Energy Efficient Glass
All window glass may look the same. But not all glass performs the same. Every Renewal by Andersen window comes standard with High-Performance™ Low-E4™ glass. While you can't see the differences in glass, you will appreciate them. Compared to ordinary dual-pane glass, High-Performance Low-E4 glass is 35% more energy efficient in winter and 41% more efficient in summer.*
High-Performance Low-E4 glass also features an invisible titanium dioxide (TiO²) coating on the exterior glass surface that makes cleaning easier. When activated by sunlight, the coating loosens dirt from the glass so it can be washed away by rain. And it makes the exterior glass surface dry faster with up to 99% fewer water spots.** Our glass is even protected on both sides by a removable film that helps shield it from damage. When it comes to energy efficiency, this type of glass, or glazing, stands head and shoulders above single pane or ordinary double pane glass. There are Five Key Components to energy efficient glass. Details make all the difference in long term performance.
1. Argon gas blend - Manufacturers first started using double glazing back in the 1950s. At first, manufacturers used only air between the panes, and many still do. Manufacturers of better double-pane glass products fill the space with an inert argon gas which improves its energy efficiency by 30%. Renewal by Andersen uses a special blend of argon and other gases which helps preserve the integrity of the air space over time to optimize performance.
2. Glass coatings - Andersen® High-Performance™ Low-E4TM glass has a total of eleven metallic coatings. On the exterior, two coatings are applied to help make cleaning easier. Nine additional low emission coatings are bonded to the inside surface of the exterior pane of glass. The nine Low-E coatings are made up of microscopic metallic layers which restrict the flow of radiant heat across the sealed space between the panes of glass. Low-E coating bounces the heat back where it comes from. In winter, that means your heat stays inside. In summer, heat from the sun gets bounced back outside. High-Performance Low-E4 glass also cuts UV transmission down to 17%, which helps reduce fading of your carpet, drapes and furniture.
The Andersen coating process is sometimes referred to as a soft coat or sputter coat. The sputter coat gives the best coverage with little effect to the color of the glass or its transmission of visible light. Some manufacturers use pyrolytic coatings, or hard coats, which are applied to hot glass. The hard coat is durable, but the quality of the glass suffers—the color and consistency of the glass declines, and it can appear hazy. Other manufacturers use an e-coating applied to a sheet of plastic film that is then suspended between the two panes of glass. When the plastic film heats up from the sun, the plastic changes—the heat can causes the plastic to emit a gas which can discolor or haze the glass.
3. Spacer - Renewal by Andersen uses a low-conductivity spacer made of stainless steel that resists heat transfer 4-5 times better than aluminum spacers used by many other manufacturers. Also, because stainless steel is so much stronger than aluminum, our stainless steel spacer can use less material and still keep the glass stable. An inferior spacer may allow the glass to move, thus breaking its seal. Some window manufacturers even use plastic for their spacers. Plastic can deteriorate over time, causing a seal failure. Plastic spacers can emit a gas when heated by the sun, which can cause a chemical fog between the two panes of glass and affect visibility.
4. Double glazing - Two panes are better than one pane. But the space between the glass needs to be calculated for optimal thermal performance. When there is not enough space between the two panes of glass, the two panes act more like one pane—not as energy efficient. If the two panes of glass are too far apart, heat changes the convection currents within the space, which boosts the heat transfer instead of preventing heat transfer. Renewal by Andersen spaces the two glass panes for the best thermal performance.
Why not triple glazing? Triple-pane windows have lost popularity due to higher seal failure rates. The extra layer of glass adds significantly to weight while only marginally improving the efficiency. The sash and frame need to be thicker and heavier to support the extra weight. This makes the area of the glass—and the amount of light the window lets in—smaller. The added weight also places additional stress on the window hardware.
Today’s double panes, especially those with low-E coatings, improve a window’s energy efficiency without the added weight and structure. Renewal by Andersen® windows provide excellent energy efficiency while still providing exceptional window beauty. The sash and frame profiles look good in your home and deliver better glass-to-frame ratios (more glass/less frame) than many other replacement windows.
5. Dual Seal - The insulating glass in Renewal by Andersen windows is secured with two sealants: a compressed butyl and a specially formulated silicone. We also remove the Low-E coating around the embedded glass edge to make sure the sealant has a clean surface to adhere to. Other manufacturers leave the coating around the edge which can contribute to seal failure. Our precise sealing process helps provide a longer life for the windows, helping to prevent moisture from leaking in between the double glazing, and preventing the argon gas blend from leaking out. After 20 years, your Renewal by Andersen® windows will still provide better insulation than most other brands.* The chart below documents failure rates of glazing sealants in a study done by the Sealed Insulating Glass Manufacturers Association. Renewal by Andersen has significantly lower seal failure rates than industry standards. In fact, our glass is in a class of its own. That’s real value!
* 35% more energy efficient in winter and 41% in summer, as compared to ordinary dual pane glass.
** On exterior surface when activated by sunlight.