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A house with old, single-paned windows can be a source of drafty air, especially in the wintertime. Even worse, they can be rough on a home’s energy efficiency, making your wallet take a hard hit when it comes to winter utility costs.

Replacing old, outdated windows is one of the most effective ways to invest in long-term energy savings. While the initial investment in replacement windows may feel overwhelming, modern energy efficient windows are well worth the price, and offer significant month-to-month savings.

Choosing the right replacement windows can feel overwhelming, especially if you don’t understand all the information, numbers, and acronyms on the labels. Whether you plan to purchase your new windows online or in the store, window labels are a key source of information, making it easy to compare different models. Deciphering the label information will enable you to make an informed decision and make a wise window investment.

Understanding Window Labels

Use this information to help you analyze window label info with this handy guide.

Manufacturer’s Labels

One section of the window label contains specs from the manufacturer. It will usually include the model number of the specific window design. Other features the manufacturer’s label might include are:

The material used in frame construction. Common frame materials include aluminum, wood, vinyl, and fiberglass.

Number of panes. The manufacturer’s label should specify if the windows are single, double, or triple paned. The more panes a model has, the more protected your home is from the cold air outside.

Multi-pane windows contain gas in the spaces between the panes. The type of gas used should be listed on the label. Argon and krypton are common gases used in modern energy efficient windows.

Some models feature panes treated to protect your furniture, carpet, and drapes from harmful UV rays. Over time, UV exposure can cause fading. Low-E is a common glass treatment that helps filter harmful ultraviolet light.

The NFRC Label

Modern windows also contain a 4-5 digit NFRC rating. The National Fenestration Rating Council (NFRC) calculates this rating. This independent organization evaluates windows and skylights. The HFRC number allows you to easily compare key characteristics of different window models. These characteristics include:

Visible Transmittance. This is a measurement of how much light a specific window allows to pass through. Higher visual transmittance means more light will enter your home. This could help save on electrical costs for artificial lighting and can also help your home feel more comfortable and inviting.

Solar Heat Gain Coefficient. This number indicates how effectively the window blocks outside heat. The lower the Solar Heat Gain Coefficient, the more the new windows will save you on your summer cooling bills.

U Factor. The U Factor indicates how effectively the window traps heat inside your home. Lower U Factors are desirable, indicating greater energy efficiency during cold winter months.

Air Leakage.  This number measures how tightly the windows are sealed.  A lower number means the window will let in less air from outside.

Energy Star Label

Windows that meet certain performance criteria will feature the Environmental Protection Agency’s Energy Star label. These windows meet specific levels of energy efficiency for specific regions of the United States.

Because homeowners in cold climates need different window properties than those in warmer climates, there is no one-size-fits-all window model. Energy Star criteria also differ for different climates, reflecting the specific energy needs of homeowners in the area. The EPA divides the country into four distinct regions, Northern, North-Central, South-Central and Southern, and windows are rated according to each region based on NFRC measurements for U Factor and Solar Heat Gain Coefficient.

Consult the Professionals

If you want more information about how you can make your home more energy efficient and lower your utility bills, contact a local professional. A local HVAC technician can evaluate your home’s energy efficiency and suggest steps to help increase efficiency.