Standard aluminium windows cost the least upfront, while uPVC windows typically cost 30% to 50% more but insulate far better. Government figures rate the same double glazing at a U-value of 3.0 in a uPVC or timber frame, 3.6 in thermally broken aluminium and up to 4.8 in standard aluminium. For Perth owner-occupiers facing hot summers and coastal salt air, uPVC usually works out cheaper over the life of the window. Aluminium still suits slim frames, very large glass and bushfire-prone blocks.
This guide compares the two frames side by side, then looks at upfront price and how each one handles Perth’s heat. It explains how close thermally broken aluminium comes to uPVC and how each frame copes with salt air and sun. It also covers design, bushfire rules and environmental impact, and sets out which frame suits which kind of home.
uPVC vs Aluminium Windows at a Glance
uPVC wins on insulation, solar heat and corrosion, while aluminium wins on upfront price, slim frames, natural light and bushfire use. Thermally broken aluminium sits between the two on both price and performance. The table below compares the three frame types with the same double glazing.
| Feature | Standard aluminium | Thermally broken aluminium | uPVC |
|---|---|---|---|
| Upfront price | Lowest | Middle | Middle to highest |
| U-value, double glazed (lower is better) | 4.2 to 4.8 | 3.6 | 3.0 |
| Solar heat gain (SHGC, lower is cooler) | 0.69 | Not listed | 0.61 |
| Visible light through the window | 0.72 | Not listed | 0.65 |
| Coastal corrosion | Finish can pit and chalk | Finish can pit and chalk | Does not corrode |
| Frame size | Slimmest | Slim | Bulkier |
| Bushfire use | Non-combustible | Non-combustible | Combustible |
The performance figures come from two Australian Government sources. The YourHome glazing guide lists the same 3 mm/6 mm air/3 mm double glazing at a U-value of 4.2 in aluminium and 3.0 in timber or uPVC, with SHGC of 0.69 against 0.61 and visible light of 0.72 against 0.65. The NatHERS window factsheet rates air-filled double glazing at 4.8 in a standard aluminium frame and 3.6 in a thermally broken one. A U-value measures how easily heat passes through the whole window, so the gap between 3.0 and 4.8 is about 38% less heat flow. Those numbers explain most of what follows, starting with how they show up on a quote.
How Much Do uPVC and Aluminium Windows Cost in Perth?
Standard aluminium is the cheapest frame to buy, and uPVC typically costs 30% to 50% more for the same opening. Thermally broken aluminium overlaps with uPVC on price, depending on the profile and glass chosen. The table shows Canon Double Glazing’s guide prices for a double glazed sliding window of about 1.8 m by 1.2 m, supplied and installed in Perth.
| Frame type | Guide price per opening |
|---|---|
| Standard aluminium | About $900 to $1,300 |
| Thermally broken aluminium | About $1,400 to $1,900 |
| uPVC | About $1,500 to $2,200 |
The uPVC premium comes from its multi-chamber, steel-reinforced profiles, which take more material and work to make than a simple aluminium extrusion. That extra cost buys a frame that keeps heat out every day it is in service. The YourHome glazing guide notes that energy-efficient windows can reduce peak cooling loads enough to cut the size of air conditioner a home needs by around 30%. A smaller system costs less to buy and less to run, which is where uPVC starts to claw back its higher price. The double glazed windows cost guide explains how a full quote is put together, and the running cost depends mostly on how each frame behaves on a hot afternoon.
Which Frame Keeps a Perth Home Cooler?
uPVC keeps a Perth home cooler because it does not carry heat through the frame the way aluminium does. On a 40°C afternoon, a standard aluminium frame absorbs the sun outside and passes that heat to its inside face, where it warms the room. After sunset the metal keeps radiating stored heat indoors. A uPVC frame, with its chambers of trapped air, stays much closer to room temperature on the inside.
Perth gives that difference plenty of chances to show. Bureau of Meteorology records for Perth Metro show an average of 27.0 days a year at or above 35°C and 4.2 days at or above 40°C since 1994. YourHome estimates that up to 87% of a home’s heat gain comes through its windows. With the same double glazing, a uPVC frame also lets less solar heat through, with an SHGC of 0.61 against 0.69 for aluminium, which is about 12% less of the sun’s heat entering the room.
Canon Double Glazing customers typically report 20% to 35% lower summer cooling costs after replacing standard aluminium with double glazed uPVC, with the biggest change in west-facing rooms. Aluminium makers have answered this problem with a frame designed to stop the metal acting as a heat bridge.
Is Thermally Broken Aluminium as Good as uPVC?
