Low E Glass: Will it Save You Hundreds a Month on Your Energy Bill?

Are you shopping for new windows and overwhelmed with all of the lingo?

Low E glass, Argon filled windows, double-pane vs single-pane. it’s enough to make any sane person go cross-eyed.

Low-E is a common feature in windows that especially tends to confuse homeowners. Let’s go over what Low E is and if you should get it in your next set of windows – and does it actually save you money on your energy bill?

What is Low E Glass?

In a nutshell, Low E glass or Low-emissivity glass is a window that has a thin coat on it that causes it to reflect more heat. What does Low E stand for? Emissivity is the ability of a material to radiate energy. The value ranges between 0, which is a perfect reflector, and 1, which is a perfect emitter. The higher the number, the more the material radiates energy. Low-emissivity windows are better at insulating your home and reflecting heat.

graphic depicting energy reflection vs energy emission

From the perspective of energy saving, windows are a huge weak point in your home.

They are at a major disadvantage compared to your insulated walls. With a few panes of thin glass they are supposed to keep out heat in the summer, keep out the cold in the winter, and reduce ambient sounds from your neighborhood.

But we still need natural light in our homes and we don’t want to live a dark box so we still need windows.

So to make up for the poor insulation, we use a useful feature called Low E to improve how effective they are. Low E is a thin coating on the windows that make the them reflect more heat.

Low E = Low Emissivity

High emissivity basically means more heat will pass through, which we don’t want.

Low emissivity means less heat will pass through, which we DO want.

For example, uncoated glass has a high emissivity of around 0.96. This means that 96% of the heat passes through the glass, and it only reflects 4%. This doesn’t sound too great, right? It’s not.

Coated glass has a low emissivity of 0.05. This means 95% of the energy is reflected off of its surface.

Bingo. That’s what we want.

This sounds like a lot of science. The main takeaway is: the lower the number, the less heat that will enter your home in hot weather.

Low E glass just means that your window has a coating on it that makes it have low emissivity. This coating is microscopic and isn’t visible to the human eye.

There are 2 types of coatings: a soft coat or a hard coat. A soft coat is applied to the glass already made. A hard coat is fused with the glass while the glass is being made.

Many of today’s windows have a soft coat applied to the windows.

Advantages of Low E Glass

When talking to a window company or window contractor, they probably are assuming that you want the Low E glass. There are many advantages to it, whether you live in a place with hot or cold weather.

1. Protects Your Family and Furniture

Low E windows protect your skin and furniture from UV rays from the sun.

UV stands for ultraviolet. These light rays exist below visible light, which means we cannot see them. They are the rays from the sun that causes sunburns.

Inside a home, UV light will fade your fabrics and wall colors. There are 3 types of UV rays, and they each have different effects. You can read more about UV rays at the WHO.

This is why we have to wear sunblock when we go outside, even on cloudy days.

Low E windows stop almost 100% of UV radiation from coming through your windows. You get sun protection for you and your house, nice!

2. Lower Energy Bills

Low-E glass by itself already does a lot to reduce the amount of heat that goes through your windows. When combined with other window technology, such as double-pane windows and argon-gas, your windows will let barely anything through.

You keep the hot heat out in the summer time, and you keep the warm air inside in the winter time. It’ll help with hot weather and cold weather.

Your HVAC units won’t have to work as hard, extending its lifespan and saving you money in the long run.

Of course, there are a ton of other factors affecting your energy bill as well, but having Low E glass helps with temperature regulation inside the home.

3. You Still Get Natural Light

Low E glass has a microscopic layer on top, so you still get natural light entering your home.

You may have heard stories of people complaining that their replacement windows are tinted green. This is because Low E coating naturally has a green color to it. The more coats of Low E, the more green the glass will look. But you also get better heat reflectivity too.

Many of today’s windows have 3 coats.

Not all Low E windows have this green coat. You can opt for 2 coats as well. Ask your local contractor for different options and for pictures of the windows of other projects to see if this is something you would be okay with.

Many Texas homes with replacement windows will vary from house to house and company to company. From the inside, the windows are colorless. However, from the outside, they do appear green.

You also have to take into account what’s behind the windows and what surrounds them. That can affect the tint and undertones of the window.

4. Compatible With All Window Types

Whether you have sash windows, casement windows, awning windows, or any other type of window, Low E glass will work with it. That’s because all you are changing is the coating on the glass.

Soft coats can be applied to any type of glass too.

Disadvantages of Low E Glass

Compared to advantages, there are very few disadvantages of Low E glass. However, these are still factors you want to consider when making the decision.

1. Decreased Natural Light

Before, we mentioned that letting in natural light is one of the advantages of Low-E glass. That’s because it does let it in compared to window coverings and shades.

However, you get a slight reduction in how much light comes through. It can range anywhere between 20-60% less light, depending on the options you go with. It does help to ask your local contractor specifically what you want.

You never want to say yes to something you’re not 100% sure about.

