Why do all Aluminium Windows need to be Thermally Broken?
Having grown up in Australia, I have a lived understanding of the basic building performance and function, along with what our homes are meant to provide for us, i.e. shelter, comfort, protection from the exterior weather conditions, hot and cold etc.
"Unfortunately, Australian homes are more closely related to glorified tents than to high-performance structures!"
Until recently (early 2022), my family & I, have lived in the leafy eastern suburbs of Melbourne (Climate Zone 6) for the past 30 years or so. Before moving to Melbourne in 1988, I grew up in Brisbane, the warmer, more humid temperate zone (Climate Zone 2) that Queensland offers compared to Melbourne, Victoria.
When we think of Brisbane, we believe that it doesn't get cold like Melbourne and hence single glazing is the standard default glazing option in homes. Experience has shown me that Brisbane can get very cold in winter; see the tables below:
From the climate data displayed above, I would say that Climate Change is very obvious.
"I believe that Brisbane homes need to be Double Glazed as much as they do in Melbourne, though for different reasons. Ultimately all homes in Australia should be Double Glazed for the same reasons. Hot will go to where it's not."
Vince Wardill
I have only ever lived in houses that are single glazed until now. I know the cold that these homes can allow to enter into the building, via the cold glass and aluminium frames in winter and have experienced 11 degrees Celsius inside our old home in the eastern suburbs of Melbourne overnight.
Inversely, the heat of summer on a 40 degrees Celsius day in Melbourne or Brisbane seems unbearable without air-conditioning. Again, all that heat typically enters the building (Home) via poor single glazing and aluminium frames.
Knowing that Double Glazing gives better thermal performance (as I work in the industry), I've only just started to have the learned experience of what a difference this product makes to the thermal comfort of our homes (having moved into a newish apartment in the Docklands in Melbourne which was only completed in 2015).
What struck me recently, was the heat that even Double-Glazed Aluminium Windows (non-thermally broken) can admit into the building envelope.
Picture this scenario!
Lying in bed on ANZAC Day 2022 watching the Dawn Service, the Morning News and then finally the start of the ANZAC Day Parade down Swanston Street toward the Melbourne War Memorial.
It's about 10 AM AEST in the morning, and my bedroom glazing is facing North-East. The ambient air temperature outside is 18 degrees Celsius.
I see thermal heat lobes fluttering across the bedsheets of my bed. This fascinates me, as this isn't something that the human eye can normally see!
I'm moved to touch the aluminium frame and double glazing of my windows (again this isn't something that most people do) as typically we look through glazing and don't touch it. We typically don't realise how hot aluminium framing and glass actually gets!
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What I discovered was that the aluminium frame was quite hot. Hot to the point that I understood why my room was getting hot (and it wasn't because of me)! This raised my curiosity levels to the point where I grab my Flir C3 Thermal Camera and start taking images. Find what I discovered below.
What I discovered was that with an outdoor ambient air temperature of 18 degrees Celsius to 19 degrees Celsius, and an indoor air temperature of 20 degrees Celsius, we were really getting more than 60 degrees Celsius on parts of the non-thermally broken Aluminium Frame, and this was having an adverse effect on the double glazing and the temperature inside the building. This heat gain primarily comes from the SHGC (Solar Heat Gain Coefficient) from the glass and aluminium frame system. This is because Aluminium is highly conductive!
This is where Thermally Broken Aluminium Windows would really help.
Based on the 2 window systems shown here, we conducted a thermal simulation to show the effects of using a thermal break. The results showed that for the thermally broken system, the U-frame value has been reduced from 6.56W/m2K to 3.58W/m2K, reflecting a significant 45% reduction!
We can also observe that the temperature of the interior aluminium frame is much lower, as demarcated by the blue region, suggesting that the thermal break has effectively reduced heat gain through the aluminium framing. This will also mean that your double glazing can perform better.
Above is an example of a double-glazed window struggling to perform due to the cold non-thermally broken aluminium frame that the double glazing sits in. The window on the right is showing the cold of the frame leeching into the double glazing.
The window on the left is Thermally Broken Aluminium and hence is performing very well. The interesting thing to note here is that the Double-Glazed unit (IGU - Insulated Glazed Unit) in each window has the same specifications! They are obviously performing very differently due to the difference between the Thermally Broken Aluminium window frame compared to the Non-Thermally Broken frame.
Windows are supposed to keep the occupants of the building separate from the outdoor climate but using aluminium framing creates a thermal bridge in the building envelope. Heat easily travels in and out of a building via the aluminium window frame. This means that there is a constant battle to keep buildings cool in summer and warm in winter. The occupants of the buildings are less comfortable and face higher energy bills.
Aluminium frames are highly versatile, low maintenance, long-lasting and low cost. It is no wonder it's the most sought-after window framing material in the New Zealand and Australian markets. However, there is one massive drawback to using this type of framing material... and it's the same reason aluminium is such a sought-after material for the base of cooking pots and pans. I repeat: Aluminium is highly conductive!
We have the technology in Australia to make this happen for all homes. We just need the education, regulation and appetite for better-built outcomes for all Australians and our housing stock to bring this to reality.
Double Glazing is basically insulation being added to the last remaining part of the building envelope that we haven't insulated previously in Australia. Double Glazing is suitable for both Hot and Cold climates.
Should you require any further information on this subject, please do not hesitate to contact us at Technoform as,
“We want all Australians and New Zealanders to have the opportunity to live & work in buildings that are healthy, comfortable & cost substantially less to run!"
Contact Details for Technoform ANZ (Australia/New Zealand) :
Vincent Wardill - National Business Development Manager, Mobile: +61 455 11 77 95, Email: vincent.wardill@technoform.com, Website: www.technoform.com
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2yVincent, thanks for sharing!
National Specification Manager
2yGood one Vince. It is definitely a time to move onto high performing windows so that we can actually enjoy staying inside regardless of the weather and without having to be heavily dependent on power-hungry services.
Sustainability Consultant at SUHO
2yWell written Vincent Wardill
Experienced Window Industry Executive at Technoform
2yExcellent post Vincent, everyone in the Australian Wndow industry should read this. Clinton Skeoch it really is time to get behind much better performing windows to support the health and well being of Australians. There is no doubt Australia is going to have to deal with Hotter, Wetter, Drier, Colder in the extremes and much better performing windows do have a massive impact on the livability of homes.