WEBVTT - What is Low-E glass?

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<v Speaker 1>Welcome to Brainstuff from house stuff works dot com where

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<v Speaker 1>smart happens. Hi Am Marshall Brain with today's question what

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<v Speaker 1>is low e glass? So if you were to go

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<v Speaker 1>today and try to replace the windows in your house,

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<v Speaker 1>or if you were buying a new house and you

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<v Speaker 1>look at the windows they've put in, you're gonna hear

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<v Speaker 1>about low e glass, and the question would be is

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<v Speaker 1>it worth the money? Because low e windows cost more

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<v Speaker 1>than normal windows. So if you were to stand outside

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<v Speaker 1>in sunlight on a normal sunny day, you're being exposed

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<v Speaker 1>to three different types of light. There's infrared light, visible light,

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<v Speaker 1>and ultra violet light. When you're inside and looking out

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<v Speaker 1>through a window, you really only need to see the

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<v Speaker 1>visible light in order for the window to do its job.

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<v Speaker 1>The window can go ahead and block all the ultra

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<v Speaker 1>violet light and all the infrared light and you'll still

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<v Speaker 1>see the same thing through that window. The advantage of

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<v Speaker 1>blocking the ultra violet light is that it prevents color

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<v Speaker 1>fading and things like your rugs and your furniture and

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<v Speaker 1>whatever you have hanging on the wall. The advantage of

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<v Speaker 1>blocking infrared light is that it keeps summer heat outside

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<v Speaker 1>the house and it helps keep winter heat inside the house.

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<v Speaker 1>In other words, it improves the energy efficiency of the window.

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<v Speaker 1>There are articles on the web that demonstrate the difference

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<v Speaker 1>that low e glass can make to winter comfort. For example,

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<v Speaker 1>let's say it's zero degrees outside and the wind is

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<v Speaker 1>blowing at fifteen miles, so it's cold and it's windy,

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<v Speaker 1>and you were to look at the temperature the glass

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<v Speaker 1>inside your house. If you just had a normal single

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<v Speaker 1>pane of glass and you took its temperature, it would

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<v Speaker 1>actually be at twenty six degrees would be below freezing,

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<v Speaker 1>and you could have frost forming inside your house. Obviously,

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<v Speaker 1>if you were to stand next to that window, it's

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<v Speaker 1>gonna feel cold because it is cold. It's it's lower

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<v Speaker 1>than freezing. If you were to put in normal double

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<v Speaker 1>paned glass and measure the temperature of the glass, it

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<v Speaker 1>would probably be at about thirty five degrees, just above freezing.

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<v Speaker 1>If you stood next to that window would still be cold.

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<v Speaker 1>Now there's two types of low E glass you can buy.

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<v Speaker 1>There's hard coatings, which is a very very thin, transparent

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<v Speaker 1>layer of tin on the outside of the glass. If

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<v Speaker 1>you were to stand next to a hard coded low

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<v Speaker 1>E double pane window, that glass would be at about

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<v Speaker 1>fifty degrees Fahrenheits something like that, so it's better. You know,

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<v Speaker 1>it's warmer than the glass from a normal double paned

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<v Speaker 1>window or from a single pane window. By a long shot.

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<v Speaker 1>It would still feel cool standing next to that window,

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<v Speaker 1>but not nearly so bad. And then there's another kind

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<v Speaker 1>of low e called a soft coating, where they put

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<v Speaker 1>a very thin layer of silver on the inside of

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<v Speaker 1>those double paned windows, so the space between the panes

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<v Speaker 1>they put a very thin silver coating there, and when

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<v Speaker 1>they do that, the windows glass on a zero degree

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<v Speaker 1>day outside is above sixty degrees. It's you know, nearly

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<v Speaker 1>the same as the room temperature. So if you were

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<v Speaker 1>to stand next to that window, you'd feel a slight

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<v Speaker 1>difference in temperature. But that low e window with that

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<v Speaker 1>silver soft coating on the inside of the glass, creates

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<v Speaker 1>a window that is practically as good as the wall.

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<v Speaker 1>It's just a very good insulating window. So you can

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<v Speaker 1>see there's a huge difference between just a single sheet

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<v Speaker 1>of glass and these low e double paned windows. That

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<v Speaker 1>tin coating, as I said, is known as a hard coating.

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<v Speaker 1>The over is known as soft. Obviously, silver is better,

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<v Speaker 1>but tends to be slightly more expensive, and it pays

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<v Speaker 1>to know the difference, because if you can get a

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<v Speaker 1>silver coated window of soft coating at a decent price,

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<v Speaker 1>it's gonna have better insulating properties. That same kind of technology,

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<v Speaker 1>by the way, is how they make one way mirrors,

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<v Speaker 1>the kind of glass you see in an interrogation room

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<v Speaker 1>or something like that, where it looks silver on the

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<v Speaker 1>side where the prisoners sitting, and it looks clear on

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<v Speaker 1>the side where the investigators are sitting and watching the prisoner.

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<v Speaker 1>It's just that the coating on these low e windows

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<v Speaker 1>is much much thinner, so it doesn't have that mirror

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<v Speaker 1>look to it. It's just helping to absorb that infrared

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<v Speaker 1>light as it's going in and out of the window.

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<v Speaker 1>One thing to keep in mind is that these metal

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<v Speaker 1>coatings on the glass actually do reduce some of the

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<v Speaker 1>visible lights. So when you look out the window, you

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<v Speaker 1>aren't really going to be able to tell it with

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<v Speaker 1>your eyes, but if you were to is a light

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<v Speaker 1>meter or something like that, there's less sunlight coming through

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<v Speaker 1>because the metal blocks a little bit of it in

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<v Speaker 1>the same way that a one way mirror blocks light.

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<v Speaker 1>That metal reflects some of the visible light as well,

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<v Speaker 1>and you might get fifty less visible light through a

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<v Speaker 1>low e window then you get through a normal window.

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<v Speaker 1>Like I said, it looks the same to a human eye,

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<v Speaker 1>but if you have house plants, it's not going to

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<v Speaker 1>look the same to them. If you're replacing a single

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<v Speaker 1>pane of glass with these fancy double pain are gone

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<v Speaker 1>filled low e windows, plants inside the house are going

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<v Speaker 1>to see a decrease in sunlight, and you may want

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<v Speaker 1>to take that into account. You probably want to have

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<v Speaker 1>lower light house plants inside your house if you're gonna

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<v Speaker 1>put in low e windows. For more on this and

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<v Speaker 1>thousands of other topics, does that how stuff works dot com,

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<v Speaker 1>and don't forget to check out the brain stuff block

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