U4 - 4th Surface Technology™. Achieve triple-glazed performance in a double-glazed window.

Position yourself ahead of the energy performance curve.

U4 - 4th Surface Technology is a true game-changer for your insulating glass windows – improving your total window U-value performance by 0.04 or more without changing your manufacturing processes. Now you’ll be able to exceed the new ENERGY STAR® standards and still maintain your competitive edge. It's all part of AGC's commitment to developing innovations that keep you ahead of the curve.

How does it work?

Adding a low-e coating to surfaces #2 and #4 of an insulating glass unit allows the window to reflect energy both to the outside and inside. The coating on surface #2 will reflect solar energy to the outside when the sun is shining. During cold conditions, the coating on surface #4 will reflect energy back into the room. This reduces the amount of energy transferred across the airspace, therefore improving the overall insulating properties of the glass by an additional 15%-20% versus a conventional low-e unit.