What Is Low-E Glass And Why Do I Want It In My Windows?

So you’re looking for a way to save your skin, comfort level, and indoor furniture from the sun. What if there were an energy-efficient, aesthetically pleasing window that had the right amount of filter? We know something that will do the trick: low-emissivity (low-e) glass window coatings. Yes, it’s a mouthful. But low-emissivity coatings inside the glass of a window help let in the natural light you want while filtering out UV rays and the heat that comes with them. That sounds like a win-win to us, but what exactly is low-e glass? To start, let’s dive into the solar spectrum.  


When it comes to the solar spectrum, there are 3 different elements of sunlight we want to be aware of—ultraviolet (UV), visible, and infrared. Understanding the differences between these three and what each are capable of will help us understand why the type of glass in our windows matters. Let’s quickly go over what each of these does: 

  • Ultraviolet light: what causes sunburns, fading, etc.; the most intense of the 3 
  • Visible light: what allows us to see (why we can’t see at nighttime!) 
  • Infrared light: why we feel heat from the sun

Image of a window with the solar spectrum depicted by arrows to show how low-e glass works

“Spectrally selective” refers to the window glazing process of low-emissivity, or low-e, glass. Low-e coating allows for optimal natural light and minimal heat/UV rays. The process is selective of the solar spectrum it lets in, hence spectrally selective. When we refer to spectrally selective coatings, we are also referring to low-e glass, and vice versa. 


Now that we are on the same page about what low-emissivity glass is, we can break down the benefits of its presence in your windows:  

  • Energy Efficient: Due to its ability to filter out heat from the sun, low-e glass keeps your internal temperature at bay. In turn, your A/C and heat won’t have to work as hard to keep you cool or warm, resulting in less energy used. Not only does this feature save you from running your A/C extra high, but the nature of spectrally selective coatings also allows for a better balance between natural daylight (visible light) and your in-home lighting fixtures. That said, you won’t have to worry about keeping the lights on for longer than you need to because of the transparent nature of the glass! 
  • No More Discomfort: Speaking of keeping you cool and warm, spectrally selective coatings in your windows ensure your home stays as cold or as hot as you want it, no matter the temperature outside. That means you control the comfort level in your home—the way it should be! Along with comfort in temperature, low-e glass coating provides comfort on the eyes, thanks to its balance of visible light. Though window treatments, such as curtains, blinds, or drapes, may help mask the sunlight coming in, low-emissivity glass reduces the need to strain or squint your eyes as you look out into the yard.  
  • Cost-Friendly: Less energy = less money wasted. When your windows filter out unnecessary heat, you don’t have to worry about your A/C unit working overtime to keep you cool, resulting in lower electricity bills. Same thing goes for your light fixtures! Because of its ability to keep your home lit naturally, low-e glass keeps you from having your lighting fixtures on throughout the day, saving you more and more $$$. 
  • Easy On the Eyes: Not only does it feel better on the eyes, but spectrally selective coatings look better due to their transparent nature. No more tinted or reflective glass. You get the benefits of both with the aesthetics of a clear window. This is where visible light comes in. The microscopic layers in the coatings allow for an optimal amount of visible light to shine through, while keeping infrared and UV light at a minimum. Additionally, if you aren’t into the look of window treatments, low-e glass allows you to skip these in certain rooms, or altogether!
  • Protects Your Furniture: You’ve thought about UV rays harming your skin, but have you thought about UV rays harming your living room furniture? Whether you notice it or not, the lack of low-e coatings in your current windows are fading your favorite grey couch. The intense nature of UV light leaves your wood tables, antique rugs, plush sofas, etc. at risk of fading over time. Low-e glass reflects those harsh UV rays from the sun, leaving you with the peace of mind that your treasured pieces are protected. 

ChoosING the Right Energy-Efficient Features for Your Window 

Combined with frame material, insulating spacers, and other awesome features, low-e glass coatings leave you with an energy-efficient, comfortable, cost-friendly, aesthetically pleasing home. While it may seem daunting after learning all about the amazing benefits of low-e glass, it’s comforting to keep in mind the resources available to you as you pick out new windows for your home  

Energy-efficient replacement windows are a great way to save energy and save money. But the ideal design—one that’s both efficient  and  cost-effective—will depend on your home’s unique characteristics. Depending on the climate where you live, your lifestyle, and your overall wants and needs, deciding on the right windows (and any feature of your home for that matter) is made easier with an expert opinion. 

West Shore Home offers a free, expert consultation to explore a vast selection of energy-efficient replacement windows. Our trained, full-time remodelers can personalize your window installation until it’s perfect. From expansive bay windows to compact awnings, all of our replacement windows save energy thanks to features like low-e glass (you know what that is now!) and ENERGY STAR®-certified glass. To get a comprehensive consultation with our team of experts, contact West Shore Home today!