Today’s window industry has a lot more to offer than the classic single glass pane. Modern window glazing incorporates multiple panes, gas fillings, and high-tech coatings, which are all great for energy efficiency and saving money. However, the wide variety of options can be difficult to navigate. This guide will explore the various types of window glazing, their benefits, and how to choose the right option for your needs.
What Is Window Glazing?
Window glazing refers to the glass features used in windows. This plays an impactful role in your home’s energy efficiency, comfort, and overall appearance. Modern glazing systems do more than just let light in—they help regulate temperature, block harmful UV rays, and reduce outside noise. The right glazing can significantly impact your home’s energy consumption, potentially leading to substantial savings on heating and cooling costs.
Types of Window Glass
Window glass technology has evolved significantly over the years, offering homeowners increasingly efficient options.
Single-Pane Windows
Single-pane windows, which used to be the standard, are made up of just one layer of glass. They’re not energy efficient and offer little protection against heat or cold. They’re rarely used in new construction due to their poor insulating properties. However, if you have an older home with single-pane windows, you can improve their efficiency by adding storm panels or upgrading to modern, energy-efficient windows.
Double-Pane Insulated Glass
Double-pane insulated glass, also known as dual-pane or insulated glass units (IGUs), is the most common type of window glazing in modern homes. These windows feature two panes of glass with a layer of nontoxic, inert gas—typically argon or krypton—sealed between them (more on this below). The gas acts as an insulator, slowing heat transfer and improving energy efficiency. Double-pane windows eliminate the need for storm windows and provide better insulation than single-pane options.
Argon Gas Filling
Argon gas is a popular choice for enhancing efficiency in double- and triple-pane windows. Argon, an inert gas, is denser than air, which helps to reduce the transfer of heat between the interior and exterior of a building. By filling the space between the panes with argon, these windows significantly improve insulation compared to air-filled windows. Argon-filled windows are widely used in residential and commercial buildings to lower heating and cooling costs, making them a cost-effective solution for improving thermal performance.
Krypton Gas Filling
Krypton gas offers superior insulation for high-performance windows. Krypton is denser than argon, providing even better thermal resistance, making it an excellent choice for narrow spaces between panes. Although more expensive, krypton-filled windows deliver exceptional energy efficiency, making them ideal for regions with extreme temperatures. These windows are often found in premium residential and commercial applications that prioritize maximum energy savings and comfort. Krypton-filled windows are a significant upgrade over standard double-pane windows.
Triple-Pane Insulated Glass
If you want maximum energy efficiency, triple-pane windows offer a third layer of insulation. These windows contain three panes of glass with two gas-filled spaces between them. While they provide excellent performance in extreme climates and can significantly reduce sound transmission, triple-pane windows are heavier and more expensive than double-pane.
Advanced Glazing Technologies
As window technology continues to advance, new glazing options offer even greater energy efficiency and performance. Two notable advancements are low-emissivity (low-e) coatings and heat mirror technology.
Low-Emissivity Coatings
Low-e coatings are thin, invisible layers of metallic oxide applied to window glass. These coatings reduce the amount of heat that passes through the glass, improving energy efficiency. Low-e coatings can be tailored to either allow or block solar heat gain, making them customizable for either hot or cold climates.
“The extra cost is minimal, and it’s really beneficial in the long run,” says Tom Silva, pointing out that, because low-e coatings also filter ultraviolet radiation, they protect furniture, rugs, and artwork from fading.
While low-e coatings add about 10%–15% to the cost of a window, they can reduce energy expenditures by approximately 30%–50% compared to plain insulated glass, according to the Department of Energy.
Heat Mirror Technology
Heat mirror technology takes window insulation to the next level. This system suspends a sheet of low-e film between panes of insulated glass, matching or even exceeding the energy efficiency of triple-pane windows without the extra weight. Some advanced systems, such as Superglass, use two layers of heat mirror film between glass panes with gas-filled spacers, offering superior insulation.
Tinted/Reflective Glass
Tinted or reflective glass is designed to reduce glare and control solar heat gain, making it an excellent option for sunny climates. These windows feature a special coating or tint that minimizes the amount of heat and UV rays entering a building. By blocking excessive sunlight, tinted or reflective glass helps maintain a comfortable indoor temperature and reduces the reliance on air conditioning. These windows are particularly beneficial for office buildings and homes in hot regions, offering significant energy savings and protecting interior furnishings from sun damage.
