Energy-efficient windows are an excellent way to minimize your heating and cooling costs, but how do these windows really work? When it comes to windows, the type of glass is always a crucial consideration because it’s the biggest component of a unit. In fact, according to experts, as much as 70% of energy loss occurs due to inefficient windows and doors, and that 90% of heat loss in windows can be attributed to a unit’s glass package. Energy efficiency remains one of the most important factors when upgrading windows, but the lingo can be challenging when researching various types of energyefficient glass. Here, you’ll be learning all about lowemissivity (low-E) glass, why it’s energy-efficient and what sets it apart from traditional glass options, as well as answers to some of the most common questions about this type of window glass.
PART 1:
What is Low-Emissivity Glass and How Does it Work? Getting energy-efficient windows is among the essentials when undergoing home improvement. Over time, windows have improved quite significantly, not just in beauty and durability, but also in thermal performance. One of the innovations homeowners can enjoy today is low-emissivity, or low-E, glass. What is this glass type exactly and how does it actually work? Let’s find out. THE DIFFERENT KINDS OF LIGHT The solar energy spectrum can be divided into three categories: ultraviolet light, visible light, and infrared light. Ultraviolet (UV) light can be damaging—in fact, it’s responsible for interior fading, dulling
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the appearance of carpeting, furniture, walls, and others inside the home. Visible light, on the other hand, is the light that you see with your own eyes. You see it shining down from the sun, enveloping your home exterior before making its way indoors through your windows. Its counterpart is infrared light, or the invisible light. Although you can’t see it, you can feel it on your skin as heat. Aside from the sun, other warm objects also emit significant amounts of infrared light. UNDERSTANDING HOW LOW-E GLASS WORKS Most of the time, people don’t want to block visible light coming through the window, but it would be helpful to regulate, if not completely block UV and infrared lights. Low-E glass is designed to serve this specific purpose.
With the help of a special coating, low-E glass reduces the amount of UV and infrared light that can pass through a window without compromising how much visible light is let in. These coatings work by adding a microscopically thin layer of metallic oxide to the glass, which reflect unwanted light and heat away from the surface. They can be applied to either interior- and exterior-facing sides of window glass, reflecting the indoor heat back inside while keeping excess heat out of the home.
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There are several factors used to measure the effectiveness of low-E windows and generally other energy-efficient replacement units. With their ratings found on labels provided by the National Fenestration Rating Council, these include: SOLAR HEAT GAIN COEFFICIENT - This refers to the amount of solar heat allowed to enter the window. The lower the rating, the better. U-FACTOR - This measures how much heat loss a window allows. The lower the rating, the better. VISIBLE TRANSMITTANCE - This indicates how much visible light passes through the glass. The higher the rating, the better. AIR LEAKAGE - This signifies how much air can enter a room through a window. The lower the rating, the better.
How does low-emissivity glass differ from other window glass types? What are its notable advantages? Find out in Part 2 of this ebook!
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PART 2:
Advantages of Low-Emissivity Glass over Traditional Options
When it comes to building materials, glass stands unique because of its absolute versatility. Aside from letting light through, it also helps regulate thermal performance, which is crucial to ensuring comfort and energy savings for your home. You can boost these benefits even more through the use of low-emissivity (low-E) glass, which offers the following advantages over standard glass types: HELPS PRESERVE YOUR WINDOW’S LOOK AND PERFORMANCE. The specialized coating that covers the surface of your window glass is the key component of low-E glass. Microscopically thin and transparent, it adds another layer of protection against micro-abrasive materials, such as sand, dirt, and dust. As a result,
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your windows remain clear and whole for a long period. In addition, this coating helps block water particles from sticking to the surface, making it easier for you to maintain your windows and keep it looking attractive for years. PROTECTS YOUR HOME’S INTERIOR FROM FADING. Unlike standard glass types, low-E glass can help block unwanted rays coming from UV light. This prevents fading and deterioration in a range of furnishings, including carpets and fabrics. However, you don’t have to worry about dim spaces with low-E glass as interior protection doesn’t come at the expense of visible light, allowing you to make sure your living spaces remain bright all the time. HELPS YOU SAVE MONEY. Having windows that feature Low-E glass can assure you of bigger energy savings in the long run. Since it helps filter out infrared light, which is mainly responsible for heat transmission, you can minimize your reliance on artificial cooling systems, leading to savings on your energy bill. On the contrary, standard glass options are unable to keep infrared rays at bay, leaving your home vulnerable to unwanted passive heating and higher energy bills.
Got questions about low-E glass? In Part 3 of this ebook, we’ll be covering some of the common questions about low-E glass, providing the answers you might be looking for about this type of window glass. Stay tuned!
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PART 3:
Frequently Asked Questions About Low-Emissivity Glass
Is it possible to buy replacement windows that pay for themselves over time? This is a question many homeowners ask when shopping for new windows. The term you’ll often hear associated with energy efficiency is low-emissivity (low-E) glass, which provides great energy savings by keeping indoor heat in and outdoor heat out. If you’re a homeowner looking to purchase energy-efficient windows soon, you should familiarize yourself with these technologies so you can make informed decisions. Here, we answer some of the common questions regarding low-E glass, such as: HOW DOES LOW-E GLASS WORK IN SUMMER? Low-E glass not only prevents heat loss during winter; it also reflects UV and infrared rays out during summer.
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In a nutshell, the glazing rejects certain portions of the light spectrum, only allowing a fraction of these rays to enter a home. As a result, excessive heat gain is prevented, allowing you to keep indoor spaces cool with less effort. This means you don’t overwork your cooling systems during the warmer months because low-E glass helps regulate your interior atmosphere all season long. IS THERE A PARTICULAR TYPE OF LOW-E GLASS COATING SUITABLE FOR MY LOCAL CLIMATE? There are two basic types of low-E coatings—passive (hard-coat) and solar control (soft-coat). Before deciding which type of low-E glass is best for you, it’s paramount to consider your area’s climate. For those living in an extremely cold climates, hard-coat low-E glass is ideal for you, as it allows a portion of the sun’s short wave infrared ray to pass through the glass. This helps keep your interior warm during winter thanks to passive heating.
If you live in an area that experiences cold and hot conditions, however, it’s best to use soft-coat low-E glass. It offers superior UV protection and has a better U-factor in general, keeping indoor heat in and outdoor heat out to stabilize indoor temperature.
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IS LOW-E GLASS DARKER COMPARED TO STANDARD GLASS? Not necessarily. low-E glass’ coating is microscopically thin that it’s not visible to the human eye. This means nothing stands in the way of illuminating your indoor living spaces, keeping them as bright and airy as you want while minimizing radiant heat.
Low-E windows are a long-term solution for keeping your home comfortable throughout the seasons, all while keeping your furnishings safe from damage and reducing your monthly bills. To be sure that a window is truly energyefficient, look for the ENERGY STAR® label—this indicates that your new units have met standards set by the U.S. Department of Energy. To learn more about low-E glass, don’t hesitate to get in touch with a reputable window contractor in your area.
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RENEWAL BY ANDERSEN OF GREATER PHILADELPHIA 761 5th Ave #3, King of Prussia, PA 19406
(610) 813-6777
www.choosebetterwindows.com