Windows are a very important aspect of a home and careful consideration should be taken before accepting whatever a builder provides as standard. Typically builders wont tell you about the options that are available and simply provide the minimum required to comply with local regulations. They contribute to aesthetics, airflow, soundproofing, heating, cooling and privacy.
Your first decision is to decide on the material such as timber, aluminium or uPVC.
Timber frames are normally made from cedar which requires a lot of maintenance with sanding, re-staining, re-coating, and suffer from blackening/greying of timber. Timber can also be very expensive. If you have dogs, its very difficult to fix scratches on the doors. They can be stained in different colours and they also offer a wide profile.
Aluminium & Thermally Broken Aluminium
Aluminium is common and has little maintenance compared to timber however comes with drawbacks. If they aren’t thermally broken, more of that later, they perform poorly from a thermal perspective and will contribute significantly to the cooling and heating of a home.
Thermally broken aluminium is thermally efficient. A non-conductive piece like uPVC is placed in the middle of the frame to prevent heat and cold from transferring through. Visually it looks the same as standard aluminium.
uPVC offers many of the benefits of timber frames and aluminium but with fewer drawbacks than both. They are the most thermally efficient material and offer wide profiles like commercial windows.
Composite Windows (Timber + Aluminium)
You can also get composite windows where the inside is timber and the outside is aluminium which significantly reduces its maintenance.
|Aluminium||Thermally Broken Aluminium||Timber||uPVC|
Aesthetics (Commercial Windows) + Sizing
With smaller custom luxury builders, they will generally use commercial windows which are just thicker frames and the glass is the same as residential. With commercial and semi-commercial windows they can also provide higher (>2.4m) and wider doors and windows and allow for double glazing. All other builders will provide residential windows which are small frames and they generally can’t accommodate double glazing.
Residential windows also come in standard sizes. If you want ones that are outside of these they become custom so even a few mm less can cost you more. The difference isn’t much though per window however, they can add up.
When increasing your ceiling heights consider increasing your door and window heights as they can look out of place otherwise eg. consider 2.34/2.4m window heights with 2.7m ceilings. Also consider the head heights for the windows and make sure they are aligned with each other. For ceilings above 3m consider having standard window heights and having a highlight window above them.
Doors and windows above 2.34m might not be possible with standard residential frames so you may be forced to upgrade to commercial frames. There is also a hard limit on the height of the commercial doors so go onto the manufacturer’s website to confirm these heights.
|Stegbar||Commercial||Capral 900 (TBC)|
Types of Windows
Consider the use of the windows because some types of windows provide a sealed system like an awning window where heat and sound cant pass easily whereas a sliding window will have a small gap in the middle of the window as it cant form a tight seal. Also when it’s raining some types of windows will allow rain to come in more easily than others eg. awning vs sliding.
|Type||Airflow||Sound Isolation & Thermal loss (gaps)||Open during Rain||Pricing||Notes|
|Sliding||Great||Below avg||N||$$||These normally cost less than awning windows but thats not always the case.|
|Casement||Good||Great||Y||$$$$||You might not be able to use flyscreens on these unless you go with full commercial windows.|
|Double hung||Great||Below avg||N||$$$$$|
|Louvre||Great||Terrible||N||??||These arent good for thermal or sound protection|
|Tilt & Turn||Great||Great||Y||$$||This is a hybrid of a casement and an awning window so you get the benefits of both. It opens inwards. Its more common for uPVC frames.|
Skylights will cost around $2300 to $2700 for a fixed skylight. Theres a few different standard sizes from Velux that are worth looking into as the cost different isnt much between them.
Double glazing is where a window is constructed with 2 panes of windows that are separated by a pocket of air and that pocket of air will usually be injected with a type of gas. The thickness and type of window panels can be adjusted too.
Double glazing will help ensure there’s less thermal loss through your windows as well as provide some soundproofing to that room where its required. This will also help with BASIX/NatHERS assessments. Double glazing can be 20-40% more but when you consider the difference between $500 and $700 for a window, its not too much. This pricing also assumes the single glazing is on the commercial type of window, otherwise, the cost difference will be more.
For larger windows/doors consider the total weight of it as it might require onsite glazing (unsure how this work for double glazing) or cranes to be used as it can be too heavy for people to carry themselves.