Smart Glass
Smart glass, also known as electrochromic or photochromic glass dynamically changes its light transmission properties. These windows can adjust from clear to tinted in response to an electric current or sunlight, providing optimal control over light and heat levels. Smart glass helps reduce energy consumption by minimizing the need for artificial lighting and managing solar heat gain. This technology is ideal for modern buildings seeking energy efficiency and advanced functionality, offering substantial energy savings and enhanced comfort throughout the day.
Vacuum Glazing
Vacuum glazing is a cutting-edge technology that provides exceptional insulation by creating a vacuum between two panes of glass. This vacuum eliminates the conduction and convection of heat, resulting in extremely high thermal resistance. Vacuum-glazed windows are among the most energy-efficient options available, significantly reducing heat transfer and energy costs. They are ideal for use in both residential and commercial buildings, particularly in regions with harsh climates. Despite their higher initial cost, vacuum glazing offers long-term savings and superior comfort.
How To Choose the Right Glazing
Selecting the right glazing for your home means learning about energy efficiency ratings and your local climate.
Evaluating Energy Efficiency Ratings
When shopping for new windows, look for the National Fenestration Rating Council (NFRC) label. This label provides information on the window’s energy performance in three key areas:
- U-factor: Measures how well the window insulates (lower is better)
- Solar Heat Gain Coefficient (SHGC): Indicates how much solar radiation passes through the window (lower means less heat gain)
- Visible Transmittance (VT): Shows how much light the window lets in
The Energy Star program simplifies the selection process by certifying windows that meet minimum efficiency standards for specific regions. Energy Star windows typically exceed building code requirements. While they often cost more than non-certified options, you’ll likely make your investment back and then some given how energy-efficient they are.
Considering Your Climate and Orientation
Your local climate and the orientation of your windows play a role in choosing the right glazing. In cold climates, you want windows with a lower U-factor and higher SHGC to maximize heat retention. In warmer regions, look for windows with a lower SHGC to minimize heat gain. Consider the direction your windows face as well—south-facing windows benefit from different glazing than north-facing ones.
Reglazing Windows
Reglazing is the process of replacing the glass in existing window frames. This process can improve energy efficiency without the need for full window replacement.
DIY Window Reglazing: Steps and Precautions
For those comfortable with DIY projects, reglazing can be a cost-effective way to improve window performance. Here’s a basic overview of the process:
- Remove the old glazing compound and glass.
- Clean the window frame.
- Apply new glazing points to secure the glass.
- Install the new glass pane.
- Apply a new glazing compound.
When To Call a Professional Glazier
While DIY reglazing is possible, it’s often best to hire a professional glazier, especially for large or detailed windows. Professional glaziers have the tools and expertise to ensure a proper seal and the best performance. They can also advise you on the best glazing options for your specific needs.
Cost of Glazing Windows
When considering window glazing options, balance initial costs with long-term savings.
Initial Investment vs. Long-Term Savings
While more advanced glazing systems such as triple-pane or heat mirror windows have higher upfront costs, they can lead to significant energy savings over time. Consider your budget, expected length of home ownership, and potential energy savings when making your decision.
Energy Star Windows
Energy Star-certified windows typically cost more but come with substantial energy savings. In many cases, ower utility bills offset the initial cost within a few years. Additionally, some utility companies and government programs offer rebates for Energy Star windows, further reducing overall cost.
| Type of Glazing | Energy Efficiency | Potential Energy Savings (Compared to single glazing)* |
| Double glazing | Moderate | 20%–30% |
| Triple glazing | High | 40%–50% |
| Low-e coatings | High | Additional 10%–15% over double/triple glazing |
| Gas fills (argon) | High | Additional 5%–10% over air-filled glazing |
| Gas fills (krypton) | Very high | Additional 10%–15% over air-filled glazing |
| Tinted/Reflective glass | Variable | 10%–20% cooling |
| Vacuum glazing | Very high | 50%–60% |
| Smart glass | High | 20%–30% |
Maintenance and Care for Glazed Windows
Proper maintenance can extend the life and performance of your glazed windows.
Cleaning Techniques for Different Glazing Types
Clean your windows regularly using a mild soap solution and a soft cloth. Avoid abrasive cleaners or tools that could scratch the glass or damage coatings. For windows with special coatings, follow the manufacturer’s cleaning instructions to maintain their performance.
Signs That Your Windows Need Reglazing
Watch for these signs that it may be time to reglaze your windows:
- Drafts around the window
- Condensation between panes in double or triple-glazed windows
- Cracked or chipped glass
- Peeling or cracking glazing compound
Addressing these issues promptly can prevent further damage and maintain your windows’ energy efficiency.