Why Aren’t Single Pane Windows Used Anymore?

Why Aren’t Single Pane Windows Used Anymore?

May 13, 2024
Martin Whitmore, President of US Window & Door
Photo of an old single-pane window with condensation in the glass.

Single-pane windows have largely fallen out of favor in modern construction. While there is evidence of glass windows for centuries, glass wasn't commonly used in home windows until around the 17th century in Britain because other basic coverings like paper or animal hide, depending on the culture, were more economical before modern manufacturing techniques. As their name suggests, single-glaze windows consist of a single layer of glass in a frame, providing only a basic barrier against the elements. While they were widely used for many years due to their simplicity and low cost, single-pane windows have been largely replaced by more advanced and efficient options like double and triple-pane windows.

Single-pane windows were primarily replaced due to their poor energy efficiency, lack of soundproofing, and susceptibility to condensation and moisture issues. As building codes have become more stringent and homeowners have sought ways to reduce energy costs and improve comfort, double and triple-pane windows have become the preferred choice for new construction and replacement windows.

To learn more about why single-pane windows aren't used anymore, we'll explore the disadvantages of old single-pane windows and discuss why double-pane and triple-pane windows have become the new standard. We'll also delve into the differences between single, double, and triple-pane windows to help you understand the benefits of upgrading your home's windows.

Disadvantages of Old Single-Pane Windows

While single-pane windows were once the standard in homes, they have several significant drawbacks compared to modern double- and triple-pane windows. These disadvantages can lead to increased energy costs, moisture issues, and reduced comfort in your home. If you still have old single-pane windows, it's time to speak to a professional about replacing them to avoid the issues outlined below. 

Poor Energy Efficiency

Single-pane windows are poor insulators, allowing heat to easily transfer in and out. During the winter, warm air from inside your home can quickly escape through the single layer of glass, while cold outdoor air can seep in. In the summer, the opposite occurs, with hot outdoor air entering your home and cooled indoor air escaping. This leads to increased heating and cooling costs compared to double or triple-pane windows. Your HVAC system has to work harder to maintain a comfortable temperature, leading to increased energy consumption and higher utility bills.

Modern windows support natural energy efficiency by better locking in the home's interior temperature. With dual-pane and triple-pane windows, your HVAC systems will turn on less often and run for less time than with single-pane windows because of the improvement in insulation, assuming there are no other issues with your home's insulation unrelated to the windows.

Condensation and Moisture Issues

Single-pane windows are prone to condensation buildup on the interior side of the glass. When humid warm indoor air contacts the cold glass surface, moisture condenses and accumulates on the window. Moisture can drip down and damage window frames, walls, and floors, potentially leading to mold growth. Over time, this excess moisture can cause wood to rot, paint to peel, and drywall to deteriorate, leading to costly repairs. 

Newer windows are built to mitigate these issues by channeling condensation through the tracks and outside the home or normalizing the environment on the windows as the sun rises to turn condensation back into humid air. Single-pane windows were often made of wood or aluminum, which can rot or corrode from this moisture; however, newer windows are made from materials less susceptible to condensation damage, such as vinyl and fiberglass

Lack of Soundproofing 

With only one pane of glass, old single-pane windows allow more outside noise compared to double or triple-pane windows. Traffic, neighbors, and other external sounds can easily penetrate through a single layer of glass, disrupting the peace and quiet of your home. The lack of an insulating air space between panes means that sound waves can travel through the window more efficiently, leading to a noisier indoor environment. 

Upgrading to double or triple-pane windows with thicker glass and insulating air spaces can significantly reduce outside noise infiltration. However, it's important to note that some frequencies, especially lower frequencies, can still enter a home through the walls. Lower-frequency sounds pass through other materials more easily, so even with the newest windows, they may not block all sound. Regardless, compared to single-pane windows, you will surely enjoy a more peaceful environment due to some measure of sound reduction with dual-pane or triple-pane windows.

Why Double-Pane Windows are Better

Photo of a dining room with white vinyl double-pane windows

Double-pane windows offer several advantages over traditional single-pane windows. The additional pane of glass and the insulating air space between the panes improve energy efficiency, reduce condensation, and enhance soundproofing compared to single-pane windows.

Improved Energy Efficiency

Double-pane windows provide better insulation with the additional pane of glass and insulating air space. The extra layer of glass and the trapped air or gas between the panes act as a barrier, slowing the heat transfer between the inside and outside of your home. This leads to more consistent indoor temperatures and lower energy bills compared to single-pane windows. Your HVAC system won't have to work so hard to achieve a comfortable temperature, reducing energy usage and creating savings on your utility bills.

Reduced Condensation

Insulating properties of dual-pane windows help prevent condensation from forming compared to single pane. Condensation builds when warm air comes into contact with a cold surface. In single-pane windows, the interior glass can get cold enough to cause moisture to condense inside the window. With double-pane windows, the insulating air space keeps the inner pane at a warmer temperature, reducing the chance that condensation forms. This helps prevent moisture damage to window frames, walls, and floors around the windows.

