Windows play a vital role in maintaining an ideal temperature indoors. But the question is how? Window glass has a coating that reflects heat back. Once such a layer is Low-e. Low-e (low-emissivity) glass is widely used in modern homes. Such glasses have a thin coating that helps to keep the space warm in cold months and cool in warm months. However, most of the homeowners find it difficult to locate the Low-e side of the glass. This blog explains everything about Low-e glass, its properties, and some simple ways that can help you find the Low-e side of the glasses.
What is a Low-E Glass?
Low-e in a glass stand for low emissivity, which means a very thin coating applied to glass, mostly on the interior side of the outer pane for double-pane windows. This coating is made of metallic particles which reflects radiant infrared energy from the outside while still allowing natural light to enter the home. If you're using a heater in your home, it helps to reflect the heat back into your home, keeping it warm.
Properties of a Low-E Glass
Properties of a Low-e glass are discussed below:
- It is proficient at reflecting infrared rays, meaning it can directly reflect far-infrared radiation.
- Low surface emissivity E absorbs very little external heat and, as a result, radiates very little thermal energy.
- The broad range of shading coefficient Sc controls the amount of solar energy transmitted, depending on the region.
How to Identify Which Side of Glass is Low-E?
Use a Match/Lighter/Pen Light
The easiest way to distinguish the flame colors and identify the Low-e side of the glass is to use a lighter. You can also use a match or a penlight. All you have to do is just place the lighter close to the window glass and keep an eye on the four reflections of the flame (two for each panel). If any of the four reflections seem to be a different color, it indicates a Low-e coating on your window.
Bright Spotlight Indication
If your glass shows a very bright spotlight that strikes the glass obliquely, it indicates that the Low-e side is on the outer side of the pane. The inner side of the glass pane appears a bit milky. This is also an easy way to find out the Low-e side of a glass.
Fingerprint Test
Put your finger on the outer pane of the glass of your window and look for a dual reflection of your finger. If you find a secondary reflection of your finger, it indicates that your glass has a Low-e coating.
Reflection Test
Another easy way to find out the Low-e side of your glasses is to do a reflection test. This process is somewhat similar to the spotlight indications test, which was already explained in this guide. To find out whether your window glass is Low-e, turn on your cellphone flashlight and hold it up to the window. Four reflections of light will appear in a double-pane insulating glass unit. This happens because of the four levels of the insulating glass unit. If your window has a Low-e coating,then one of the four images will have a different color. However, if all four reflections are of the same color, then the window doesn't have a Low-e glass coating.
How a Low-E Glass Function in Summer And Winter?
In winter, the temperature inside the home is higher than outside, and the far-infrared heat comes from indoors. A Low-e glass reflects this heat back inside, preventing the indoor heat from escaping. Additionally, Low-e glass allows solar radiation from outside to enter indoors, and this energy is absorbed by indoor elements. This heat energy is then converted to far-infrared heat and left inside.
In summer, outdoor temperatures are higher than indoor temperatures, and far-infrared heat radiation mainly comes from outside. Low-e glass reflects this heat back, preventing it from entering the home. Low-e glass with a low shading coefficient is needed to prevent solar radiation from entering. This will help limit the entry of solar radiation into the room, thereby minimizing cooling (air conditioning) costs.
Conclusion
A Low-e side of a glass can be easily identified using simple techniques such as a match, a lighter, a penlight, a spotlight, a finger test, or a reflection test. Detecting the Low-e side of the glass has various benefits. The Low-e side reflects back UV rays of the sun and controls the transfer of solar energy. In winter, Low-e glass prevents indoor heat from escaping, while in summer, it reflects heat back so your interior stays cool. Therefore, indicating the Low-e side and setting it up properly will enhance daily comfort year-round.