Thermally broken aluminium closes most of the gap with uPVC, but not all of it. A thermally broken frame splits the aluminium into an inner and outer section joined by a strip of low-conducting plastic, usually polyamide. That strip stops heat flowing straight through the metal. The frame is still metal on both faces, though, so it insulates less than a uPVC or timber frame.
The NatHERS window factsheet puts numbers on it. With air-filled double glazing, a standard aluminium frame rates a U-value of 4.8, a thermally broken frame 3.6 and a timber frame 3.0, and YourHome rates uPVC the same as timber. Moving from standard to thermally broken aluminium therefore delivers about two-thirds of the improvement that a fully insulated frame gives. Adding argon gas to the unit brings an insulated frame down to 2.6.
For homes that want slim frames with better performance, thermally broken aluminium is a sound middle ground. Its outside face, however, still faces the same coastal conditions that every metal frame does.
How Each Frame Copes With Perth’s Coast and Sun
uPVC copes better with salt air, while both frames need quality materials to handle Perth’s strong sun. The difference shows up mostly in the finish and the upkeep over the years. These are the three conditions that matter most in Perth.
Salt Air and Corrosion
Salt carried on sea breezes attacks exposed metal and its finish over time. The Western Australian Department of Finance notes that corrosive conditions around Perth can extend several kilometres inland, and it calls for a corrosion specialist on government buildings within 5 km of the coast in the harshest zones. Powder-coated aluminium near the beach can chalk, pit and corrode at the joints. uPVC does not corrode, which makes it the safer choice for coastal suburbs.
UV and Fading
Perth’s sun fades and breaks down finishes on both frames. Aluminium powder coatings slowly chalk and lose colour, especially on west-facing walls. Quality uPVC contains UV stabilisers that protect the surface, but cheap profiles with weak stabilisers can turn brittle over time. In both cases, the quality of the material decides how well the frame ages.
Maintenance Over the Years
Aluminium near the coast needs regular washing to remove salt, plus checks on the powder coat, seals and hardware. uPVC needs only a wipe with warm soapy water and a clear path for the drainage holes in the sill. Neither frame needs painting, unlike timber. Both benefit from a yearly check and a light lubricant on the locks and hinges.
Durability is one reason to choose a frame. The look of the window, and how much glass it can hold, is often the deciding one.
Design, Glass Size and Natural Light
Aluminium wins on design flexibility because it is strong enough to make slim frames and very large panels. That suits floor-to-ceiling glass, wide stacking doors and contemporary homes where the frame should almost disappear. uPVC frames are bulkier because their insulating chambers and steel reinforcement take up space. For standard window sizes in most Perth homes, the difference in looks is modest.
Frame size has a measurable effect on light. The YourHome glazing guide rates visible light transmission at 0.72 for double glazing in an aluminium frame and 0.65 in timber or uPVC, so aluminium lets in about 10% more daylight through the same opening. The NatHERS factsheet also notes that window styles differ in how much of the opening is frame, with casement and awning windows carrying more frame than fixed and sliding ones. Frame material also matters for a reason that has nothing to do with looks, on blocks that border bushland.
Bushfire Zones Favour Aluminium
Aluminium is the safer frame choice on blocks with a high Bushfire Attack Level (BAL), because it is non-combustible and uPVC is not. BAL rates how much ember attack, radiant heat and flame a home could face, and Australian Standard AS 3959 sets the window specification for each level. Parts of the Perth Hills and outer suburbs fall into bushfire-prone areas. On those blocks, check the BAL before choosing any frame.
Research from CSIRO on windows and doors in bushfires links annealed glass in a non-combustible or durable timber frame with BAL-12.5, toughened glass in a non-combustible frame with BAL-29 and fire-rated glass with a non-combustible frame with BAL-40. CSIRO also recommends metal mesh screens with gaps under 2 mm on opening windows to keep embers out. Because uPVC is combustible, the higher levels point firmly to aluminium.
Fire risk is a hard limit for some blocks. For everyone else, the wider footprint of each frame is a softer but growing consideration.
Which Frame Is Better for the Environment?
Neither frame is a clear environmental winner, and the answer depends on how long the window lasts and whether the frame is recycled. Aluminium takes a lot of energy to make from raw ore, but it can be recycled again and again. uPVC saves heating and cooling energy every year through better insulation. It is recycled less often at the end of its life.
A peer-reviewed study in the International Journal of Life Cycle Assessment compared aluminium, timber, aluminium-clad timber and uPVC frames over an 80-year building life. Carlisle and Friedlander (2016) found that expected service life was the most important factor in each frame’s impact. Well-maintained aluminium had the lowest impact, largely because of recycling credits and a long life, and a moderately maintained aluminium frame showed about 68% lower global warming potential than uPVC. The study looked at the frames themselves, so the running energy an insulated frame saves in a hot climate sits alongside those results rather than inside them.
