Glasses, like any other building materials, have a set of certain mechanical properties. Among them is thermal conductivity - an important characteristic. At present, energy-saving glasses, also called low-emission glasses, or selective ones, are common because of their ability to delay electromagnetic radiation of a certain frequency. Outwardly, they are difficult to distinguish from ordinary ones.
- - lighter or candle;
- - Night time.
Note that in the infrared, energy-saving glass works like a mirror in its mechanism of action, reflecting heat. This happens due to the application of a thin coating, imperceptible to the eyes, on one of the surfaces. In this regard, its ability to reflect heat rays increases.
In order to distinguish energy-saving glass from ordinary glass, carry out the following experiment. It is better to do this in the dark, so that the picture is more contrasting and bright. Turn off the lights in the room so that it is completely dark. Prepare a lighter or candle.
Bring a burning lighter or candle to the glass from the inside of the room and carefully look at the reflection of the flame on it. If you have an ordinary window in front of you, you will see two or three bifurcated reflections of the flame (this depends on the number of cameras in the glass unit). They will be exactly the same color.
If the window is with energy-saving glass, you will see in the window half of one of the reflections of a flame of a different color. It can have a greenish or bluish tint, depending on the spray used (a bluish flame is a sign of silver sprayed). The color change is caused by the ability of low-emission glasses to reflect the infrared spectrum.
In addition, some energy saving glasses have a reddish tint. Please note that other methods of checking glasses do not carry one hundred percent guarantee. So, the advice often found on the Internet: "stand near the window and try to feel which air flows from it: warm or cold", has no clear justification. Here it is necessary to take into account the fact how well the window is installed, which side of the world it faces, how close the heating element is to it. Therefore, the correct answer to the question of whether glass is energy-saving can only be given by the experience with a lighter or with a candle.