If I had to describe our replacement windows, it would be: a semi-cloudy day all the time. However, it’s sort of a nice thing to have here in Texas summers. We usually have our blinds closed because the light is so strong anyways. In places where there isn’t much sunlight to begin with such as Seattle, it would definitely appear drearier.

With no grids, looking out the windows is an HD experience.

double pane window looking outside

2. Higher Costs

Low-E coats do cost more for all of your windows to have it.

You don’t have to coat all of your windows with it either, there’s options to pick and choose. For example, maybe your living room area gets the majority of the sunlight compared to your bedrooms which have a tree in front of them. It would make sense to get Low E windows for your living room.

Despite being more expensive upfront, it may make sense in the long run because you get energy savings over time.

On average, Low E glass is more expensive than single-pane and double-pane glass because it’s the glass plus the coatings on top of it.

Here is a good chart of price comparisons on average of different glass types.

Does Low E Glass Cost More?

Low E glass does come with an additional cost per window. The difference may be about $20-$30 per window.

This cost is added on top of the cost per window you’re already paying. The additional cost usually pays for itself in energy savings in the long run, especially if you live in a hot place such as Texas.

A double-pane window may already cost you $300-$700 per window, depending on the size, materials used, and window type.

A large 2-story home may have 20 windows that needs replacing, which means you would add $400-$600 to get the Low E coating on all of your windows on average.

If you start with an electricity bill of $350 per month and it goes down to $300 per month, it would take less than a year to make up for that cost in energy savings. We’ve seen even better numbers in our home (with 30 windows) going from single-pane windows to double-pane Low E windows.

So it does cost more to get Low E glass, but over a long enough time period, you end up saving money. There are other factors that affect window pricing that may or may not be worth it, depending on your budget.

What Does Low E Glass Look Like?

The Low E coating is very thin. The major difference between window glass without a coat versus with is the tint or color of the glass at certain angles.

Below, you’ll see a picture of an open double-pane window with Low E coating. As you can see, the part where the two panes overlap have a significantly greener tint to it than just one pane. And then you can compare it to having the window being open as well.

It appears to be more “cloudy” in appearance. Seeing through it is very clear. If it’s a bright sunny day, the Low E coating takes away some of that intense harshness of sunlight.

picture of an open window with two panes on top, one pane in the middle, and an open window on the bottom

Does Low E Glass Have a Green Tint?

Low E coats have a green tint to them. Depending on how many coats of Low E you have one your windows, it may appear more or less green.

From the inside, this may not be noticeable at all. However, from the outside, there is an obvious green tint to the windows. Results will vary from contractor to contractor, so make sure that you talk to yours and ask questions before agreeing on your replacement windows.

It’s not just Low E that can give your windows a green tint.

Glass also has iron oxide in it, and that also gives it a green hue. When combined with multiple Low E coats, you do get more of a green effect.

Double-Pane Windows Vs Low E Glass

Both double-pane windows and Low E coatings serve as a way to make your home more energy-efficient and have a more regular temperature.

Double-pane windows are windows that have two pieces of glass with an inert gas sandwiched between the two. The gas improves the insulation of the window and decreases heat or cold from passing through them.

Low E is just an additional coating on top. You can have both double-pane windows with or without a Low E coating on top of it.

Double-pane windows can exist without a Low E coating, but a Low E coating needs some type of glass to apply to. It doesn’t exist on its own.

Unfortunately, you cannot apply Low E coatings to a window after it has been replaced. There is an alternative, although not as good, way to reduce heat that enters your home by using window film.

How Low E Glass Works

Low-E glass is a type of coating that is placed on top of glass windows. The coating lowers the amount of UV (ultraviolet) and IR (infrared) light that passes through the glass while letting visible light come through.

UV and IR light is not visible to the human eye, although it has damaging effects. UV light causes walls and fabrics to fade, while IR light is heat.

Low-E glass has a coating that is very thin and is basically transparent. It reflects long-wave IR energy, which is where heat comes from. Depending on the coating, it may also reflect short-wave IR waves as well.

Low-E glass is helpful in the summer time and the winter time. In the winter, the Low-E coating will reflect heat back into your home. In the summer, the glass will reflect heat back out.

graphic showing what light enters the home and what gets reflected through a window with low e coating

Is Low E Glass Worth It?

We’ve looked at the various advantages and disadvantages of Low E glass as well as its cost.

If you are looking to replace all of your windows because they are currently single-pane windows, then definitely consider adding Low E coats to your replacement double-pane windows. The difference in insulation and sound reduction that you’ll experience is well worth the investment. In the long run, the Low E coats do make up for themselves in energy savings.

If you are looking to go from double-pane windows to replacement double-pane windows with Low E coats, the difference may not be stark enough for you to consider that large investment.

In the end, look at your budget and your purpose for getting replacement windows. It also helps to discuss all of your options with a local contractor or windows expert to make sure that you get what you want out of your replacement windows.

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