A frame that lasts and is recycled at the end will always have a smaller footprint. With price, heat, coast, design, fire and footprint weighed up, the right choice comes down to the kind of home and how long you plan to stay.
Which Should You Choose, uPVC or Aluminium?
Choose uPVC for comfort and long-term savings, and aluminium for slim frames, large glass or bushfire-prone blocks. The right answer changes with how long you will stay and where the home sits. These are the most common situations.
Owner-Occupiers Planning to Stay
If you plan to stay ten years or more, uPVC is usually the better choice. The lower cooling costs, lower maintenance and warmer winter windows add up year after year. Over that time, the savings tend to outweigh the higher upfront price.
Investment Properties and Short Stays
If you are renting the home out or selling within a few years, standard aluminium keeps the upfront cost lowest. Tenants usually pay the power bills, so the owner sees less of the energy saving. Double glazing in aluminium still improves comfort and condensation over single glazing.
Large Glass Walls and Slim Sightlines
For floor-to-ceiling glass, wide stacking doors or a minimalist look, thermally broken aluminium is the best fit. It keeps frames slim and panels large while closing most of the insulation gap with uPVC. It costs about the same as uPVC for standard sizes.
Coastal and Bushfire-Prone Blocks
Near the coast, uPVC avoids the corrosion that shortens the life of aluminium finishes. On a bushfire-prone block with a higher BAL, a non-combustible aluminium frame is the safer path. If a home faces both, the BAL requirement takes priority.
Most buyers still have a few specific questions once they know which way they are leaning.
Frequently Asked Questions About uPVC and Aluminium Windows
These are the questions Perth homeowners ask most often when comparing uPVC and aluminium windows.
Which windows are better, uPVC or aluminium?
uPVC is better for insulation, cooling costs and coastal corrosion. Aluminium is better for slim frames, large glass, natural light and bushfire-prone sites. For most Perth family homes focused on comfort, uPVC is the stronger choice.
What is more expensive, uPVC or aluminium windows?
Standard aluminium is the cheapest upfront, with uPVC typically 30% to 50% more for the same opening. Thermally broken aluminium costs about the same as uPVC. Over ten years or more, uPVC often works out cheaper once cooling and maintenance costs are counted.
What is the disadvantage of uPVC windows?
uPVC frames are bulkier, so they let in slightly less light and suit very large panels less well. The colour range is narrower than powder-coated aluminium, and the frames are not meant to be repainted. uPVC is also combustible, so it is not suitable at the higher bushfire attack levels.
Why wouldn’t you put aluminium windows on your house?
Standard aluminium frames conduct heat, so they make rooms hotter in summer and colder in winter. Their cold inside surface also attracts condensation on winter mornings. Near the coast, the finish can corrode over time. Thermally broken aluminium reduces most of these problems.
Do uPVC windows last as long as aluminium?
Quality uPVC and aluminium windows can both last for decades. Aluminium frames are structurally long-lived but their finish and seals may need attention sooner near the coast. uPVC lifespan depends heavily on UV stabilisers and profile quality, so the length of the frame warranty is a useful guide.
Is uPVC better than aluminium for noise?
The frame material matters less than the glass and seals. National Research Council Canada research found that an opening window typically rates 3 to 5 points lower on sound tests than the same glass sealed shut, so tight seals are critical. Laminated glass and panes of different thicknesses make the biggest difference in either frame.
Can I get double glazing in aluminium frames?
Yes. Double glazing is available in standard and thermally broken aluminium frames. In a standard frame, the metal still carries heat around the glass, so a thermally broken frame or uPVC gets far more value from the double glazing.
Choosing Between uPVC and Aluminium Windows in Perth
uPVC vs aluminium windows comes down to paying more upfront for a frame that keeps heat out, or less upfront for a frame that is slimmer and fire-safe. You can choose standard aluminium for a short hold, thermally broken aluminium for large glass or uPVC for long-term comfort. Leaving standard aluminium frames in a hot, west-facing room means another summer of heat moving through the metal. With about 27 days a year at 35°C or above in Perth, that heat shows up in every cooling bill.
Canon Double Glazing manufactures and installs uPVC double glazed windows and doors in-house across Perth, and can quote uPVC and aluminium options for the same opening side by side. The guide to uPVC double glazing explains how the frame is built, and you can book a free measure and quote or call (08) 9249 9974.
