EcoSmart Stud 
When it comes to insulating exterior walls for any building the old adage is still very true: You’re only as strong as your weakest link, and for the exterior walls, window are the weakest link.
For a residential home, you can basically divide the exterior wall insulation into 3 sections:
- The chamber (the space between the studs)
- The framing (studs themselves)
- The windows
We can talk all day long about how we can improve wall insulation, but I don’t know too many exterior walls in a home that doesn’t have a window in that exterior wall. In my home that would be two walls total that have no windows.
Understanding the Window Insulation R-Value
Most homeowners are shocked to learn that the average double-pane, low-e window, the most common type installed in homes today, has a window insulation R-value of only R-3. That’s remarkably low, especially when your walls could be rated R-13 or higher. This makes windows the clear weak point in exterior insulation.
To really improve the exterior wall insulation of a home you need to upgrade to a R-5 triple pane window. That almost doubles the value of the weakest insulation point of the exterior wall section, which can easily be 10-20%.
Combining Smart Framing and Energy Efficient Windows
This is where the EcoSmart™ Stud (ESS) becomes an essential part of the equation. Since the ESS is a much less expensive way to increase the insulation value of the framing compared to continuous insulation (CI), we can upgrade the window insulation also! This how we get a 50-70% reduction in HVAC energy needs by upgrading the chamber, framing, and window insulation simultaneously. For less money than CI insulation alone!
Let’s put some numbers to that.
Window and Wall R-Value Comparisons
Let’s put real numbers to these performance improvements. The following window insulation R-value and wall system comparisons are based on a standard 16 ft framed wall section with 10% window coverage.
- Base Build: 2×6 framing, fiberglass batts, double pane window = R-8.65 effective insulation
- Upgrade #1: R20+7.5CI wall section with double pane window = R-11.2 effective insulation
- Upgrade #2: 2×6 ESS wall section triple pane window = R-14.25 effective insulation.
- Upgrade #3: 2×8 ESS wall section triple pane window = R-19.2 effective insulation
Best Energy Efficient Windows and Wall System Cost Comparison
Now let’s translate this into an actual home build. Part of this information is based on actual bids on a 2240 sq ft 2018 new home build.
- 2×6 framing, R-60 attic, R-20 fiberglass batts, Double pane windows. Base cost-$
- R20+7.5CI wall build with double pane windows. Adding up all extra labor and materials cost. Upgrade cost $11,500
- 2×6 ESS wall build: $1280 extra for 2×6 ESS, insulation upgrade $2500, Triple pane windows $2200. Upgrade cost $5980.
- 2×8 ESS wall build: $2240 extra for 2×8 ESS, insulation upgrade $3500, Triple pane windows $2200. Upgrade cost $7940
How Improving Window Insulation Saves Energy and Money
What do these numbers tell us?
- The 2×6 and 2×8 ESS wall systems with triple pane windows outperform CI walls with double pane windows.
- The cost is lower.
- The wall performs better.
- Your energy bills drop.
Pairing ESS framing with the energy efficient windows ensures your weakest insulation link becomes a strength. Add in spray foam and batt insulation in the wall cavity, and you have a fully optimized wall system.