Interior of a bay window, showing white single-hung Willmar vinyl windows.

White single-hung, dualpane windows from JELD-WEN’s WIllmar Collection.

An inert gas such as argon is denser than air. When it is injected into the dead airspace between two window panes, argon gas improves the insulation by reducing convection heat loss within the sealed unit.

FAQ Friday is a weekly feature where we answer Frequently Asked Questions about our products, service or industry. To see other FAQs we’ve answered, visit our FAQ page. If you have a question you don’t see an answer for, just ask in a comment or contact us.