What is Low-E?

Low-E (low emissivity) is a microscopic coating applied to one face of the glass. It reflects part of the infrared radiation: in winter, that helps keep heat indoors.

And in summer?

Depending on coating position and Low-E type, you can also limit some incoming solar heat. Options like Solarban push solar control further: less overheating, a bit less useful solar gain in winter.

In practice

Almost every high-performance window sold here has Low-E. What changes is the Low-E + argon + double/triple (or 6+4) + frame combination — not the word Low-E alone.