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UPVC Vs Aluminium
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UPVC Vs Aluminium – Which One Do I Choose?

What is uPVC?

PVC is short for polyvinyl chloride, a chemical compound of chlorine, hydrogen, and carbon. The U in uPVC stands for unplasticised, which means that it hasn’t softened through the addition of chemicals known as plasticisers. This makes it a durable, low-maintenance building material with superior insulation. UPVC is used to make windows and doors, while it is still fairly new to New Zealand, uPVC became common in the UK during the 1990s and has been used extensively in Europe. 

upvc window koffman

What is aluminium?

Aluminium window frames are constructed primarily from aluminium, a lightweight and durable metal known for its strength and corrosion resistance. Aluminium is the most popular building material for windows in New Zealand. Due to aluminium’s thermal transfer properties, standard aluminium frames contribute to heat loss on cold days and excessive heat on hot days. To combat aluminium window frame’s conductivity and bring excellent thermal insulation to these frames, they should be thermally broken. Thermally broken windows have a non-conductive material inserted within the aluminium frame. This forms an insulating barrier, breaking the thermal bridge between the interior and exterior of the building and disrupting the transfer of heat. By insulating from the flow of heat through the frame, thermally broken aluminium windows significantly reduce heat loss during the colder months and heat gain during the warmer months. 

Aluminium window koffman

What are the benefits of uPVC?

Insulation: 

UPVC can be cheaper than aluminium as uPVC is less expensive to produce and manufacturing has fewer steps, resulting in lower production costs. UPVC is in demand in Europe and they have the manufacturing capabilities and scale of operations, sourcing the best products doesn’t cost a premium.

UPVC is not conductive, unlike aluminium which conducts heat, uPVC has a low thermal conductivity. A low thermal conductivity is an inability to conduct and transfer heat efficiently, which means it is a good insulator and will keep your house warm. 

Multi-Chambered design: 

UPVC has a multi-chambered design. The chambers act as a barrier to heat transfer. The design traps a layer of air within the frame, creating an extra layer of insulation between the interior and exterior of the building.

Double or triple seal: 

UPVC frames by Koffman either come with a double seal or triple seal. A double seal is fitted with two sealing levels. The outer weather seal is inside the frame leg, the inner inside the leg sash. A triple seal is fitted with an outer and inner weather seal along with a third centre sealing level. This enhances air tightness, and improves thermal and sound insulation values. If the windows aren’t of a good quality it can lead to moisture vapour. The seals also help to build an airtight barrier. 

UPVC frames are fully welded removing risk of future leakage at the corners as it is often seen in old aluminium frames.

UPVC frames on the inside of the house are always at room temperature which reduces the build up of condensation. Condensation forms when the surface temperature of a window is colder than room temperature. This typically happens on the cold glass and cold frames. Heat recovery ventilation systems keep house moisture level down thus helping to prevent condensation.

Low E:

These coatings help to reflect heat back into the room while allowing natural light to pass through. By improving the thermal performance of the window, low-E coatings can help to reduce the temperature differential between the indoor and outdoor surfaces, minimising condensation

Durability:

UPVC is a good option for coastal areas as it is resistant to corrosion. Coastal areas are often exposed to high levels of salt in the air, which can accelerate the corrosion and rusting of metal materials like aluminium. UPVC does not rust or corrode when exposed to salt water or salty air. 

Security:

UPVC windows come with a multi-point locking system, which secures the window at multiple points along the frame. 

AluClip:

If you like the price of uPVC but don’t like the look, you can add on Aluclip, clip on aluminium that secures on to the frame to give the look of aluminium windows with almost unlimited colour possibilities. UPVC has the ability to be one colour on the outside and another colour on the inside. 

What are the cons of uPVC?

  • UPVC can have size limitations and does not support bi-folds and triple sliders. In these situations we often mix aluminium systems with uPVC in the same house lot.
  • There can be limited repair options when it comes to uPVC, while repairs can be made on the window, sash, and seals and the glass can be replaced, if there is damage to the uPVC frame, it can be difficult to repair this. 
  • UPVC can have limited colour options however, if you do not like the look of uPVC, the aluclip can be added which gives the look of aluminium and almost unlimited colour options. 

What are the benefits of Aluminium?

  • Slim aluminium frames can maximise the natural light let in as it allows for large expanses of glass, maximising the amount of natural light that enters the interior space. Slim frames give a sleek look. 
  • Aluminium is strong and durable, it has a high strength-to-weight ratio, meaning it is strong relative to its weight. 
  • There are less “size limitations” compared to uPVC.
  • Aluminium windows at Koffman can achieve the same R rating as uPVC windows with thermal breaks and correct recessed installation.

What are the cons of Aluminium?

Aluminium tends to have poor thermal insulating performance as it is a highly thermally conductive material. This means it easily transfers heat. Without proper thermal breaks or insulation, aluminium windows can contribute to significant heat loss or gain, leading to reduced energy efficiency and higher heating or cooling costs.  Nothing is separating the frame from the inside of the house to the outside. Due to aluminium being highly conductive, the metal frame acts as a “path” for the heat to escape from the interior of the building to the exterior, this is why a cold draught can often be felt close to aluminium windows. Due to the high thermal conductivity, aluminium frames are more prone to condensation build up compared to other materials. In cold climates, aluminium frames can become cold to touch, leading to condensation on the interior surface of the window. 

  • While aluminium is naturally resistant to corrosion, it can still be susceptible in certain environments, such as coastal areas with high salt exposure. 
  • Aluminium can come with a higher cost compared to other materials such as uPVC. 
  • Aluminium has a relatively high coefficient of thermal expansion, this means it can expand and contract under significant temperature changes, leading to issues with warping, distortion, or air leakage over time.  Frames are mechanically connected at the corners creating future risk of leakage.
  • Not a good heat insulator, very conductive 

Aluminium windows with a thermal break in the frame and recessed installation can significantly improve the insulation. 

What is a thermal break?

Thermally broken windows have a non-conductive material inserted within the aluminium frame. This forms an insulating barrier, breaking the thermal bridge between the interior and exterior of the building and disrupting the transfer of heat. By insulating from the flow of heat through the frame, thermally broken aluminium windows significantly reduce heat loss during the colder months and heat gain during the warmer months.

Thermal break is usually uPVC section which connects inside and outside aluminium frame. Koffman thermal break is larger than typical local options and it is filled with foam for extra insulation.

Thermally broken aluminium windows also reduce the condensation build up by maintaining a warmer internal surface. 

UV and uPVC

There is a common misconception that NZ strong UV light can damage uPVC. When uPVC first came to NZ, it wasn’t designed to withstand the unique conditions here such as the strong UV rays. This is why uPVC tends to have a bad rep for fading, cracking, or turning yellow under the sun. UPVC has since been developed to suit New Zealand conditions and it has been recognised in NZ standards. At Koffman only UV rated uPVC is used, where colour is required, UV rated vinyl foils are used. Vinyl coatings have 4 layers to make them strong and UV resistant.  

The same technology is used in all cars. Modern cars have no issue with plastic elements fading or cracking as the older cars used to.

Choosing between aluminium and uPVC windows involves considering what factors are best going to suit your needs as both offer advantages and disadvantages. The decisions depend on your specific priorities, budget, climate considerations, sizes and architectural preferences. Whether you choose between Koffman’s uPVC window or thermally broken aluminium windows, you will be getting the best quality windows and doors on the market, keeping your house warm and dry.