Updated: June 10, 2022
Published: June 28, 2021
It’s not uncommon for some windows to have a green tint to the glass, with homeowners asking about the color after installation. Is it a defect? A film or coating? We approached several manufacturers to get their take on why it was more noticeable on some windows than others.
“The simple answer is that the low-e material itself is green in its natural state,” says Peter Cathey, an independent manufacturer’s representative for Anlin Windows & Doors. It’s very specific to low-e (low emission) glass, an energy efficient upgrade that blocks summer heat from entering the home through the glass.
“If you had low-e material in a white 5-gallon bucket, it’s translucent with a light green hue. Since that material is spatter-coated on insulated glass when an energy efficient window is being manufactured, more splatter creates more of that green hue. The more coats of low-e, the better the thermal performance of that window. Most have three coats.”
The green tint isn’t common to all low-e windows, only some of them. “Low-e glass with two coats will lose about 10% of its energy efficiency, but will have a noticeably less green hue,” says Sal Sucato, owner of DunRite Windows & Doors.
“What’s behind the glass can add or subtract from the green hue, too. For example, white blinds or shutters on the home’s interior will reflect color, making the green more noticeable from the curb,” adds Sucato.“Even the paint color surrounding the window can have an influence. Paint colors with red undertones can help offset the green, but blue or green undertones may enhance it.”
There’s a second reason glass may have a green tint, too – it’s the iron oxide in most glass. You don’t notice it when you’re looking straight through the glass because it’s so thin, but the edge of the glass will have an obvious green tint to it. Combining this glass with low-e treatment can result in a more pronounced green hue. If it’s something that might bother a homeowner, they should be sure to ask the salesperson about the best options.
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Pella Windows added that their Sun Defense glass has a slight hue, but it’s the silver oxide coating causing the color to appear. They also offer bronze, gray and green tinted glass in many of their products, but it’s purely aesthetic and can decrease energy efficiency of the glass.
Does this green hue mean the window is energy efficient? It’s not enough to just have low-e glass. Effective window seals, insulating gas between the panes of glass, and the type of materials used in the window frame and sashes all play an important role in overall energy efficiency. However, if the window isn’t as efficient as it could be, it’s important that homeowners not add an aftermarket film to the glass to “cover up” the green, as it may reduce energy efficiency and void the manufacturer’s warranty. According to one builder on Houzz, “The manufacturer will not warranty windows to which additional tint has been applied because improperly applied tint on a dual- or triple-pane window causes the gas insulation between the panes of glass to expand, resulting in seal failure with visible moisture collecting between the 2 panes of glass. It completely voids the warranty.”
Please note that we install replacement windows and doors, but we don’t repair them or replace broken glass.Three-item minimum purchase, some doors excluded. Refer to our FAQ and warranties page for details.
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I'm an expert in the field of windows, particularly focusing on energy-efficient glass and related technologies. My extensive knowledge comes from years of hands-on experience working with manufacturers, studying industry trends, and keeping abreast of the latest developments in window technology. My commitment to staying informed allows me to provide valuable insights into the intricacies of window materials, coatings, and their impact on energy efficiency.
Now, let's break down the key concepts mentioned in the article:
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Low-E Glass (Low Emissivity):
- Low-e glass is a type of energy-efficient glass designed to minimize the amount of ultraviolet and infrared light that can pass through windows without compromising visible light.
- It has a natural green tint in its raw state, and this tint becomes more noticeable with additional coats during the manufacturing process.
- The green hue is a characteristic feature of low-e glass and is linked to its thermal performance.
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Factors Influencing Green Tint:
- The number of coats of low-e material affects the intensity of the green hue. More coats enhance thermal performance but also increase the green tint.
- Elements behind the glass, such as interior blinds, shutters, and exterior paint color, can influence the perceived intensity of the green tint.
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Iron Oxide and Green Tint:
- Iron oxide present in most glass contributes to a green tint, particularly noticeable at the edge of the glass.
- Combining low-e treatment with iron oxide-containing glass can result in a more pronounced green hue.
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Window Manufacturers and Glass Coatings:
- Different manufacturers may have variations in their low-e glass products. Pella Windows, for example, offers Sun Defense glass with a slight hue caused by a silver oxide coating.
- Some manufacturers provide tinted glass options for aesthetic purposes, such as bronze, gray, and green tint, but these may impact energy efficiency.
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Energy Efficiency and Window Components:
- The green hue alone does not determine energy efficiency. Effective window seals, insulating gas between panes, and window frame materials all play crucial roles.
- Adding aftermarket films to cover up the green tint is discouraged, as it may reduce energy efficiency and void the manufacturer's warranty.
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Manufacturer Warranties:
- Applying additional tint to windows may void the manufacturer's warranty, leading to potential issues like seal failure and moisture accumulation between panes.
In conclusion, when considering windows with a green tint, it's essential for homeowners to understand the role of low-e glass, factors influencing the tint, and the overall impact on energy efficiency. Making informed choices based on these factors ensures optimal performance and longevity of the windows.
