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What Window Labels Say About HVAC Efficiency

When it comes to staying warm in the winter and cool in the summer, we tend to think predominantly about our HVAC system – the furnace and AC, vents, ductwork and all other related components. This is natural, as these elements are the primary pieces of equipment that dictate your home’s heating and cooling.

At Roberts Mechanical, however, we’re here to tell you about another home component that’s vital for winter heating and summer cooling: Your windows. Windows are among the primary holders of air in your home, stopping it from escaping to the outdoors and forcing your furnace or AC to work harder to pump more back in – costing you money in the process.

With this in mind, let’s look at some of the important window labels you need to know about. Whether you’re shopping for new windows or just looking to assess your current ones, here are the important facts to know about what these say about window efficiency.

Manufacturer Label

There will be multiple panels on a given window label, each telling you different things. One such panel will be from the manufacturer of the window, and it will state the manufacturer name plus a model number for that design. Just below this will be specific product features, potentially including:

  • Frame materials: Generally wood, aluminum, vinyl, steel, or fiberglass composite
  • Number of panes: Single-pane, double-pan, triple-pane
  • For multi-pane windows, the type of gas that fills the gap (generally krypton or argon) will also be listed
  • Glazing style
  • Low-E: A specific glass treatment that limits the impact UV rays can have on your carpets or furniture – without this, these materials may fade over time due to UV rays

NFRC Label

Once you’ve moved past the basic window information, you’ll also notice four or five numbers in bold on the label. This is the NFRC label, with data calculated by the National Fenestration Rating Council – this group tests windows, doors and other openings and certifies them based on their quality. Important elements of the NFRC evaluation include:

  • U-Factor: How well windows keep heat in the home – lower numbers mean better energy efficiency, while higher numbers are worse.
  • Visible transmittance: How much light a window lets in – higher numbers mean more light.
  • Solar heat gain coefficient: How effectively windows block heat from outside that isn’t desired inside. The lower the number, the more efficient.
  • Air leakage: How much air of any kind the window lets in. Again, lower numbers are better here.
  • Condensation rating: Only found on some NFRC label, this rating tells how well a window resists condensation, with a higher number equaling better resistance.

Energy Star Logo

You may also see the Environmental Protection Agency’s Energy Star logo on your window, which means it’s highly efficient for your area. There’s no single set of criteria here – certain windows are designed for specific climates, so they’re divided into smaller regions and then assessed based on NFRC measurements for U-Factor and solar gain coefficient.

For more on what your window labels tell you about their air efficiency, or to learn about any of our HVAC services, speak to the pros at Roberts Mechanical today.