Glazing for sound/acoustics/noise reduction
Double glazing has mixed messaging from the suppliers on its effectiveness. To be effective for sound proofing you would require a gap of over 100mm to be as effective. Wideline for instance use a product called Viridian’s VLam Hush™ which is a laminated glass product suitable for acoustic treatments. Density plays a crucial part.
Glazing for thermal efficiency
Low-e or Comfort (Viridian) are often used as alternatives to double glazing as you don’t need to upgrade the frame to commercial ranges and can save you on onsite glazing costs too.
Other window costs
Onsite glazing – If a single window is more than 80kg (there can be leniency in this) it may require onsite glazing which would cost at least $500 per window. The window may also require craning which would add another significant cost.
Thermal Efficiency & How to Compare Windows for this
WERS give you the ability to search for the performance of the windows and frames. To keep things like for like they use the same size window to compare. The important codes to know about are
- U-values – measure how well the window will retain heat in the winter and reject heat during summer. The lower the U value, the greater a window’s resistance to heat flow, and therefore the better its insulating value. This is a similar concept to the R rating for insulation however a higher rating is the target in this instance. A well performing UVal is around 2 which mostly uPVC, thermally broken aluminium and timber frames can achieve.
- SHGC (Solar Heat Gain Coefficient) – measures how well a window product blocks heat caused by sunlight. A product’s SHGC value is expressed as a decimal number between 0 and 1; the lower a window’s SHGC value, the less solar heat it transmits.
For sound and air infiltration you ideally want a window that can have a full seal when closed like an awning, casement or tilt and turn window. Sliding windows arent able to do this as well but they have improved over the years. To measure this you should compare
- AI values (Air Infiltration) – The lower the better and under 0.3 is good but this needs further investigation on the ideal values. A fixed window is 0. Wideline has an Ascend awning window of 0.22 and a Paragon sliding window which is 0.23, so not much difference between them.
Window Material Impact on Thermal Efficiency
For thermal efficiency thermally broken windows are a major factor to consider as these enable things like double glazing and low-e treatments to be much more effective. uPVC, timber and thermally broken aluminium are options here which will generally cost more than standard aluminium windows but its not always the case.
On a standard aluminium window its rare to find a UVal lower than 3 with double glazing and low-e whereas with thermally broken frames 1.5 is easily possible. A lot of people spend money changing from a single glazed window which has a rating of 6 to double glazing which just gets to 3.6 which is good but not great.
From Wideline these are the specs for comparison to see the impact of the various glazing and frame options (Paragon is the top range and Ascend a mid range):
|Awning||ASCEND Awning Window ‐ Double Glazed||4mm Clear / 6mm Argon Gap / 4mm Clear||3.8||0.52||0.53||0.22|
|Awning||ASCEND Awning Window ‐ Double Glazed||4mm Clear / 12mm Argon Gap / 4mm Clear||3.6||0.52||0.53||0.22|
|Awning||ASCEND Awning Window ‐ Single Glazed||6.38mm Clear Laminate||5.8||0.54||0.57||0.22|
|Awning||Paragon Awning Window ‐ Single Glazed||6.38mm ComfortPlus Neutral||6||0.33||0.31||0.3|
|Bi-Fold Door||Paragon Bi‐Fold Door ‐ Double Glazed||4mm Clear / 6mm Air Gap / 4mm Clear||4.4||0.52||0.54||0.38|
|Bi-Fold Door||Paragon Bi‐Fold Door ‐ Single Glazed||6.38mm ComfortPlus Neutral||4.5||0.37||0.4||0.38|