However, it's important to note that condensation is still possible and is most often seen on the interior of the glass. Some homeowners grow concerned when they first see that assuming the insulating glass unit wasn't properly sealed. However, this is normal and should disappear as the day heats up. If a homeowner is seeing consistent condensation or condensation that doesn't go away over a few days regardless of outside temperature, they should reach out to their installation company or the manufacturer to make sure the windows don't need repairs.

Enhanced Soundproofing

The extra pane of glass and air space in double pane windows helps block more outside noise than single pane windows. Sound waves have a more challenging time penetrating through two panes of glass and the insulating layer between them. While double-pane windows won't completely soundproof a room, they significantly reduce the noise entering your home from outside compared to single-pane windows. This is especially beneficial if you live in a busy urban area or near a highway, airport, or construction zone. Keep in mind that low-frequency noises are less likely to be improved simply by replacing the windows.

Ask About Milgard's 4th Surface Coating for Improving U-factor for Dual-Pane Windows

To help improve the U-factor for dual pane windows to increase performance, Milgard has created a durable TCO (Transparent Conductive Oxide) coating. Their goal was to improve energy efficiency of dual-glazed windows to achieve a triple-glazed window efficiency as they phased out triple-pane product offerings. While this coating won't further improve sound reduction, energy efficiency improvements are attainable. If energy efficiency improvements are vital to your projects and you want the best possible results, inquire about this specialized product option. However, make sure to ask your salesperson if this product is suitable for achieving your desired temperature and energy efficiency goals, as it may not be necessary or the best selection under all conditions.

Why Triple Pane Windows are Even Better But Likely Unnecessary

While double-pane windows provide significant improvements over single-pane windows for energy efficiency, soundproofing, and comfort, triple-pane windows go even further with three panes of glass and two insulating air spaces between them. Each additional pane of glass increases the window's energy efficiency, soundproofing capabilities, and overall strength. Adding a third pane of glass and a second insulating air space makes triple-pane windows the ultimate choice for homeowners seeking maximum performance. 

However, these benefits come at a higher cost compared to windows with fewer panes. The extra layers of glass and the specialized manufacturing process contribute to the increased price point of triple-pane windows. Because of the higher costs, these types of windows are most often found in areas with extreme temperature conditions and are more commonly used further north to combat extreme cold. 

With the generally temperate weather for San Diego County and peaceful neighborhoods, it's unlikely the extra cost for triple-pane windows would be worth the investment. If noise reduction is your goal, triple-pane can certainly help; however, as mentioned previously, low-frequency noises tend to permeate walls and may still create issues in the home, even with new windows, regardless of the number of panes. The noise reduction available from Dual-pane windows compared to single-pane windows is sure to be a solid benefit of switching to new windows.

Milgard's Energy-Efficient Window Options

US Window & Door proudly offers Milgard's double-pane window solutions to our customers. Milgard's innovative window technologies provide exceptional energy efficiency without compromising style or functionality. While Milgard doesn't offer triple-pane windows at this time, Milgard's double-pane windows come standard with advanced features that further enhance their insulating properties. These include:

- SunCoat® and SunCoatMAX® Low-E glass coatings that reflect heat and UV rays

- EdgeGardMAX™ spacers that reduce heat transfer and improve the window's structural integrity

- Optional argon and krypton gas fills between the panes for superior insulation

By combining multiple panes of glass with these state-of-the-art components, Milgard's windows minimize heat loss in winter and heat gain in summer. This leads to more consistent indoor temperatures, increased comfort, and potentially lower energy bills for homeowners.

Milgard offers its energy-efficient double-pane glass packages across its various window lines, including the Ultra™, WoodClad™, Tuscany®, and Essence™ series, allowing customers to choose the perfect style and material to complement their home's architecture without sacrificing performance.

When you choose US Window & Door to install Milgard's double-pane windows in your home, you can trust that you're getting the best in energy efficiency, durability, and craftsmanship. Our experienced team will work with you to select the ideal windows for your needs and budget.

Photo of large, energy efficient picture windows in a living room.

Making Windows Modern

In conclusion, single-pane windows were once the standard in home construction but have largely been replaced by double- and triple-pane windows in recent years. While single-pane windows have some advantages, such as lower upfront costs and the ability to maintain a home's classic aesthetic, they come with significant drawbacks.

Single-pane windows are poor insulators, allowing heat to easily transfer in and out, leading to higher energy bills and reduced comfort. They are also prone to condensation and moisture issues, which can cause damage to window frames, walls, and floors. Additionally, single-pane windows offer little soundproofing, allowing outside noise to easily penetrate the home.

In contrast, double and triple-pane windows provide superior energy efficiency, reduced condensation, enhanced soundproofing, and increased home value. While they may have a higher initial cost, the long-term energy savings and improved comfort often justify the investment.

Ultimately, the decision to replace single-pane windows with modern multi-pane windows depends on factors such as climate, noise levels, energy costs, and the home's age and architectural style. However, for most homeowners, upgrading to double—or triple-pane windows offers significant benefits that can improve their homes' comfort, efficiency, and value for years.