The choice of window materials, configurations and styles on the market today can be overwhelming. In this article, we compare several popular window types and explore 5 key advantages of timber-aluminium composite windows. 

What is a composite window?  

Aluminium-clad timber composite windows – often referred to simply as ‘composite windows’ - are timber frame windows clad in a protective powder-coated shell. They are designed to maximise the benefits of both materials. Composite windows offer an excellent compromise between the performance, warmth, and classic charm of timber, and the contemporary appeal of aluminium. 

But composite windows aren’t the only choices on the market. What are the alternatives?  

UPVC windows

Are composite windows better than uPVC? 
UPVC windows are usually cheaper than composite windows. They are also lightweight and easily customisable. That said, timber composite windows easily outstrip their uPVC alternatives for thermal performance and have a much longer lifespan than uPVC windows. Energy savings over this period make timber composite windows the more cost-effective option long term.  UPVC windows are also difficult to repair and usually need replaced if damaged. 


What’s the difference between timber and timber composite windows?
Timber has been the material of choice for window manufacture for generations, and many timber windows are still in use that are more than a century old. Like aluminium, wood is much stronger than uPVC (which requires a metal core to provide the necessary structural support). Wood acts much better as an insulator than either aluminium or uPVC. However, poor quality products produced in the building booms of the 50's and 60's made the arrival of "maintenance free" aluminium and later uPVC seem very attractive.

All-Aluminium windows

What about aluminium windows?  
Aluminium is a stronger material than uPVC. All-aluminium windows are often used for their thin sightlines. Attractive, powder-coated aluminium also adds more kerb appeal than uPVC and is more likely to add value to the property. Most aluminium window suppliers offer finishes in any RAL colour, affording great versatility of design and real aesthetic appeal. Advantages of aluminium windows over all-timber models include: 

A more contemporary look 
No priming, sanding or subsequent painting 
Low maintenance 
No warping, rotting or movement issues 

However, whilst all-aluminium frames are strong and light, aluminium is a very poor insulating material. In fact, as a raw material, timber is around 800 times more effective as an insulator than aluminium. Obviously, aluminium windows are not typically made of solid metal, but even with multi-chambered extrusions and thermal break layers, aluminium is still a poor relation where thermal performance is concerned. 

An impressive material: laminated timber is both durable and a high-performing insulator

Timber-Aluminium composite windows 

Timber-aluminium composite windows provide the best of both aluminium and timber. 

The highest quality composite windows are made from laminated or ‘engineered’ timber, a process that enhances frame durability and makes the windows much less prone to movement than pure timber frames. The low thermal conductivity of wood makes it by far the highest-performing insulator of frame materials on the market.  

Although aluminium cladding does not contribute directly to thermal performance, it can allow for the use of deeper glass units, which provide further performance benefits. Alu-cladding protects the external timber, the whole window is more durable than the all-timber option. 

All-Timber windows

Timber has been the material of choice for window manufacture for generations, and many timber windows are still in use that are more than a century old. Like aluminium, wood is much stronger than uPVC (which requires a metal core to provide the necessary structural support). Wood acts much better as an insulator than either aluminium or uPVC. However, poor quality products produced in the building booms of the 50's and 60's made the arrival of "maintenance free" aluminium and later uPVC seem very attractive.  

So, Why Choose Composite Windows?


Outstanding performance is an obvious reason to choose composite windows.  

With U-values in the region of 0.8 W/(m²K) or better (and some as low as 0.6 W/(m²K)), our triple-glazed composite windows and doors are significantly better performers than aluminium or uPVC models. Several of our models are suitable for use in Passive House and EnerPHit projects, meeting stringent criteria for performance and comfort for use in truly energy-efficient homes. 

Put simply, timber-aluminium composite windows are unbeatable for performance. 

You can read more about the unique elements that make a window truly thermally efficient here

Why should thermal performance be central to your choice of windows?  

Firstly, for comfort. When you choose high performance alu-clad timber windows, you can expect fewer draughts, a warmer inside glass pane temperature, significantly less heat lost through windows and doors - and a generally more pleasant living experience.  

Secondly, to save energy - and money. 


Over their lifespan, the superior thermal performance of high-performance composite windows will significantly lower your projected energy usage

With alarming increases in energy prices and an ever-growing emphasis on low-carbon building, the energy efficiency of composite windows only continues to grow in importance as time goes on. 

Installing high-performance triple-glazed composite windows is a well-established criterion of Passive, EnerPHit and other low-energy building standards – and a key contributor to the overall thermal envelope of your home.

Sustainability is also a key factor to consider here. 

The components, construction processes and waste associated with composite vs. other windows are all worth considering. UPVC windows are made from fossil-fuel-based plastics, implicate high emissions during manufacturing and are difficult to recycle.  

By contrast, our products are made only from FSC and PEFC-certified timber - both renewable and biodegradable. Aluminium can be completely recycled and the production methods and waste materials from producing composite windows are much more environmentally friendly than windows and doors made from uPVC or Aluminium. For example, sawdust produced from the manufacturing process is used for heating. 

You can read more about the environmental impact of wood vs uPVC windows here. 


Can you paint composite windows? Are they customisable?  

Yes. The best composite windows use high-grade powder-coated aluminium, typically considered to be the highest quality finish for an aluminium window. As well as being low-maintenance and weather resistant, alu-cladding can be finished in any RAL colour. You can specify textured finishes, or marine grade powder-coating for properties in coastal or exposed locations.  

Internally, the timber frame can again be finished in any RAL colour or in an attractive lacquer to highlight the beauty of natural wood. You can have distinct colours internally and externally – known as dual colour finish.  

Composite windows offer unrivalled stylistic options. Your order is completely bespoke - from the glass type and colours you choose down to the window mechanism. Hinge systems can be configured in several ways. The frame dimensions, thickness, shape, and opening system of your products are all bespoke to your order.  

Composite windows are the perfect aesthetic compromise between sleek aluminium and warm, characterful wood. 


Are composite windows worth the cost? 

To be clear: alu-clad timber windows will set you back more than most other window types on the market. That said, you can expect the initial investment in triple glazed composite windows to be recouped in the long term – and more quickly than by any other inferior window type. This occurs because, over the course of their lifespan, energy efficient windows will lower your overall energy usage significantly – and implicit in lower energy usage is lower cost.  

Further: the value added to your home by composite windows easily outstrips any feasibly added by a cheap uPVC installation. 


How long do composite windows last? There is no set lifespan, but you can expect your composite windows (if properly maintained) to have a lifecycle of up to double that of uPVC windows.

Composite windows are much easier to repair than uPVC models. A damaged uPVC window will usually need replaced, whereas undertaking minor repairs to either timber or aluminium is relatively simple and will prolong the anticipated lifespan of your windows.  

Laminated timber is a much more robust material than uPVC or aluminium. Our products come with laminated glass as standard for glazed entry doors and multiple locking points to both windows and doors. Forced ingress is extremely difficult due to the solid and unyielding nature of the timber - all our composite products conform to PAS 24:2016 enhanced security performance requirements for doors and windows in the UK.  

So, to summarise. Why should you choose composite windows and doors?  

These are visually stunning, versatile, and entirely bespoke products. High-performance composite windows and doors are a key part of any low-energy building project – but in choosing performance with Norrsken, you’ll never sacrifice style or aesthetic freedom.  

With robust hardware and made from durable laminated timber, our products are built to last and to give you complete peace of mind about the security of your home. As the building industry continues to tend towards ever-tighter standards for thermal efficiency, superior composite windows will help to lower your emissions - and raise the standard of your build - for years to come.  

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