Low-E glass (Low Emissivity) typically improves the U-value significantly, helping reduce heat loss while allowing light to pass through. Depending on the type, it can have U-values as low as 0.5 W/m²K for double glazing and 0.3 W/m²K for triple glazing.

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How to Know:

Ask for the U-value or energy performance certificate for the specific Low-E coating and glass configuration used.