How to Insulate Windows for Energy Efficiency and Peace of Mind

One of the reasons we have windows in our house is for mental health. Can you imagine what it would be like to live in a house with solid walls and no windows. I saw a similar living arrangement on T.V., they called it - being put in the hole - it was a movie about a prison.

When it comes to natural light and being able to see what is happening outside, windows would be hard to live without. When it comes to energy efficiency and energy conservation, windows are often a thermal flaw, a weak spot in the insulation system of a wall.

How to Insulate Windows.

One of the most cost-effective ways to increase the insulation value of a window is to install a see through covering over the window. I was in a drug store the other day and, to my surprise, ran into a display selling plastic shrink-wrap window covers. Kind of like aspirin for a window, medicine to help with the aches and “panes.” The plastic window cover captures a bunch of air between the plastic and the window glass that serves as an insulation layer. The Plastic is also great for stopping air leaks.

What is the insulation R-value of a window?

New types of windows have R-values up to R-8, but most windows are between R-1 and R-4. A window with a single pane of glass has a R-1 insulation value. A double pane window with low-e glazing and argon has an insulation value of about R-3.5. In comparison, a modern wall has much better insulation - about R-25.

How to Insulate Windows.

Remember the ads on TV about the wonderful storm windows from the store with the really thick catalog? They would handle the whole thing, from measuring to installation. Call the number on the screen for your energy saving storm windows today.

Storm Windows

Over the years, I have seen a variety of storm windows. Some are installed on the inside of the window and some are installed on the outside. The more expensive storm windows were permanately mounted and would open and close just like the window they were covering. Others were mounted with twist screws, put them on in winter and take them off in summer.

I’m not sure if you can find storm windows today. With the availability of the new vinyl, double pane windows, storm windows have gone the way of the Oldsmobile. Anybody know if you can still get storm windows made-to-fit?

Real glass storm windows maybe a thing of the past, but the plastic ones that you buy in a kit and cut-to-fit have gotten better. I like the one with the plastic snap bead you install around the inside of the window casing and then snap the plastic into the bead. It’s a do-it-yourself project that is very effective at increasing the insulation value of a window.

Why is the space next to a window so much colder?

Windows affect comfort more directly than other building components because of their low thermal resistance and high solar transmittance. This means that the window has a lower R-value which allows heat to escape and the ability to let the suns radiation in which heats the house up.

During winter, windows cool the body down by sucking the heat right out of us. Remember, air moves from hot to cold - so our heat radiates toward a cool window. Also, cold window glass cools the air next to the window and causes that air to fall towards the floor. At the floor, it warms and rises towards the ceiling where it cools down a little and falls, right pass the cool window to the floor again.

This is called a convection loop and is a major reason why you don’t feel warm sitting next to the large picture window to read the paper. Not only is the air cooler, but it is moving too.

How to Insulate Windows.

Window Covering With Insulation

Insulated drapes are an effective way to reduce the cool feeling from convection loops and the problem associated with radiating heat from an unsuspecting body. Insulating drapes are also successful at stopping the unwanted solar rays during a hot summers day.

The drapes are often constructed from several layers of tightly knit fabric. Using a variety of clips, magnets, plastic beads, or Velcro straps, the curtains are held snugly to the window casing for a tight fit. When desired, the curtain can be unzipped and opened to let the light in or to see what the dog is barking at.

With insulated drapes, a good program is open during the day and closed at night. I think your neighborhood department store is more apt to carry insulated drapes these days than storm windows.

How About Window Film?

Sitting up on a hill near most towns, you can see the newer homes with the vaulted ceilings and the tall picture windows looking down over the valley. A whole wall of windows standing erect like a granite rock in Yosemite. As I look up from the valley floor, I try to see the people running around inside and I wonder, how do they close the drapes on those high irregular shaped windows to keep the midday sun from cooking everything insight?

After having the opportunity to visit some of those homes, I have discovered that midday cooking is real and drapes is not the answer.

Window Film Protection

How to Insulate Windows

In the last 10 years or so, window film applications have made huge strides to meet the increasing market. Window film designed to reduce the undesirable effects of the sun comes in a wide variety of shades and solar control. Like a good pair of overly expensive sun glasses, window film can reduce the transmittance of harmful rays, like the ones that turn your carpet a different color, and the Film can reduce the suns heat radiation to reduce solar heat gain.

Behind the tall wall of windows, window film allows the light in, but keeps a lot of the heat out. By choosing a lighter shade of film, the people in the house can still spy on the valley and the Valley people can still try to see the people.

Windows are a very important part of any house. They are also, too often, an important part of an inefficient house. Replacing windows is not always a cost-effective measure if you are just talking about dollars and cents, but they are almost always a comfort-effective measure. If your not ready to replace an older window with a new double pane window, there is still plenty you can do that will increase the energy efficiency and comfort of your home.

Thank you for stopping by Detect Energy, hope to see you again real soon, but I won’t leave the light on for you...

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Comment by Don Ames on January 30, 2012 at 12:06pm

Hey Bud,  I really enjoyed your vision on the "windows of  the future". Not only could the flat screen window provide needed light, but it could show any outdoor landscape you desired. Provide egress by some other means and you don't have to downgrade the thermal envelope by installing a window. Surprised at the Fire Marshall decision, if a person can't figure out how to get through some plastic film, how are they going to know enough to operate the window?

I will check out the science of hot air rising soon, today's a little busy. Thanks for the comment and sharing, look forward to hearing from you again.  Don Ames

Comment by Bud Poll on January 30, 2012 at 10:06am

Hi Don, great article.

One of my favorite comments about today's windows is that technology may one day make them obsolete.  If you are reading this on a flat screen, you are probably looking at the energy efficient window of the future.  Imagine the largest flat screen we have today installed on a basement wall with a selection of cameras mounted around the house so you could enjoy the view of your choice.  You could even log into an online camera and watch the sun rise in Eastport Maine, then set on a beach in CA.  Where a basement is often perceived as a dungeon, the improvement would be obvious, but the security, energy efficiency, and variety of views would also make them attractive in the rest of the house, time will tell.  Of course we would still need faux windows on the outside for the neighbors to think they are looking in.

As for improving the existing windows I do like the shrink films, but I ran into a concern.  The fire marshal in my great state of Maine has decided that those film applications are a hindrance to an egress window.  The decision hasn't stopped the sale of these kits, but it did stop a senior support group from trying to help by installing these kits for those who can't.  Now, I totally disagree, but in any event, the liability has now been shifted back to the installer or one who advised they be used.  FYI, I still recommend them, but I include the caution above.  Besides it would only apply to egress windows so all the others are fair game.

Now, since you are a prolific writer, I would invite you to visit my thread on, "The Science of Hot Air Rising".  Besides sorting out the forces behind air flow, I will be introducing some suggestions for our energy language.  Call it being "Energy Correct" but as professionals it is to our advantage to be certain what we say is technically correct.  Our readers are often smarter than we are and will judge us by the mistakes we make.  To point out, warm air does not move to cold air.  Warm moves to cold, but warm air moves only when pushed by cold air or when forced by the mechanical devices we use.  If you would like to discuss it, send me a friend request and we can talk.


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