The benefits of double glazed windows and why they also make sense in Australia!

We’re currently in the process of making our own double glazed windows for our tiny house! Yes, seriously! We took on that monstrous task because we’re dissatisfied with the overall window situation here in Australia.

We want the windows in our tiny house to be super energy efficient in order to reduce the amount of energy we have to spend on regulating the temperature inside the house. In order to achieve this, our windows have to be absolutely airtight and double glazed.  

The benefits of double glazed windows

Double or triple glazed windows are standard practice in Europe and North America. They offer a lot of great benefits. Even the ancient Romans knew about that because they’ve used insulated glazing to keep their public baths warm. That’s quite impressive!

One of the biggest advantages of double glazed windows is that they have very good insulating and thermal qualities. This means that you will spend less money on heating or cooling your home. According to Efficient Windows, installing double glazed windows can save you up to 43% on your power bills! Another great advantage is that it blocks out traffic noises because of its’ thickness. Double glazing also reduces condensation which in addition also prevents mould formation. Lastly, because double glazed windows are made from laminated or thickened glass, they are a lot harder to break which increases the security of your home.  

Mission impossible

These are all great benefits. So why wouldn’t you want double glazing in your home? We started to look around for second hand double glazed windows. We wanted to save money and also be more resourceful rather than buying new. But there is basically nothing out there. So we considered getting them custom made. We got quotes from window makers. But either the e-value of the glass they use isn’t energy efficient enough or the windows are simply too expensive.

What a difficult mission! We learned the hard way that double glazing isn’t very common in Australia.

There seems to be a common belief that double glazing is only useful in cold countries and therefore pointless in Australia. Another reason is money. It is true that double glazed windows are more expensive than regular windows. Double glazed windows will save you money in the long run though. According to Ecohomesolutions builders and house buyers alike seem to “believe that keeping the capital cost down is the best way to improve housing affordability”. (…I’m secretly rolling my eyes here…)

While I get that money is tight and we’re all hesitant when it comes to spending more money on something that we can get cheaper, we also know that buying quality always pays off. More importantly, we all have to do our part these days in stopping the climate change. This can only be achieved by reducing our greenhouse gas emissions and by living more resourceful. So where am I going with this lecture?

The disadvantage of single glazed windows

While single glazed windows might be cheaper initially, they will not save you any money later on. Single glazed windows don’t have any thermal qualities. This means that cold air can come through in winter which makes your house even colder, while in summer hot air is coming in which makes your house even hotter. Therefore you have to use heaters or coolers in order to regulate your home and this will ultimately lead to burning more fossil fuels and also show on your utility bills.

According to  Sustainable Construction Services, the majority of energy in a household is used for heating and cooling and amounts to 36%. They also point out that “heating and cooling of living and work space constitutes almost half of a building’s energy consumption”.

Therefore it makes sense to build a new home with energy efficiency in mind. In addition to that, it’s also important to be aware of your behaviour when it comes to energy consumption because some habits might cost you a lot of money. For more useful tips on how to save energy in your household, have a look at YourHome’s website.

What is double glazing?

Obviously, we’re a bit obsessed with installing super energy efficient windows into our tiny house. So what’s the big deal? We’re living in Australia where it’s always hot and windows don’t have to serve a higher purpose, right? Wrong!

The beauty of double glazed and airtight windows is that they work both ways. This means that they offer great benefits for cold and warm climates. But let’s start from the beginning. What actually is double glazing?

To put it very simple double glazing means that the window unit contains two panes of glass instead of just one. This window unit has to be absolutely airtight to work its’ magic. Professionals also call this unit IGU which stands for insulated glass unit. Some IGUs are even triple glazed for even better energy efficiency qualities, however, triple glazing only makes sense in very cold climates like Europe or North America.

How does double glazing work?

Now we know what double glazed windows are but how exactly are they saving energy in a house? In order to answer this question, I have to explain how double glazing works.

The two panes of glass inside the IGU are separated by a gap. This gap has to be fully sealed. It can vary from 6 mm to 20 mm but in order to achieve the best results its’ ideal width is 12 mm.

The gap is very important because it adds a layer of insulation to the window. This layer, therefore, acts as a thermal resistance between the inside and outside of the house. In other words, it reduces the amount of warm air escaping the house in winter and prevents hot air from entering the house in summer.

The thermal performance of the gap is even better if space is filled with gas. Argon is most commonly used for this purpose because it has low conductivity properties which improve insulation.

I think it’s safe to call this gap the MVP of a double glazed window!

Double glazed windows make sense in Australia

So now we know that double glazed windows totally make sense in hot climates like Australia too!

Besides, the research for this article has shown that double glazing is not a stranger to Australia. All the websites I quoted from are Australian based and there are companies building and (hopefully) selling double glazed windows. A lot of them seem to be in Victoria by the way. Australia even has its’ own window association called AWA which is promoting double glazed windows in their in-house Windows Magazine.  

Unfortunately, though double glazing is still far away from being standard here. Companies are aware of this fact too. Eco Solutions, for example, is pointing out that Australia is still “far behind Europe and North America in the adoption of double glazing”.

Our window project

This leads us back to our own window project. What a task! While we understand the concept of a double glazed window, it is really hard to build one yourself. It’s quite technical and a lot of planning is involved beforehand. Using the right tools helps too. We find that when it comes to the big guns, a table saw and a router does the trick.

Also, we’re using acrylic for our windows. There are two reasons for this. First, we have to watch the weight we put on our trailer and double glazed windows are significantly heavier than normal windows. Second, we will potentially move the tiny house and are afraid that the glass might break. But acrylic has even better qualities to offer than glass because it’s very lightweight, very energy efficient and very durable.

We also learned the hard way that it’s really difficult to self-build an airtight IGU. Condensation was building up between the two panes of acrylic when we put the window in the sun.

Therefore we decided to go with only one thick pane of acrylic instead of two thinner ones. So far this is just a theory, we haven’t got the chance to test it yet because we’re still building frames but I will post regular updates.

Please leave a comment if you can share some advice on building airtight windows! Thank you 🙂