Improving Window Performance: Page 2 of 8

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Improving Window Performance
Shades, shutters, films, quilts, and more can give your old windows improved energy performance without breaking your budget.
Installing window films
Installing window films without leaving bubbles can be tricky—it’s usually a job best left to professionals.
New window putty
New window putty helps seal a window pane and minimize air leakage.
Fitting exterior storm windows
Fitting exterior storm windows in preparation for colder weather is often a rite of fall.
Operable awnings - open
Operable awnings can provide summer shade, yet be retracted for winter solar access, wind protection, or to avoid snow accumulation.
Operable awnings - closed
Operable awnings can provide summer shade, yet be retracted for winter solar access, wind protection, or to avoid snow accumulation.
Hinged shutters
These hinged shutters also have adjustable slats to let in some light and view.
Roller shutters
Roller shutters can provide effective shading and some ventilation.
Installing an interior glazing panel
Interior glazing panels are an inexpensive way to boost a home’s energy performance without compromising its architectural integrity.
Quilted window covering
Quilted window coverings and their valances can provide an attractive method to reduce heat loss through windows.
Insulated cellular shades
Insulated cellular shades contain multiple layers that produce a honeycomb-like structure that can add from R-1 to R-4 to a window’s thermal performance.
Improving Window Performance
Installing window films
New window putty
Fitting exterior storm windows
Operable awnings - open
Operable awnings - closed
Hinged shutters
Roller shutters
Installing an interior glazing panel
Quilted window covering
Insulated cellular shades

Drawbacks

  • Undesirable interior “mirroring” with interior films that have high reflectance
  • Reduced winter solar heat gain
  • Does not remedy air leakage
  • May reduce daylight penetration, so supplemental daytime lighting may be needed
  • Films require special procedures and chemicals to remove (should be done by professionals only)

Aesthetics

  • Darkening of windows (dependent on product—more transparent films result in little change in light transmission)

Tips & Cautions

  • Look for an NFRC rating label to verify performance properties
  • Look for a transferable lifetime warranty
  • Have films installed by a professional

When To Consider

  • Solar gain through existing window results in overheating or uncomfortable glare
  • Blockage of views with awnings or other window attachments is a concern
  • Large areas of glass that would be difficult or prohibitively expensive to replace or treat with other retrofits, such as storm windows or insulating blinds
  • Concern about UV fading of artwork and furnishings near windows

Where to Use

  • In sunny, clear-sky climates where overheating is a concern
  • For non-low-e films, use in climates with moderate to significant cooling requirements
  • Low-e films are suitable for use in all climates

Cost

  • $80 to $125 per window, contractor-installed; less for do-it-yourself

Window Restoration

A comprehensive repair can dramatically reduce air leakage through existing windows—and air leakage is often the biggest problem with older windows. Repairs typically include installing new seals or gaskets where the sash and frame intersect. It also may involve replacing the putty, which holds the window panes in place; and sealing and insulating window counterweight pockets (in older double-hung windows).

While skilled homeowners can undertake the work, it is usually best left to specialized contractors. In Europe, consumers can find patented systems for upgrading existing windows, including the Ventrolla System and Quattro Seal, but in North America this work is typically done by specialized contractors—found in areas where historic home preservation is popular.

Comments (7)

Edgar Zeitler's picture

Quick overnight response from these folks to my email inquiry about vertical blind slats.

Edgar Zeitler's picture

A very interesting product indeed, the videos on their website are informative. Just requested a quote for their vertical blind slats.

Robert Crosby's picture

I didn't see mention of a product called "solarize inflector", which looks interesting. It appears to be a reversible window insert that either passes or rejects radiant heat flow depending on which way it is turned.

Wondering if anyone here has experience with this product. Their youtube videos look impressive.

https://www.youtube.com/watch?v=B4Y...

Michael Welch's picture

Seems like a brand new product that might not even be available yet. The product's web site sure doesn't work.

Edgar Zeitler's picture

While living in Maryland I covered half my windows in each room with aluminum screen frames covered with clear heat shrink. The rest of the windows were covered with 1" styrofoam panels. Both installed inside. Really reduced heating costs even tho my windows were all double glazed with low E treatment. Easy to store between use.

IndowWindows's picture

Thank you for this informative article! There are so many other options than window replacements and I hate seeing those beautiful old windows go into landfills. Alternatives are more eco-friendly and can be just as efficient as a replacement. Save those historic windows!

samuel chamberlain's picture

One option which is not mentioned is the use of bubble wrap , this of cause is only suitable for out buildings or where the need for improved performance out weighs aesthetics . whilst it can be stuck to glass with water I have found that fixing to the frame is better as this cuts down on air leakage . The bubble wrap can be ripped/cut in case of emergency exit .

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