What is Low‑E, Anyway?

Low‑E stands for low emissivity, referring to a microscopic metallic coating on glass that reflects infrared (heat) radiation. In essence, it acts like sunscreen for your windows—keeping warmth inside during winter and reflecting heat out in the summer months.

The “Number” Behind the Coating

When you see a Low‑E number (or E‑value), it’s quantifying how emissive the coating is: lower = better. For example, a window with an E‑value of 0.05 will perform better at holding heat in than one rated at 0.20.

Why the Rating Matters for Your New Home

• Energy Savings & Comfort: This coating helps reduce heat loss up to 30–50%, meaning your heating and cooling systems won’t have to work overtime—saving you money year after year Wikipedia+9Panda Windows & Doors+9EcoHome+9.

• UV Protection & Durability: Low‑E coatings can block up to 99% of UV light, protecting your furniture, floors, and fabrics from fading stanekwindows.com.

• Customized Climate Control: Depending on whether you live in a warmer or colder area, coatings can be placed on interior or exterior panes to optimize performance jeld-wen.ca.

How Low‑E Fits into Window Ratings

Low‑E glazing contributes to two critical energy ratings certified by the NFRC:

1. U‑Factor – Measures the rate of heat loss (lower = better).

2. Solar Heat Gain Coefficient (SHGC) – Measures how much solar heat enters (lower = less heat transmitted) 

The Low‑E layer helps improve both: it insulates against heat loss and reduces solar heat gain. That means greater comfort and reduced utility costs year-round.

Installation: Every Layer Counts

Low‑E works best as part of a high-performance unit:

• Multiple Panes (double or triple glazing)

• Argon/Krypton gas fills

• Thermally efficient frames like vinyl or fiberglass LinkedIn+3miwindows.com+3LS Building Products+3Wikipedia+1Wikipedia+1Panda Windows & Doors+2jeld-wen.ca+2Wikipedia+2

At Rumson Window, our high-efficiency units integrate these elements beautifully, maximizing the power of the Low‑E coating. Those Low‑E numbers on our site show you exactly how effective your windows and doors will be in managing energy—no guesswork.

Bottom Line: Low‑E = Smart, Sustainable

• Better comfort – Say goodbye to cold drafts and hot spots.

• Lower bills – Less strain on your HVAC, more savings.

• Protection – Guard your interiors from harmful UV.

• Eco‑friendly – Smaller carbon footprint, more home value.

With Low‑E rated windows and doors from Rumson Window, you're not just framing your home—you’re framing your future.

Thinking about pushing energy ratings even further? Rumson Window offers deeper insights into selecting the right Low‑E coatings and configurations to match your specific climate and design goals. Explore the rating labels on our listings—you'll know exactly what performance you’re getting.

Ready to design your dream window? Let’s build something energy-smart together.