Double glazing and how it works

For the ultimate way to keep your home warm over winter, look no further than double glazed windows. This is a pretty simple technology – but it can work wonders.

Story by: David Renwick Photography by: Jamie Cobeldick

Heat pumps, fireplaces and other heating technologies are key to a warm winter home, but there’s another method to consider: Double glazing.

By pairing this useful technology with efficient types of heating, you can create a warm, dry home that keeps winter at bay.

How does it work?

There’s really no technical wizardry involved with double glazing. It works by trapping air between two panes of glass – that’s it. The trapped air forms a layer of insulation, preventing heat loss (and gain).

It’s really the same as any other form of insulation, like fibreglass batts or polystyrene.

By installing double glazed windows, you also gain a few other useful benefits. For one, you’ll find condensation far less of an issue. Condensation occurs when the cold air outside your home cools the warm air inside, but thanks to the insulating barrier, the cold air cannot interact with the warm air, meaning no condensation.

Double glazed windows also permit radiant heat to enter the home, meaning you won’t miss out on the warmth of the sun in winter.

What about Low E glass and argon gas?

By using Low Emissivity (Low E) Glass with argon gas sealed in between the two panes of glass, you can increase the thermal performance of your windows even more. Basically, this means you'll have a more consistent temperature in your home in both winter and summer.


A wall of new double glazed windows – ceiling, interior design, living room, loft, real estate, room, white
A wall of new double glazed windows – and this skylight – were installed as part of a major renovation of this home

How can I get it?

If you’re already got a home, you’ll want to consider retrofit double glazing. This means replacing the existing windows in your home with new, double glazed alternatives. 

This isn't as major as it sounds.

These days, you can keep all the existing framing – if it's in good condition – and just replace the glass itself. 

The old single glazed pains are popped out, and the new double glazed panels fitted in. A new trim, matched to the existing one is then installed to hold the new panes in place.

It’s a simple and relatively quick process, and you won’t notice any difference – inside or out. Well, aside from the insulation of course!

For those building new, it’s even simpler. 

In the planning stages of your project, just tell your builder or building company that you’d like to use double glazed windows.

Note that for most new builds in New Zealand, there’s a good chance you’ll be required to install double glazing.

Effective heating for your entire home

As we noted at the start of this guide, double glazing is just one part of an effective home heating strategy. We’ve also got this guide here, which covers some of the things to consider when it comes to heating.

If you’d like to learn more about one of the double glazing products available in New Zealand, Metro Glass have a helpful webpage. They’ve also got Low E double glazing for existing homes.

Jul 11, 2018
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