Condensation on windows is a moisture management problem, not a glass quality problem. Understanding which type of condensation you have determines whether double glazing helps — and how much.
Three Types of Window Condensation
Type 1: Internal surface condensation Moisture from humid indoor air condenses on the cold inner face of the glass. This is the most common and most visible type. Happens on winter mornings, in kitchens and bathrooms, and overnight in bedrooms.
Type 2: Inside-the-unit condensation Moisture forms between the two panes of a double glazed unit. Means the IGU seal has failed and the desiccant is saturated. The unit needs replacement — this is a glass failure, not a humidity issue.
Type 3: External (outer face) condensation Moisture on the outside of the glass on clear, cold nights. Counterintuitively, this is a sign that your glass is performing well — the outer pane is cold because heat is not passing through from inside. Common on Low-E glass and generally not a problem.
How Double Glazing Fixes Internal Condensation
Internal surface condensation forms when the glass temperature falls below the dew point of the room air.
Single-pane glass has a U-value of ~5.8 W/m²K — the inner surface becomes very cold. On a 7°C Melbourne morning with a heated room at 20°C and typical indoor humidity, the glass surface temperature can drop to 5–8°C, below the dew point.
A standard double glazed IGU raises the inner surface temperature to 12–14°C. Low-E double glazing reaches 16–18°C. At these temperatures, condensation does not form under normal residential humidity conditions.
In most Melbourne homes, retrofit double glazing eliminates internal surface condensation completely.
The One Scenario Where It Doesn't
If your indoor relative humidity is consistently above 65–70% — common in poorly ventilated homes, older homes without exhaust fans in kitchens and bathrooms, or homes with significant moisture sources — even Low-E glass can still show some morning condensation.
The fix in these cases is ventilation improvement alongside the glass upgrade. Double glazing alone does not address a fundamentally humid building.
Getting a Specification
For Melbourne homes with condensation concerns, hard-coat Low-E as a minimum is the recommended specification. It reliably keeps the inner glass surface above dew point under normal conditions.
See: Energy Efficient Windows Melbourne and Low-E glass explained
The Instant Estimate tool prices Low-E configurations for your specific windows.
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