Heat loss through doors and windows makes up for about 30% of the heat lost in your entire home. Low-E glass is a modern innovation that helps cap down heat loss during winter and prevent heat entry during summer.

Low-grade glass is your go-to option if you are a homeowner searching for smart solutions and energy-efficient windows to solve your energy loss problems. By altering how window glasses transfer heat, low-E coatings help ensure the comfort of your home while saving on energy costs. This article captures what every homeowner ought to know about low-E glass.

The low-emissivity glass was designed to reduce the amount of ultraviolet and infrared light coming through your glass without affecting the amount of natural light reaching your room. Low-E glass windows have a thin transparent coating that reflects light. These coatings maintain the consistency of internal temperatures by reflecting interior temperatures inside.

What a Low-E Glass Window Is

Low-E stands for low emissivity. Low-E windows have glass coated in invisible metallic oxide layers. The coating allows the entry of natural light into your home and, at the same time, deflects infrared light and UV rays out to the environment. So, why is this important?

Ultraviolet rays are the invisible light rays that the sun emits. These rays damage building materials, burn kin and cause upholstery to fade. On the other hand, infrared light is the heat that brings warmth to your home during winter. By deflecting these types of light to the environment, low-E coatings ensure your house stays cool during summer and warm during winter.

Some of the factors used to establish the effectiveness of low-E glass coatings include:

· U-Value: The rating given on a window depending on the amount of heat loss it allows

· Light to solar gain: the ratio between a window's visible light transmittance and its Solar Gain Coefficient rating

· Visible Light Transmittance: the measure of how much visible light traverses the glass

· Solar Heat Gain Coefficient (SHGC): The portion of incident solar radiation that the window admits.

Types of Low-E Coatings

There are two types of low-E coatings:

· Passive Low-E Coatings: These coatings are manufactured using the pyrolytic process to form a pyrolytic coating. The resulting coating is then applied to the glass ribbon as it is produced by the float line. This causes the fusing of the layer to the hot glass surface. The fusion creates a durable, strong bond.

· Solar Control Low-E Coatings: these are also known as soft-coat coatings. The coatings are manufactured using the Magnetron Sputtering Vapor Deposition (MSVD) process. This means that the coating is applied offline to precut glass in a vacuum at room temperature. Besides having lower emissivity, the soft coat has superior solar control performance.

Which Type of Low-E Coating Is the Best?

Before choosing a low-E glass, you should consider your area's climate. For example, if your area is extremely cold, you might want to consider getting the hard coat low-E glass. This is because it allows the entry of the sun's infrared energy. As a result, your home stays warm during winter.

However, if your area's climate ranges from cold to hot, soft-coat low-E glass is the way to go. Why? It offers better protection from UV rays. In addition, it has a better overall U-value. Also, instead of allowing warm, cool air to leak to the outside, the soft-coat coating reflects it to your room.

How Does It Work and Make Windows Energy Efficient?

At first, if you hear about the working of low-E glass, you may find it difficult to believe how glass can control the entry and exit of light in your home.

While low-E coatings aren't openly visible, they are still reflective. Look at it like the silver lining in a thermos. When the thermos has hot contents, the heat bounces off this lining before reflecting inside to ensure the contents remain warm. This can be compared to the heat inside your house in the cool winters. The reverse is true. When the thermos has cold items, heat does not penetrate via the silver lining. Therefore, the heat on the outside bounces or reflects off the low-E glass window during summer, leaving your home cooler and reducing your energy bills.

How to Lower Your Energy Bills

Low-E glass helps reduce energy costs by reducing the amount of heat leaving and entering your home in winter or summer. In summer, low-E glass shuts away hot air from your home, while in winter, it traps warm air in, helping reduce your furnace heating costs.

Does My House Have Low E Glass?

Are you wondering whether your house could have low-E glass windows? If it isn't old, there is a possibility that it could have these windows. Here are steps to follow to find out if your windows are low-E glass:

· Hold a lighter or match in front of your window

· Spot the image of the four flames that will reflect in the glass

· In the case of low-E glass windows, one of the images will have a different coloration from the rest

· If your window isn’t low-E glass, all the images will be similar in color

Will Low-E Glass Increase the Cost of Replacement Windows?

Yes, it will. Because low-E windows involve a lot of labor and technology, you will incur more costs than standard windows. However, this shouldn't scare you as in the long run, you are guaranteed significant savings. With low-E coatings, you can reduce as much as 50% energy loss resulting from heat conduction. Simply put, if you install low-E windows on your property, you can get back the money spent.

Besides reducing energy costs in your home, the windows significantly reduce the replacement and maintenance costs associated with flooring materials and furnishings. Also, by making it easier to cool and heat your house, low-E windows relieve your home's HVAC system.


Installing low-E windows will help save on costs in different ways. Keep such cost savings in mind as you try to establish whether this window type is worth the hassle.

September 02, 2022 — Della Wang