We need to replace the windows on our home. What's the greenest choice?

Asked by Lisa Fiocca, Stow, OH

We will be putting new windows in our 1948 Vero Beach, Florida home. Do we want double-paned or is single-pane okay? Also: aluminum or vinyl-clad?


Daniel Glickman

Answered by Daniel Glickman

Sherborn, MA

Sustainable Construction Services, Inc.

May 21, 2009

Windows in an older home can be a significant source of energy loss due to low R-values and air leaks. In sunny locations, solar gain can have a significant impact on energy efficiency and comfort.

  • If your home is to benefit from the full potential of window replacement, the new window must address these issues.
  • Typically, Energy Star–rated windows do just that!

Energy Star-rated Windows

If you are simply looking to update your windows, you really can't go wrong with properly installed, double-glazed Energy Star–rated windows.

  • In addition to making financial sense, these windows increase dwellers' comfort. Less energy is required to keep your home cool in the summertime and warm in the winter. 
  • Condensation on the interior surface of the glass is also minimized.

But the quality of installation is critical: air-sealing edges and insulating weight pockets (if your window has these) are extremely important steps.


Now to address your question about the type of cladding on the exterior of the window. The purpose of cladding is primarily to protect the window from the elements.

  • Most windows come with the option of aluminum, fiberglass, or vinyl cladding. There is a lot of talk about how vinyl is a toxic material and should be avoided for environmental reasons.
  • In my opinion, aluminum and fiberglass are the better options, but you really can't go wrong with cladding.

Heat gain

If your home has serious problems with solar heat gain, you should really consult with a firm that specializes in energy modeling.

Using computer software, an energy auditor or other green professional can estimate how specific improvements will affect the comfort and performance of the house.


For more information:

The Energy Star website offers energy-saving tips and information on tax incentives for installing energy-efficient windows, doors, or skylights.

To learn more about window replacement, read Susan Davis's "Should I choose vinyl or non-vinyl replacement windows?"

Tagged In: energy efficient window

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