other words, we’ve more than doubled the wall insulation at substantial cost and only realized about a 27% improvement in overall wall assembly R-value due to the impact of much lower R-value windows. With these same assumptions, we can increase the R-18 insulated wall over 300% to R-60 and only get a 40% improvement in overall wall assembly R-value (e.g., R-12 vs. R-17). Now look at the power of high-R windows. We get nearly the same overall wall assembly R-value with an R-6.5 window and R-18 insulated wall as an R-3 window and R-60 insulated wall (e.g., R-17 vs. R-18). Yes, windows are a really big deal!

Try out the calculator here

Posted: Monday, June 15, 2015