|Double Hung||Paragon Double Hung Window ‐ Double Glazed||4mm Clear / 6mm Argon Gap / 4mm Clear||4.6||0.52||0.53||1.02|
|Double Hung||Paragon Double Hung Window ‐ Single Glazed||6.38mm ComfortPlus Neutral||5||0.37||0.39||1.02|
|Fixed Window||Paragon Fixed Window ‐ Double Glazed||4mm Clear / 6mm Air Gap / 4mm Clear||4.1||0.63||0.66||0|
|Fixed Window||Paragon Fixed Window ‐ Single Glazed||6.38mm ComfortPlus Neutral||4.3||0.46||0.51||0|
|Fixed Window||Paragon Fixed Window ‐ Single Glazed||6.38mm Clear Laminate||6||0.72||0.78||0|
|Louvre||Ascend Louvre Window ‐ Single Glazed||6.38mm Translucent Laminate||6.2*||0.48*|||||
|Sliding Door||ASCEND Sliding Door ‐ Double Glazed||4mm Clear / 6mm Argon Gap / 4mm Clear||4||0.6||0.63||0.32|
|Sliding Door||ASCEND Sliding Door ‐ Double Glazed||4mm Clear / 12mm Argon Gap / 4mm Clear||3.8||0.6||0.63||0.32|
|Sliding Door||Paragon 2 Lite Sliding Door ‐ Single Glazed||6.38mm ComfortPlus Neutral||4.7||0.38||0.43||0.23|
|Sliding Door||ASCEND Sliding Door ‐ Single Glazed||6.38mm Clear Laminate||6.1||0.63||0.69||0.32|
|Sliding Window||ASCEND Sliding Window ‐ Double Glazed||4mm Clear / 6mm Argon Gap / 4mm Clear||4.5||0.56||0.58||0.3|
|Sliding Window||Paragon Sliding Window ‐ Single Glazed||6.38mm ComfortPlus Neutral||5.2||0.36||0.38||0.23|
|Sliding Window||ASCEND Sliding Window ‐ Single Glazed||6.38mm Clear Laminate||6.5||0.59||0.63||0.3|
|Stacker Door||ASCEND Sliding Stacker Door ‐ Double Glazed||4mm Clear / 6mm Argon Gap / 4mm Clear||4||0.6||0.63||0.91|
|Stacker Door||Paragon 3 Lite Sliding Stacker Door ‐ Single Glazed||6.38mm ComfortPlus Neutral||4.7||0.39||0.43||0.39|
|Stacker Door||ASCEND Sliding Stacker Door ‐ Single Glazed||6.38mm Clear Laminate||6.1||0.63||0.69||0.91|
|Awning||Aluminium Awning Window – Double Glazed||4mm Clear / 6mm air Gap / 4mm Clear||4.4||0.57||0.59||0.04|
|Awning||Alumiere Awning Window – Double Glazed||4mm Clear / 12mm Argon Air Gap / 4mm Clear||4.1||0.56||0.57||1.14|
|Awning||Aluminium Awning Window – Single Glazed||6.38mm ComfortPlus Clear||4.9||0.52||0.6||0.04|
|Awning||Alumiere Awning Window – Single Glazed||6.38mm ComfortPlus Clear||5.3||0.52||0.58||1.14|
|Awning||Aluminium Awning Window – Single Glazed||6.38mm Clear Laminate||6.2||0.61||0.65||0.04|
|Casement||Aluminium Casement Window – Double Glazed||4mm Clear / 6mm Air Gap / 4mm Clear||4.2||0.57||0.58||5|
|Casement||Alumiere Casement Window – Single Glazed||6.38mm ComfortPlus Clear||5||0.51||0.58||0.27|
|Fixed Window||Alumiere Fixed Window – Double Glazed||4mm Clear / 12mm Argon Air Gap / 4mm Clear||3.3||0.67||0.71||0.12|
|Fixed Window||Alumiere Fixed Window – Single Glazed||6.38mm ComfortPlus Clear||4.1||0.62||0.73||0.12|
|Sliding Door||Alumiere Sliding Door -Double Glazed||4mm Clear / 12mm Argon Air Gap / 4mm Clear||3.8||0.58||0.6||1.51|
|Sliding Door||Alumiere Sliding Door – Single Glazed||6.38mm ComfortPlus Clear||4.4||0.52||0.61||1.39|
|Sliding Window||Aluminium Sliding Window – Double Glazed||4mm Clear / 6mm Air Gap / 4mm Clear||4.6||0.57||0.6||2.97|
|Sliding Window||Alumiere Sliding Window – Single Glazed||6.38mm ComfortPlus Clear||4.8||0.56||0.65||0.63|
|Sliding Window||Aluminium Sliding Window – Single Glazed||6.38mm Clear Laminate||6.2||0.69||0.75||1.28|
Deceuninck uPVC Windows
|Awning||Deceuninck uPVC Awning Window – Double Glazed||4mm Clear / 16mm argon / 4mm Clear||2.354||0.45||0.46||0.34|
|Awning||Deceuninck uPVC Awning Window – Double Glazed||4mm Clear / 16mm argon / 4mm LowE Plus||1.75||0.35||0.45||0.34|
|Tilt & Turn||Deceuninck uPVC Tilt and Turn Window – Double Glazed||4mm Clear / 16mm argon / 4mm Clear||2.323||0.45||0.46||0.27|
|Tilt & Turn||Deceuninck uPVC Tilt and Turn Window – Double Glazed||4mm Clear / 16mm argon / 4mm LowE Plus||1.739||0.35||0.45||0.27|
