Your Guide to Low-E Coatings

By: Architectural Visions

There are many factors to consider during any home renovation, and energy and heat loss are important considerations. The very purpose of a home is to protect residents from nature’s elements. When it comes to windows and doors, a homeowner must consider how much heat is being let in from the outside and how much heat generated inside the home is being let out. In fact, windows and doors account for roughly 70 percent of energy loss in a home. Furthermore, glass in windows is responsible for 90 percent of heat loss. So, while windows are critical to a home as our viewing portals to the outside world, we must account for how well they are protecting us from that world.

Therefore, homeowners need to educate themselves on energy efficiency as well as in different energy efficient glass. Some popular and rather effective types of energy efficient glass to consider are the variations of Low-E Coatings.

Here at AVI, we have the know-how and expertise to help educate you about home energy efficiency, energy efficient glass, and Low-E glass. Here, we’ll guide you through what these terms mean, the different types of Low-E glass, the benefits of these different types, and the logistics you should consider when choosing a type of Low-E coating.

Key Takeaways:

  • Low-e is a type of energy efficient glass coating designed to reduce the amount of infrared and ultraviolet light that passes through the glass without compromising natural light
  • The razor-thin, transparent low-e coating reflects heat from the outside and helps maintain a consistent temperate inside
  • Low-e also helps reflect interior heat back inside the home, thus reducing energy costs
  • Low-e glass comes in two types: Passive or “Hard Coat” and Solar Control or “Soft-Coat”
  • Passive “Hard Coat” low-e glass works well for extremely cold climates

What is Energy Efficiency in a Home?

When we are talking about energy efficiency in a home, we are talking about lowering our energy consumption (so preserving more heat inside during the winter so we don’t run the heater so much, for example). We’re also thinking about greenhouse gas emissions and reducing our demands for nonrenewable resources. While providing for a healthier living condition, energy efficiency correspondingly should have a considerable benefit on your wallet because of reduced energy use and lower utility bills.

What about Energy Efficient Glass?

Now when discussing energy efficient glass, we are talking about a specific coating for glass that is either double or triple glazed that is designed to prevent heat from escaping through windows as well as stopping unwanted energy/heat from entering the home. Arguably the most known variant of this type of glass is low-emissivity glass, or low-e glass.

What is Low-E Glass then?

Low-E is energy efficient glass designed to reduce as much as possible the amount of infrared and ultraviolet light that escapes through glass but does not reduce the amount of light that enters your home. A razor-thin, non-toxic coating covers this glass that, while transparent, reflects heat. This glazing also helps maintain a consistent temperature in your home by reflecting interior temperatures of your home back inside.

The Benefits of Low-E Glass

First, low-e windows reduce energy costs. By blocking infrared light from entering the home, these windows keep unwanted heat out. Alternatively, by reflecting interior heat back into the home, this helps keep in your heating and cooling energy. Therefore, you don’t have to run your heating and cooling systems as much, helping to keep your utility bills low.

Second, these coatings help reduce destructive ultraviolet (UV) light rays. UV light fades colors on fabric in the home, so low-e glass helps maintain your carpets, furniture, drapes, and floors from fading and sun damage. Low-e windows even protect your skin just like sunscreen.

Lastly, low-e coatings do not block all natural light. While some natural light is blocked along with unwanted UV and infrared rays, enough natural light passes through to help brighten up any room.

If energy efficiency is a top priority in your home, these benefits of low-e glass that are not offered by windows without this coating can’t be ignored in your next home renovation.

How is Low-E Glass Made?

There are two types of low-e glass – passive and solar control – and both are made differently.

Passive Low-E Coating or “Hard Coat”

Using what is known as the pyrolytic process, the heating of an object with absence of oxygen, this type of low-e glass comes out as a pyrolytic coating. Next, this coating is layered onto a glass as it moves along the float line. The result is that the coating fuses to the hot glass surface, creating a strong, highly durable bond, or hard coat.

Solar Control Low-E or “Soft-Coat”

Soft coat low-e glass is formed using what is known as magnetron sputtering vapor deposition, where the coating is added off the float line to a pre-cut glass in a room temperature vacuum chamber. This coat must be sealed in a laminated unit/insulated glass. The benefit is, however, that this coating achieves lower emissivity and greater solar control.

Which Type of Low-E Glass Works Best for your Home?

Regarding which type of low-e glass to use, a big factor you’ll need to consider is climate. If you live in an extremely cold climate, you’ll definitely want to consider a hard coat. The reasoning here is that hard coat allows for short-wave infrared energy to pass through, naturally heating your house during the cold while reflecting heat inside the house back into it.

For most houses in the United States, however, that do not rest in extremely cold temperatures, soft coat low-e glass simply offers better UV protection and does not allow as much energy loss from your heating and cooling systems.

Alternatives to Low-E Glass

While there is no catch-all, better glass coating currently available, there are different avenues to help improve the energy efficiency of your windows.

Insulated coating consists of two or more panes of glass spaced apart and hermetically sealed, leaving an insulated air space. This lowers the amount of heat loss, but more UV and infrared rays can pass through.

Spectrally selective coatings are specific types of low-e glass that reflect wavelengths while remaining transparent to others. Thus, infrared light is reflected while visible light is admitted.

Gas fills and spacers are also used to lower heat transfer between windows. Argon and krypton are gases commonly used as they are nontoxic, odorless, and clear. Spacers help keep the layers of coating the correct distance apart. They also provide for thermal expansion, pressure differences, and prevention of gas and moisture leaks.

Also think about the type of window you are using and how it operates, as some operating types account for less air leakage. For example, awning windows typically have lower air leakage rates in comparison to sliding windows.

Finally, consider the type of frames you will use for your windows when thinking about heat and energy efficiency. While there are benefits and drawbacks to all types of frames, fiberglass, wood, vinyl, and composite frames provide better heat resistance than metal.

AVI Has Got You Covered!

Whatever type of window installation/replacement you are thinking about doing for your next home renovation, the folks at AVI are here to help. We’ll help you go through all of your low-e glass options and considerations. With our online and in person services, we’re your one stop shop to view, choose, and install the perfect windows for your home.

Please don’t hesitate to reach out to us online, by phone, or at one of our southeast locations. We’re here and ready to help!

Interested in learning about other energy efficient window types?