Window Defogging Services: Do They Work?

Defogging services promise to clear foggy windows at a fraction of replacement cost. According to industry research, the reality is more nuanced.

What Defogging Does

According to GANA (Glass Association of North America), typical defogging involves:

1. Drilling small holes into the glass unit
2. Cleaning or drying the interior space
3. Injecting anti-fog solution
4. Installing one-way vents to prevent future moisture buildup

The process removes the visible fog and prevents recurrence.

What Defogging Doesn't Do

According to FGIA, defogging has critical limitations:

Doesn't restore insulating gas: The argon or krypton that made the window efficient is gone. It's not replaced during defogging.

Doesn't restore efficiency: According to FGIA, a defogged window performs like clear double-pane glass (U-factor ~0.50) rather than Low-E filled glass (U-factor ~0.27).

Doesn't address permanent haze: Mineral deposits etched into glass surfaces won't be removed.

Doesn't prevent frame issues: If frames are deteriorating, defogging the glass doesn't help.

The Math

| Option | Cost (per window) | Energy Performance |
|--------|-------------------|-------------------|
| Defogging | $75-150 | Reduced (like clear glass) |
| Glass replacement | $200-400 | Like-new if re-gassed |
| Full window replacement | $400-800 | Better than original (newer tech) |

When Defogging Makes Sense

According to GANA, defogging may be appropriate when:

• Fog is purely aesthetic concern
• Windows are otherwise in good condition
• Budget doesn't allow replacement
• Energy efficiency isn't priority
• You're planning to sell the home soon

When Defogging Doesn't Make Sense

Consider replacement instead when:

• Windows are 20+ years old
• Frames are deteriorating
• Energy efficiency matters
• Multiple windows have failed
• You want long-term solution

The Bottom Line

Defogging is a cosmetic fix, not a performance restoration. If the fog bothers you and the windows are otherwise fine, it can be cost-effective. But don't expect it to restore energy efficiency.

*For complete guidance, see: [Foggy Windows: Repair vs. Replace](/guides/foggy-windows-repair-vs-replace)*