Double Glazing Explained

Can Double Glazing 100% Eliminate Condensation?

It’s a common experience for home owners during our installation process: they notice a massive change in the reduction in condensation on their windows.

A good example of this is a project completed in the Reporoa Valley in the middle of winter. The home had a real issue with condensation on their aluminium framed windows and doors. They chose to have The Double Glazing Company install high performance double glazing into their existing windows and doors.

Reporoa gets really cold in winter and has the Waikato river passing through this valley, so tends to be a trap for humid conditions during this season.

During the install, the homeowners noticed a profound difference between the old single glazing and the new high performance double glazing. The photo at the top of this post was taken during the project.

The photo shows a huge amount of condensation on the single glass panes (right hand side). In stark contrast, the double glazing is dry (left hand side).

How does double glazing stop condensation?
Condensation forms on a surface when the temperature of that surface is equal or lower than the “dew point” of the air. (The dew point is the temperature at which the moisture in the air condenses).

Double glazing is also known as “insulating glass”. That’s because it provides an insulating layer from the outside to inside. The Double Glazing Companys Supertherm double glazing does an even better job of this, meaning that the temperature of the glass on the inside is much less likely to reach the dew point. That’s how double glazed windows can help stop unwanted condensation and the associated water damage, mould and mildew and the health impacts.

But 100% of the time? Really?
Let’s answer this with an extreme scenario. In late 2015, we built a new home in Taupo. It’s built on passive solar house concepts that includes triple glazed windows made here in New Zealand (something something something) and a European balanced pressure ventilation system. The point is that this is a highly insulated house with controlled humidity. One recent morning, I noticed that one of the high windows in the master bedroom had a “huff” of condensation on it. It was barely noticeable, but given the context of the home, a little troubling! That is, until I considered the scenario. Next to the bedroom is an ensuite and someone (no names mentioned!) had just had a long, hot shower. Even though the ventilation system would have ramped up due to the increase in humidity, this had not been enough to stop the humidity rising in the bathroom and into the bedroom (the ensuite door had been left open). While the bedroom itself was not noticeably humid and the glass was not all that cool, the conditions had still