Improving Window Performance: Page 8 of 8

Beginner

Inside this Article

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

  • May hamper egress
  • Usually requires seasonal installation and storage when not in use
  • May affect visibility (plastic panels may not be optically clear)

Aesthetics

  • Most, but not all, panels are relatively unobtrusive

Tips & Cautions

  • Clean windows and interior panels before installing
  • Use only cleaning agents appropriate for the type of glazing—check with manufacturer; be careful not to scratch plastic panels
  • Label panels for reinstallation to the correct windows and allow space for seasonal storage

When To Consider

  • If historic codes, covenants, or condominium association rules preclude installation of exterior storm windows
  • If you need additional window insulation on an upper floor where installing exterior storm windows would be difficult
  • If you are renting and don’t want to invest in more-permanent window treatments, such as exterior low-e storm windows
  • If existing windows are leaky
  • If climate is moderate or cold, and additional window insulation during the heating season is desirable
  • If window egress is not an issue

Cost

  • $60 per window (plastic); $120 per window (low-e glass)

Interior Insulated Shades & Blinds

Insulated shades and blinds can be installed on window interiors to increase insulation and provide glare control. Products without side tracks typically add R-1 to R-2 to a window’s performance, while products with side tracks may add as much as R-4. Most common are insulated cellular shades that expand when deployed, but can draw up, accordion-like (usually at the top of the window, though some offer bottom-up and top-down deployment). Some of these products contain multiple layers and produce a honeycomb-like cross-section when lowered. The shades are made to fit fairly tightly in the window jambs to limit airflow around them (and reduce convective heat transfer). Metalized Mylar film in the cellular structure insulates much like reflective bubble-pack.

Quilted window blinds roll up or fold into pleats like an accordion (and are usually hidden in a valance). They can be lowered at night to provide insulation or used during the day to block unwanted sunlight. Fill sewn into the quilted fabric provides insulation. A layer of reflective Mylar in the fabric helps keep heat in the room. The blinds’ edges fit into tracks to stop most air leakage.

Insulated cellular shades and quilted blinds only save energy and improve a home’s thermal comfort when they are used—and they have to be operated manually. To realize that benefit in the winter, for example, they have to be lowered at night and raised during the day.

Benefits

  • Provide privacy
  • Reduce nighttime heat loss
  • Minimize cold drafts
  • Reduce unwanted day and summer solar heat gain
  • Control daylight

Drawbacks

  • Require homeowner involvement to raise and lower
  • Fully deploying blinds eliminates views through windows
  • Less effective at blocking solar heat gain than exterior shading

Aesthetics

  • Quilted blinds objectionable to some because of utilitarian appearance
  • Greater variety in colors and styles available with cellular blinds than quilted blinds

Tips & Cautions

  • Consider product warranty; some companies offer term warranties (like five-year) or the better transferable lifetime warranties
  • Consider professional installation to ensure proper measurement and fit
  • Potential damage to IGU when insulated shades or blinds are deployed during the daytime with high-performance prime windows, because very high temperatures can be reached at the windows

When To Consider

  • If existing windows are old, leaky, and in relatively poor shape
  • If climate is cold and reducing heat loss in the winter months is a top priority

Cost

  • Approximately $225 per window for quilted blinds to more than $500 per window for designer cellular shades

Access

Alex Wilson is the founder of BuildingGreen, the Brattleboro, Vermont-based publisher ofEnvironmental Building News, GreenSpec, and LEEDuser.com. He is also president of the Resilient Design Institute.

Window coverings & attachments • efficientwindowcoverings.org

Comments (8)

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.

Fred Golden's picture

The 1" styrofoam will reduce heat gain on a sunny day, and yes reduce heat loss at night, or in the mornings/evening when there is no sunlight coming into the window. At the same time, not having daylighting can increase the use of interior lights and that can increase the electric bill.

So some sort of night time only shutters, or styrofoam installed each afternoon, and removed during daylight heating times would improve the heat gain while reducing heat loss.

My sister's home in Phoenix AZ has screens on both the opening and fixed windows. This reduces sunlight hitting the glass, and thus less heat gain to the windows. Air can still circulate to remove any built up heat between the screen and glass. She would benefit from styrofoam covering the windows, yet it would give a "Cave" like feeling too. She would rather have more daylight and higher A/C bill.

The electric shades also look very promising. I know people who have them installed on motorhomes, and there is a wind sensor that brings them in at 15 MPH winds to avoid damage to the awnings.

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 .

Show or Hide All Comments

Advertisement

X
You may login with either your assigned username or your e-mail address.
The password field is case sensitive.
Loading