|Sliding Win||Deceuninck uPVC Sliding Window – Double Glazed||4mm Clear / 16mm argon / 4mm Clear||2.629||0.51||0.53||0.8|
|Sliding Win||Deceuninck uPVC Sliding Window – Double Glazed||4mm Clear / 16mm argon / 4mm LowE Plus||1.944||0.4||0.53||0.8|
Its very difficult for a single glazed window, no matter the treatment applied or the thickness to come close to a double glazed window in terms of thermal efficiency. There are many factors that go into a double glazed window:
- Thickness of the 2 glass planes
- Type of windows used
- Gap between the window panes
- Argon or other insulating gas used
Viridian is one of the main glass suppliers in Australia and has multiple products that can be considered for your use case.
Low-e windows are common and they make a significant difference compared to standard clear windows. They go through a process of either (source from Viridian – what-is-the-difference-between-hard-coated-and-soft-coated-low-e-glass)
- Soft coated Low E glasses
- must be incorporated into a double glazed unit as the coating is ‘less durable’ than a hard coated (pyrolytic) coating when exposed to the atmosphere. Soft coated Low E glasses cannot be glazed in single glazed applications but hard coated products such as ComfortPlus™ and EnergyTech™ can.
- Pyrolytic coatings have a long shelf life, whereas soft coated Low E glasses do have a shelf life and will begin to break down if stored for too long without being incorporated into double glazed units.
- Soft coat Low E glasses such as Viridian LightBridge™ or PerformaTech™ have significantly lower U values than hard coated pyrolytic glass types.
- Hard-coated Low E glasses are manufactured online during the float manufacturing process where soft coats are applied by a special offline process at some time after the glass has been manufactured.
Single pane Low-e glass has the coating on the inside and can be difficult to maintain a clear window: https://www.productreview.com.au/listings/oceania-glass
Oceania Glass provide the larger window manufacturers glass and this would often go through Veridian. The table below compares the different glass types and their technical specifications. These don’t take into account the frame’s performance so these are easier to compare against each other.
UV – The amount of UV light the glass blocks out
% Light – is the amount that passes through the glass
|Plain glass||VFloat – Clear||6mm||88||60||5.8||0.82|
|Plain glass + No UV||VLam – Clear||6.38mm||87||<1||5.7||0.79|
|Acoustics||VLam Hush – Clear||6.5mm||87||<1||5.7||0.78|
|Better SHGC + Privacy||Evantage – Clear||6mm||68||30||3.8||0.63|
|Low-e||SmartGlass – Clear||6mm||81||48||3.6||0.70||Same as EnergyTech, toughened, and standard sizing. Branded under smart glass. Sold to 2-3 major window suppliers|
|Low-e||EnergyTech – Clear||6mm||81||48||3.6||0.70||Architectural – not standard size|
|Low-e||EnergyTech – Clear||12mm||79||42||3.6||0.63||Monolithic (not laminated). Toughened different to lamination|
|Low-e + No UV||ComfortPlus – Clear||6.38mm||82||<1||3.6||0.69||Laminated glass – UV + Safety|
|Low-e + No UV||ComfortPlus – Clear||12.38||79||<1||3.5||0.62|
|Low-e + Acoustics + No UV||ComfortHush – Clear||6.5mm||81||<1||3.6||0.67|
|Low-e + Privacy||SolTech – Neutral||6mm||63||41||3.7||0.54|
|JailGuard – Neutral||23mm||56||<1||3.0||0.47|
Thermally Broken Window Frames
Double glazing is important and it will reduce the chance of condensation forming and provide thermal insulation however if the frames aren’t thermally broken then it will mean a transfer of heat or cold through the frame and it can cause condensation on the frame and have a lower overall performance of the window. Think of a thermally broken window as having an insulating material in the middle of the frame stopping the transfer of heat/cold.
