What Causes Double-Pane Window Discoloration?

Discoloration is a phenomenon unique to double-pane windows. While it doesn’t happen as often, knowing what causes it can help you make informed decisions when getting new windows. In today’s post, local replacement window contractor Renewal by Andersen® of British Columbia discusses what causes window discoloration, and the best way to fix it.

How Double-Pane Glass Works

You’re probably wondering why discoloration is unique to double-pane glass. Let us first explain how it works.

Buildings, including homes, have an insulated enclosure. The roof and exterior walls are insulated using standard materials like fiberglass batts or rolls, expanding foam or cellulose made from recycled paper pulp. These materials are opaque, making them unsuitable for use on glass. This is the reason why traditional windows, made with single-pane glass, are typically areas where the building loses heat during the winter season (resulting in drafty windows) and gains heat during the summer season. In some homes, storm windows and insulating curtains have helped address the heat loss and heat gain, but not in full.

Double-pane glass, also known as insulated glass enclosures, solves the insulation problem by separating the interior and exterior surfaces of the glass. A vacuum is created by removing the air between the gaps during manufacture, which reduces the number of molecules that could have otherwise transferred heat. It has proven to be so effective that Renewal by Andersen® replacement windows come with double-pane glass as a standard component.

What Causes Window Discoloration?

Keeping the vacuum gap sealed between the glass panes is key to maintaining its insulating capabilities. However — like any other type of window glass — double-pane glass is not immune to damage. If the seal is breached by impact damage, improper use or manufacturing error, moisture can infiltrate the gap. If this happens, contaminants can make their way in, resulting in a noticeable change in color.

Since moisture is the vehicle that drives the contaminants into the double-pane glass, discoloration can be mitigated by maintaining relative indoor humidity levels between 30% to 50%.

This, however, does not fix the problem. Since the gap is no longer a vacuum, its energy performance will be diminished. Discoloration will still occur. Since it’s not reversible, the only long-term solution is to replace the affected windows. In addition to choosing durable replacement windows, make sure that the factory warranty coverage includes the double-pane glass.

When you need a replacement window company that offers all these and more, choose Renewal by Andersen® of British Columbia. Give us call at (604) 200-1025, or fill out our contact form to schedule a free consultation. We serve communities in Vancouver and Delta, BC.