Most heat transfer in our homes happens through the windows. During the summer, the windows bring heat into the home from the warmer outside (unless you live somewhere particularly cold), and in winter the warmer air indoors from our heating systems escapes through the glass panes.
Insulating windows is a great way of lowering energy bills and preventing your home from overheating too much if you live somewhere with a hot summer.
You can buy window insulation kits, but sometimes, materials you have around the home are just as good. One of the most popular is Saran wrap – though any plastic wrap will do, you don’t have to buy the brand name.
Here’s a quick guide to how effective Saran wrap is, and how you can install it in your own home.
Is Saran Wrap Good For Insulating Windows?
Saran wrap can be used to insulate windows, but it’s not the most effective solution. It will add a small amount of extra insulation to single-pane windows but is unlikely to be effective on double or triple-glazed windows unless it helps cover a crack.
There are two ways that plastic wrap can help with insulation. The first is by helping to cover any tiny gaps in the glazing that you can’t see. If there is a hole, no matter how small, then air (and, by extension, heat) will escape through it.
Saran wrap or cellophane will at least cover that, and if you stick it on tight enough then it will prevent the air from escaping.
The second way that plastic Saran wrap can help is because it’s made from a material that is less conductive than glass. Glass is a material which conducts heat quite well, so if your home is warmer than the outside air then the heat will pass through it.
Adding a less conductive material, such as clingfilm or Saran wrap, slows down that transfer of heat. Of course, it only slows it down marginally because Saran wrap is so thin.
That’s why bubble wrap is a more popular choice for many people who are energy-savvy. The material that bubble wrap is made from is slightly thicker plastic – it has to be, or the bubbles would likely pop when they were used to wrap something during shipping.
And then those bubbles also add an extra layer of trapped air to act as an insulator.
However, it’s easier to get Saran wrap – you may already have a healthy supply, and if not it’s usually cheaper. You can pick some up when you’re next buying groceries or just order some online.
How To Saran Wrap Windows
There are two ways that you can add Saran wrap to your windows. You can either stick it straight onto the window, or you can double-layer it, and then use tape to stick it to the window frame.
If you opt for the single layer, it’s easier since you can stick it straight to the window – providing it doesn’t stick together, which you know is likely possible. There is a trick to that though – more on that in a moment.
If you decide to double-layer it, you can get a thicker insulation layer, and you can trap an air bubble between the windowpane and the plastic for even more insulation. However, it needs to be stuck to the frame with a sealed edge all around, which impacts its look.
Here’s how to do a single-layer Saran wrap window insulation:
- Put your Saran wrap in the freezer for about an hour. This is a good trick that stops it from sticking together when you unroll it.
- Once it’s ready, remove it from the freezer and roll it out. Cut it to the right length for your window. If it’s not wide enough to cover it in a single sheet, measure out two.
- Acting quickly, before the wrap warms up too much, take it to the window. Make sure the window is free from any condensation and is clean.
- Press the Saran wrap against the window in one corner. Then using something with a hard edge, work the Saran wrap against the window, avoiding leaving air bubbles. Something like a credit card could work. Don’t be too rough though or you’ll tear the plastic wrap.
This last step is optional, but really the only reason you would do a single-layer is if you didn’t want it to be visible.
Air bubbles would actually add more insulation, but they don’t look very nice. So it’s up to you. Maybe leave the bubbles on windows in rooms where you don’t spend much time.
Some people also recommend using a hair dryer or some other heat gun to gently heat the plastic wrap and shrink it into place. You may not need to do this, but it’s something you could try as a final step if it looks to be sagging. Just be careful not to melt it off the window!
The important thing is to make sure there are no air bubbles around the edges. You want a tight seal to prevent warm air from directly touching the glass.
Here’s how to add double-layered Saran wrap to your window:
- Put the Saran wrap in the freezer for an hour still. Yes, this time you want the Saran wrap to stick together, but in a neat double layer. So this will still help.
- Once ready, cut the wrap to length. You need it to be double the length of your window pane, plus a couple of inches extra, since you’re sticking it to the edges of the frame.
- Fold it over before it thaws so that you’ve created a double layer.
- Take it to your dry, clean window and use tape to stick it to one edge of the window frame, making sure there are no gaps and the seal is tight.
- Work around the window frame, sealing an air bubble against the glass and making sure there are no gaps when you tape the plastic to it.
Pros and Cons Of Saran Wrap Window Insulation
Of course, Saran wrap window insulation isn’t for everyone. So, should you try it? Let’s take a look at the pros and cons to help you decide…
Here are the benefits of using Saran wrap to insulate your windows:
- It’s cheap – Saran wrap costs around $4 a roll for the and a single roll could do most of the windows in your home. Compared to dedicated plastic window insulation kits which can cost $10 for a smaller roll, this is much better value
- If you install a single layer and do it without any bubbles, there will be no impact on visibility and guests will never know you’ve added it to the windows (unless they touch it)
- It’s easy to peel off, and won’t leave any marks or residue behind when you do
- It can prevent mold – condensation forms on the window (particularly single pane windows) when hot air meets cold glass. The plastic Saran wrap doesn’t get as cold, meaning condensation doesn’t form, and when there’s no moisture on the frame then mold is less likely to grow
Here are the downsides of using Saran wrap to insulate your windows:
- It’s only effective on single-glazed windows and it’s not too effective at that for insulation – other methods will save you more on your energy bills
- It can be tricky to install, even if you use the trick of freezing it before you start
- It takes a lot of time to install it without any bubbles, if you don’t want anyone to see it
- Once you’ve peeled it off, it will cling together and you can’t re-use it
The Bottom Line
Saran wrap, or any other clingfilm, is one of the cheapest options available for insulating your windows, but it’s also one of the least effective. However, that doesn’t mean it’s not worth considering.
As well as being cheap, it’s also good for ensuring you don’t lose any visibility through the window. If you have a nice view then you don’t want to spoil it with bubble wrap or some other insulator that obscures everything.
If you like the idea of cutting down on heat loss through your windows, and preventing mold too, and you don’t want to spoil the look of your windows at all then give Saran wrap or generic cellophane a try. Even if just in the guest bedrooms, out of the way.
If you’re a little hesitant to try it and don’t mind spending more, then a window insulation kit may be your best option…