Getting ready to update your Long Island home with high-performance, energy-efficient replacement windows? If you haven’t purchased home windows recently, you may need some additional information about low-E glass and the role it plays in running an energy efficient home. Renewal by Andersen of Long Island customers have several low-E glass options from which to choose to ensure each window design is appropriate for the room where the window will reside.

Here’s what you need to know about low-E glazing and replacement windows.

What is Low-E Glazing?

The term low-E is a shortened version of low-emissivity. Emissivity refers to factory applied glass coatings that reduce the amount of heat that passes through the glass portion of your new replacement windows. Low-E means less heat passes through the glass panel than through a similar window manufactured with standard float glass.

How Does Low-E Glass Reduce Energy Costs?

According to the National Fenestration Rating Council (NFRC), the average American household spends between $675 and $1,125 each year on heating and air conditioning costs. Having high-performance replacement windows and patio doors installed can help you save money while maintaining a comfortable indoor environment.

Low-E glass helps homeowners control cost by managing heat gain through the window. When sunlight directly hits a window with low-E technology, less heat transfers to interior spaces. During hot summers, this is a wonderful tool to lower air conditioning expenses.

While reflecting heat away from your home during the summer is great, it is important to realize that to some extent low-E glass always reduces the amount of heat that passes through a window. So, during winter, when you might want to take advantage of heat gain to reduce heating bills, you’ll need a window with a slightly different low-E technology to maximize your saving potential.

Is There a Magic Formula for Designing High Performance Replacement Windows?

Creating a best-fit window for every room is a bit of a balancing act. First, you must decide whether your winter heating load will be greater than your summer cooling load, or vice versa. Then, you’ll want to determine which windows receive direct sunlight, and how many hours per day.

While there isn’t one glass type that will work exceptionally well in every setting, getting comfortable with the performance label information will help you make an informed decision about which glass type is best for each room in your home. It is important to pay close attention to both the Solar Heat Gain Coefficient (SHGC) and the Visible Light Transmission (VT) numbers as you explore brands and styles.

The SHGC gives you a better idea of how much solar gain is going to contribute to overheating during the summer months, and higher air conditioning bills, and how much extra heat will give you a break on your winter heating costs.

You can learn more about performance labels by visiting the NFRC website or

What Else You Should Know About Low-E Glass Performance

We’ve discussed low-E glass, and how modern technology helps control comfort and your home operating budget. Your window frame material also impacts your replacement window performance, we’ll discuss that topic in another blog post soon. In the meantime, if you need more information about low-E glass options, fill in the short form on this page or dial 1-877-313-9052 to speak to a Renewal by Andersen of Long Island window design consultant.


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  • The Difference Between Replacement and New Construction Windows!
  • The Different Kinds of Frame Materials and What That Means to Your Windows’ Performance and Longevity!
  • How the Right Glass Can Save You Money on Your Heating & Cooling Bills!
  • The Critical Role Proper Installation Plays in the Performance, Durability and Warranty of Your New Replacement Windows!
  • What Features and Options are Important to You and What Role They Play in Your Ultimate Satisfaction Today, and for as Long As You Live in Your Home!
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