When you shop for new windows, you’ll notice a lot of technical terms on the labels — things like U-Factor, SHGC, and the Energy Star logo. These ratings aren’t just random numbers; they tell you exactly how your windows will perform in terms of comfort, energy efficiency, and long-term savings.
In this post, we’ll break down what each rating means so you can make the best choice for your home.
1. What Is the U-Factor?
The U-Factor measures how well a window prevents heat from escaping your home.
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The lower the U-Factor, the better the insulation.
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For example, a window with a U-Factor of 0.25 is more efficient than one with 0.35.
Why it matters:
In colder climates like Ohio, a low U-Factor helps keep your home warmer in the winter and reduces heating costs.
Pro tip:
Look for windows with a U-Factor of 0.30 or lower if you want top-tier energy performance.
2. What Is the SHGC (Solar Heat Gain Coefficient)?
The SHGC measures how much solar heat from sunlight passes through the glass.
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The lower the SHGC, the less heat enters your home.
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For sunny or warmer climates, a lower SHGC helps keep your home cooler and your air conditioner from working overtime.
Why it matters:
If your home gets a lot of direct sunlight, especially on the south and west sides, choosing a window with a lower SHGC can greatly improve comfort.
However, in colder regions, a slightly higher SHGC can actually help capture heat from the sun during winter months.
3. What Does the Energy Star Label Mean?
The Energy Star logo is a quick way to identify windows that meet strict efficiency standards set by the U.S. Environmental Protection Agency (EPA).
Energy Star–certified windows are tested and verified to perform well in specific climate zones. These windows typically have:
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A low U-Factor (for insulation)
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A low SHGC (for heat control)
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High-quality construction with double or triple glazing and low-E coatings
Why it matters:
Energy Star windows can cut your energy bills by up to 12% and make your home more comfortable year-round.
4. How These Ratings Work Together
When choosing windows, you don’t want to look at just one number — it’s about balance.
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In cold climates, prioritize a low U-Factor for insulation and a moderate SHGC to capture sunlight warmth.
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In hot climates, choose windows with both a low U-Factor and low SHGC to block heat gain.
The key is to choose the right combination for your home’s location and exposure to sunlight.
5. Why It Pays to Understand Window Ratings
Replacing your windows is a big investment, and understanding these ratings helps you get the most value for your money.
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You’ll enjoy lower energy bills
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Your home will be more comfortable in every season
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You’ll add resale value and energy efficiency appeal for future buyers
Final Thoughts
Window ratings might seem confusing at first, but they’re the key to making a smart, long-term decision for your home.
When you understand U-Factor, SHGC, and Energy Star, you can compare products confidently and choose windows that fit your climate, budget, and energy goals.
If you’re ready to explore energy-efficient window options, contact Kelsey Contracting at toll free 833-Kelsey-C (833-535-7392).. We’ll help you find the perfect style and performance level for your home.