Buyer Guidance
Understanding window energy ratings (U-Factor, SHGC, NFRC)
What the numbers on a window energy label actually mean for a Long Island home.
Quick answer
On an NFRC label, U-Factor measures how well a window keeps heat in (lower is better), and SHGC measures how much solar heat it lets in (lower keeps you cooler). For Long Island's mixed climate, look for low U-Factor and a moderate SHGC, with Energy Star certification.
The key numbers
The NFRC label standardizes ratings so you can compare windows fairly. Focus on U-Factor (insulating ability) and SHGC (solar heat gain). Visible Transmittance and Air Leakage round out the picture.
What is right for Long Island
Long Island has cold winters and warm, humid summers. A low U-Factor keeps heat in during winter, while a moderate SHGC helps control summer heat. Energy Star certification bundles sensible targets for our climate zone.
| Rating | What it measures | Better is |
|---|---|---|
| U-Factor | Heat loss / insulating ability | Lower |
| SHGC | Solar heat let in | Lower (for cooling) |
| Visible Transmittance | How much light passes | Higher for brightness |
| Air Leakage | Draftiness | Lower |
EcoView windows are NFRC-tested and Energy Star certified for Long Island's climate.
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Frequently asked
What U-Factor should I look for?
Lower is better for our winters; Energy Star sets appropriate targets for the Long Island climate zone.
Is a lower SHGC always better?
For cooling-dominated needs, yes; a moderate SHGC balances winter solar warmth with summer heat control.