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7 Steps to an Energy-Efficient House: 4. Windows

Replace existing windows with low-e double- or triple-glazed replacements

Better glazing and less infiltration. A new replacement window with properly specified low-e glazing can help lower your energy bill.
Image Credit: Fine Homebuilding

Editor’s introduction: With energy prices rising again, many homeowners are planning energy-efficiency improvements to their homes. But most people are unsure of where to begin, and even seasoned builders don’t always know which priorities should rise to the top of the list. Betsy Pettit, an architect at Building Science Corporation
, recommends starting where you can get the most bang for the buck.

Step 4: Replace your windows

With the bottom and top of the house sealed and insulated, as well as the walls, windows represent the next opportunity. Old windows often leak both air and water into the house. They might not open and close properly, and are sometimes be obscured by unattractive storm windows and screens that reduce the amount of light that can enter. Moreover, they rarely have low-e glazing.

Properly installed Energy Star (or better) windows seal the holes in the walls to keep out water and weather extremes. If high-quality glazing is specified, the windows can admit useful solar gain during the winter, while still preventing excessive heat loss at night. To prevent summer overheating, the best glazing for east and west windows is usually low-solar-gain glazing.

Properly specified new replacement windows should reduce your energy bills. Since replacement windows are expensive, though, don’t expect a fast payback on your investment. But if you decide to replace your windows, at least you can enjoy higher comfort from Day One.

This article is adapted from Betsy Pettit’s Remodeling for Energy Efficiency
in Fine Homebuilding


In Green Basics:


In Product Guide:

Window Shades

In Strategies and Details:

Upgrade Existing Windows

In Blogs:

Making the Case for Triple-Glazed Windows

Choosing Triple-Glazed Windows

Passivhaus Windows

High-Solar-Gain Glazing

Should I Replace My Windows?

Tax Credits for Window Replacement

Windows That Perform Better Than Walls

In Fine Homebuilding:

Get the Right Replacement Windows

Should Your Old Wood Windows Be Saved?


  1. AdrienneBurt | | #1

    Saving wood windows
    Before you rip out your old wood windows- read this from Fine Homebuilding:

  2. Anonymous | | #2

    flashing for new windows
    How would an installer properly flash a new window that is going in place of an old window? I have an old home and there is no window flashing. I've read that flashing helps drain water away from a home and so I'm curious how this can be added.

  3. GBA Editor
    Martin Holladay | | #3

    Flashing windows
    There are many resources on the Web that discuss window flashing. For example, you could click the "Builder Notes" tab on this page:
    The page has a video of Mike Guertin demonstrating window flashing techniques.

    However, here is the bottom line: window flashing is a technically complicated matter, covered in an ASTM standard that is hard to master (ASTM E2112). If you don't know how to flash a window, your best bet is to hire an experienced window installer who knows how to do the job.

  4. Daniel Morrison | | #4

    Flashing replacement windows
    There's also a short article here: about flashing replacement windows.

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