How Much Heat Do Your Windows and Doors Really Lose?
Energy efficiency isn’t just about marketing claims — it’s about measurable performance. Using a heat gun, we measured temperatures across:
- Walls with 2×6 insulation
- Triple pane windows
- Double pane windows
- A high-performance ProVia entry door
- Electrical outlets and trim
Our goal was to show what to expect from even high-performing windows and doors, and how heat loss varies in real homes.
Heat Loss in Homes: Understanding the Basics
No house is perfectly insulated. Heat escapes through:
- Exterior walls
- Windows and doors
- Trim and gaskets
- Electrical outlet boxes
Even energy-efficient windows and doors experience some heat transfer. The goal is minimizing that loss so your home stays comfortable and your heating system runs less often.
Real-World Testing: Doors and Windows
We tested a ProVia entry door on a cold (21˚F) day. We hope to see about a 10˚ difference between the temperature of any given surface and the indoor air temperature. We observed that the center of the door panel is where the least heat loss occurs – as you would expect, door edges and gaskets are where more heat loss can be detected. In this particular door, the glass inserts are performing almost as efficiently as the wall itself!
Next, we tested triple pane windows versus double pane windows:
- Triple pane windows performed almost as well as the insulated walls (only a few degrees cooler).
- Older dual pane windows had slightly more heat loss but still performed reasonably well.
Large picture windows and double hung units were compared to see how window type and size affect heat transfer.
Hidden Heat Loss Points
Surprisingly, electrical outlets on exterior walls can be significant sources of heat loss if they aren’t properly insulated. Small gaps around outlets and trim can impact the overall efficiency of your home, even if your windows and doors are high-performing.
Key Takeaways About Energy Efficiency
- Even the best windows and doors aren’t perfect. Expect some heat transfer.
- Triple pane windows perform exceptionally well. They can approach the efficiency of insulated exterior walls.
- Older double pane windows show moderate heat loss. Still better than single-pane alternatives.
- Heat loss is not uniform. Edges, gaskets, and outlets are weaker points.
This kind of testing helps homeowners understand the real-world efficiency of their windows, doors, and walls – and sets realistic expectations for energy savings.
Why Measurement Matters
Energy efficiency isn’t abstract. Seeing exact temperatures gives a clear understanding of how homes perform in cold weather. Whether you’re building a new home or upgrading, understanding heat loss helps make informed choices about windows, doors, and insulation. Want to learn more or assess your home? Give us a call! (978) 654-0275
