As the leaves begin their colorful transformation and the crisp, familiar air of fall settles in, it’s time for us indoor creatures to think about staying warm without sending our heating dollars out into the cold. This October, we’re turning our attention to one of the most underestimated energy drains in your home: your windows.
Why Windows Matter More Than You Think
When nor’easters start howling, your walls hold their ground—but your windows? They act like wide-open invitations for cold air. A typical single-pane window has an R-value of just 1, compared to your well-insulated walls at R-30. Even newer windows usually only reach R-3 or R-4. It’s no wonder that up to 20% of your heating bill slips right through the glass.
You might assume new windows are the obvious fix, but with quality replacements averaging $1,000+ each, the cost for an average home quickly climbs over $20,000. That money is better spent on higher-impact insulation or air-sealing projects.
Luckily, we Mainers have a local, affordable option: WindowDressers, a nonprofit that builds custom interior inserts for older windows. These inserts double your window’s R-value, cut drafts dramatically, and cost a fraction of replacement windows. A community build is happening this December in Wells—but you’ll need to register by early November so volunteers can measure your windows.
Your October Challenge: Become a Window Detective
Before breaking out the tools, take time to diagnose your leaks. Air loss typically happens in two places:
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Where the window sash meets the window frame, and
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Where the window frame meets the house framing
Double-hung windows have an additional weak point where the two sashes meet.
The Smoke Test
This simple test reveals where outside air sneaks in:
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Close all windows, doors, and vents.
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Turn on exhaust fans to create negative pressure.
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Hold a smoke pen or incense around window edges.
If the smoke dances or pulls in a direction, you’ve found a leak. On cold or windy days, the movement becomes even more pronounced.
DIY Fixes That Actually Work
1. If You Don’t Need to Open Windows in Winter
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Insulation Film Kits
Create a tight, clear “bubble” over the window. Small R-value gain + great air sealing. -
Interior Window Inserts
Custom-built wooden frames with dual plastic layers.
Excellent for drafty double-hung windows. (WindowDressers specializes in these!) -
Caulking Cord
A removable, putty-like seal for gaps around window sashes. Great seasonal solution.
2. If You Do Need to Open Windows in Winter
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Tubular Adhesive Weatherstripping
Ideal for sealing top and bottom sashes. -
V-Seal Weatherstripping
Perfect for double-hung window tracks. -
Draft Stoppers
The classic “door snake” for windows—simple, but not a complete solution.
Sealing the Window Frame to the House
Behind every window trim is a gap—often 1–2 inches wide—between the window frame and the house framing. In older homes, this space is frequently under-insulated.
Best practice:
Remove interior trim and insulate with:
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Low-expansion spray foam, or
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Backer rod + caulk
Easier option (no trim removal):
Caulk:
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Where trim meets the wall
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Where trim meets the window frame
It’s not perfect, but it can block significant air movement.
Improving Insulation (Increasing R-Value)
To boost heat retention:
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Cellular (Honeycomb) Shades
Can add R-2 to R-5. Prices range $35–$350. -
Thermal Curtains
Multiple insulating layers. Cost varies widely ($30–$300), but proper installation is key.
🎁 October Member Benefit
Our friends at Eldredge Lumber and Hardware are offering EcoHomes members 10% off select weatherization products mentioned above!
Just tell the cashier you received an email from EcoHomes—the eligible items will be on display near checkout.
Your October Action Plan
Week 1: Perform the smoke test
Week 2: Measure windows + plan materials
Week 3: Use your EcoHomes discount at Eldredge
Week 4: Install your air sealing or insulation upgrades
Bonus: Register for WindowDressers for custom inserts
The Bottom Line
A few hours of window work this fall will:
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Increase comfort
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Reduce heating bills
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Shrink your carbon footprint
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Leave you with the satisfaction of a job well done
Think of every draft you seal as plugging a tiny hole in a boat. One might not sink you—but together, they make a world of difference in keeping you warm, dry, and financially afloat.
If you want a deeper dive into techniques, This Old House has an excellent instructional video to guide you step-by-step.
Stay warm, stay cozy, and let’s make this winter your most energy-efficient yet!
