Have you been hearing more about single, double and triple glazing lately? If you have been designing your own home, there’s a good chance that you’ve come across this question at some point – “Should my windows be double glazed?”
When we’re talking about your home’s thermal performance, this is a very big question to ask. So, let’s take a moment to unpack what glazing is and what it means for your household.
What is glazing?
Glazing refers to the glass pane installed in a window frame. References to single or double glazing simply mean how many glass panes there are separating the indoor and outdoor spaces. Generally the higher the glazing, the better the thermal performance of the window system.
Windows are a considerable source of heat loss and gain in homes. It may help to think of windows (and sliding doors) as holes in the hull of a ship. The walls of your home, much like the hull, are great at keeping out unwanted ingress of heat. However, every square meter of glass is much like replacing portions of your ship’s hull with cardboard instead of steel. It’s not a great solution, and the higher portion of your ship’s hull replaced with cardboard, the quicker and greater your chances are of sinking. The perfect building envelope for thermal comfort is one without any openings.
However, we still need windows and doors to access rooms, let natural light in and allow for ventilation. Therefore we need to make some compromise when we look at thermal performance in tandem with the building design overall.
Single glazing involves only a single pane of glass. Large areas of floor to ceiling single glass pane are a great way to have a poor thermally performing design.
In winter, a single glazed window could lose more than 10 times as much heat as the same area of insulated wall. In summer, the same west-facing single glazed window could let in more than 50 times as much heat as the same area of insulated wall.
Having single glazing isn’t taboo and it doesn’t mean your project won’t ever pass compliance. It does mean you may have to work more than if you had opted for double glazing, and you may have to keep an open mind on other compromises instead.
Double glazing includes two panes of glass, usually separated by an air gap or an inert gas such as argon. Double glazing helps significantly to minimise unwanted thermal gains or losses but is usually an expensive option since it has not yet the cost savings usually seen at levels with mass production. Canstar’s quick search suggests a ballpark figure of $1,350 per square metre, while hiPages mentions between $800 – $1,500 per square metre specifically for timber-framed (aluminium framed would cost less).
At those rates, the bill can quickly stack up! But with improved specs compared to single glazing (we’ll get into those in another article), you’re just about guaranteed your money’s worth in the long term through greater energy savings and even peace of mind with noise reduction. And you could even keep your floor-to-ceiling panoramic views, too!
Speaking anecdotally, I was lucky to experience the difference double glazing made in an apartment rental of ours on Sydney’s lower north shore. Strata had approved the window upgrades to all units and, for the first time, we could run around our rental in shorts in the middle of July (instead of throwing on three layers to stay warm). We could finally do away with the pedestal fans and cheap heaters.
What’s right for me?
It all depends – no two homes are built the same and the needs of every household are different. This is why we work with you to figure out your options (rather than just recommending you the most expensive product and calling it a day).
Reach out to us if you want to find out more, stay tuned for future articles or otherwise have a look at our further reading to learn more about windows and glazing.
Find out how we can help you with your project.