This is more of an issue in aluminium windows. Timber and uPVC window frames aren’t impacted significantly by this.
Thermally broken frames are more likely to have benefits in climates with temperatures under 5oC but this needs further investigation in your circumstance.
The cost of thermally broken frames can be significant. There are cases where its 40% more and many manufacturers dont have them as an option.
These can cost around $50 per window. For BAL rated homes they need to be made of one that is BAL rated eg. aluminium. Casement windows may not be able to have ones installed unless you upgrade to fully commercial ones.
For doors, you want to ensure that even if you don’t include them to start with that they are provisioned for ones to be installed in the future.
Theres many types of flyscreens including fixed and retractable ones. Some indicative costs are:
- Standard window flyscreen – $45
- Retractable flyscreen – $2000 for 4m bifold doors
Snapshot of pricing as of Jan 22
|Type||Range||Dimensions||Normal||Double Glazing||Laminated||Hush||Comfort Hush||Notes|
|Casement||Ascend||1555 x 855||660|
|Casement||Paragon||1900 x 811||1550|
|Awning (1 window)||Horizon||1900 x 1000||750|
|Awning (1 window)||Ascend||1900 x 1000||900|
|Awning (1 window)||Horizon||1555 x 855||450|
|Awning (1 window)||Ascend||1555 x 855||650|
|Awning (1 window)||Ascend||450 x 1100||400||500|
|Sliding||Ascend||490 x 1100||640||100mm of glass so not worth doing|
|Stacker||Horizon||2100 x 3600||2950|
|Stacker||Ascend||2100 x 3600||3460|
|Stacker||Ascend||2400 x 3600||3750|
|Stacker||Ascend||2700 x 3600||4500 (3100)||4500 was price previously quoted|
|Stacker||Paragon||2700 x 3600||3300||Same door handle on Ascend but doesnt suit it. Haliday and Bailey|
|Stacker||Paragon||3000 x 3600||3600|
|Sliding Windows||Horizon (standard)||1210 x 860||210||N/A||Cant double glaze horizon sliding|
|Sliding Windows||Horizon (custom)||1210 x 870||230||N/A||Cant double glaze horizon sliding|
|Sliding Windows||Horizon (custom)||1220 x 860||210||N/A||Cant double glaze horizon sliding|
|Sliding Windows||Ascend 25||1210 x 860||500||700|
|Sliding Doors||Ascend 25||2700 x 1500||2000|
|Sliding Doors||Paragon||2700 x 1500||2200|
|Fixed||Ascend||2400 x 1000||930|
|Fixed||Ascend||2400 x 1150||600||1000||3050 Ascend max height|
|Fixed||Ascend 25||2700 x 1150||650||1100|
|Fixed||Ascend 25||3000 x 2000||1800||2200 (just window) + site glazing||8mm toughened|
|Fixed||Paragon||2400 x 1000||600||1050|
|Fixed||Paragon||2400 x 1100||1100|
|Fixed||Paragon||2700 x 2000||3500|
|Pricing below from Roseberry||Normal||Double Glazing||Laminated||Hush Glass||Comfort Hush Glass|
|Awning (1 window)||Ascend||1600 x 900||1130|
|Awning (1 window)||Paragon||1600 x 900||2000|
|Awning (individual glazed colonial bar)||Paragon||1600 x 900||2020|
|Sliding (2 lites)||Ascend||1600 x 900||1010||1180||1080||4mm float glass, veridian. Double glaze, 6mm glass, 8mm gap, 6mm|
|Stacker||Ascend 25||2700 x 3430||failing||4650||5600||5750|
|Stacker||Paragon||2700 x 3430||6700||5700|
|Sliding||Horizon||2400 x 1800||1779||N/A|
|Sliding||Horizon||2400 x 1810||1660||N/A|
|Sliding||Ascend||2400 x 1810||2080||2630|
|Awning (AFFA)||Horizon||450 x 4420||N/A||N/A||N/A|
|Awning (AF)||Horizon||2210 x 450||730||960|
|Awning (AFFA)||Ascend 25||450 x 4420||2090||1764|