If you have shopped for windows lately, you have seen Low-E mentioned everywhere. It stands for low-emissivity, and it is one of the main reasons a modern window keeps a house warmer than an old one. Here is what a Low-E coating actually is, how it works, and when it is worth having.
What a Low-E Coating Is
Low-E stands for low-emissivity, which is a measure of how much heat a surface gives off. A Low-E coating is an ultra-thin, invisible layer, often made of silver or metal oxide, applied to the glass. It lets visible light pass through so the window still looks clear, but it reflects the longer wavelengths of heat. The coating usually sits on a surface inside a sealed insulated glass unit, where it is protected.
How It Works
Heat moves through a window in a few ways, and radiant heat is a big one. In winter, a Low-E coating reflects indoor heat back into the room instead of letting it escape through the glass. In summer, it reflects some of the sun’s heat away, keeping rooms cooler. The result is a more even indoor temperature and less work for your heating and cooling. It is the same idea that makes choosing energy-saving windows worthwhile in the first place.
Types of Low-E for Different Climates
Not all Low-E is the same. In a cold climate like the prairies, a high-solar-gain Low-E is often used: it holds heat in but still lets some of the sun’s warmth through to help in winter. In hot climates, a low-solar-gain coating blocks more of the sun’s heat. There are also hard-coat and soft-coat versions, with soft-coat giving better results inside a sealed unit. This choice pairs closely with the double-pane versus triple-pane decision.
Does Low-E Reduce Light or Views?
A common worry is that a coating will make windows look dark or tinted. In practice, Low-E is nearly invisible and only slightly reduces the light coming through, far less than a tint. Most people cannot tell a Low-E window from a plain one by looking, except that the Low-E one feels warmer to sit beside in winter.
Do You Need Low-E?
For almost any home in a heating climate, yes. The energy saved over the life of the window easily outweighs the small added cost, and most energy-saving replacement windows include Low-E as standard. If you are replacing windows and comparing options, it is one of the features worth confirming is included, alongside the sealed unit and a good frame. If you are weighing it up, our residential window team can explain what suits your home.
FAQs
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