Seal windows: The paper trick shows whether you need to take action

A simple trick reveals whether you should seal your windows afterwards.Credit:Getty Images

Are you looking for ways to reduce your heating costs this fall and winter? Then you should seal your windows. We'll show you how to do this quickly, easily and almost free of charge!

In the frosty winter months, we are all looking for ways to reduce our electricity and heating costs - without having to freeze. Luckily, there are a few simple and effective tips that you can use to noticeably reduce your energy consumption in the cold season.

Windows are a big factor in heating costs. Poorly insulated, drafty windows are a real heat killer and a reason for high heating costs. We'll tell you how you can seal your windows in simple steps and how you can find out whether your windows need better insulation or not.

Sealing windows: yes or no?

You can use three simple tricks to find out whether you should seal your windows or whether they are already well insulated:

1. Read the U-value

Every window has a so-called U-value, also called a heat transfer coefficient. It indicates how well a window with glass and frame insulates. The higher the value, the more cold comes in from outside and the more room heat is lost through the window. Single-pane windows have the highest U-value at 5.6. They are often installed in old buildings and provide very poor insulation. The lower the value, the better:

  • Toughened glass 5.6
  • 2-pane insulating glass 3.0
  • 2-pane thermal insulation glass 1.2
  • 3-pane thermal insulation glass 0.6

The U-value must be specified by the window manufacturer. You can usually find it on the window frame in the narrow space between the glasses. But it can't always be tracked down. Then there are two more tricks to find out whether the windows should be additionally sealed.

2. The paper test

With a simple piece of paper you can test whether your windows are tight or whether you need to do it yourself. To do this, open the window and put the paper between the window frame and the window sash. Then close the window again.

If you can pull the paper out, then your windows are not sealed well and you should take action. If the paper cannot be pulled out, everything is fine. Do the paper test in several places on your windows.

3. The lighter trick

If you couldn't find the U-value, you can use a lighter to find out whether your windows are well insulated or should be sealed. To do this, hold the flame of the lighter close to the window.

It should now be reflected several times in the window. If the flame of one of the front mirror images is discolored, then it is probably a well-insulating heat protection glass.

Also read:

Sealing windows: Trick with children's playdough

If you have single-pane windows or drafty windows, you should also seal them. There are various rubber window seals available in hardware stores. These can be easily attached to the window frame.

There is a trick to finding the right seal for your own windows: put simple craft clay between the window frame and the window sash and close the window. When you open it again, you will have an impression of the necessary gap in the dough. You can then go to the hardware store and buy the appropriate rubber seals.

Also awesome:

Seal single-pane windows, almost at no cost

If you currently have to spend every cent and don't want to spend money on seals from the hardware store, you can insulate your single-pane windows using simple and very inexpensive means. All you need is bubble wrap, a spray bottle and water.

It's that easy:
Cut the bubble wrap to the size of the window. Now fill the water into the spray bottle and use it to moisten the window pane from the inside. As a final step, place the smooth side of the pop film on the window pane and press it down. The almost free insulation is ready!

Admittedly, this DIY window insulation isn't pretty as it obscures the view from the window, but it serves its purpose very well. If heating costs are more important than appearance, you should try bubble wrap.