The Smart Alitherm 400: Our most popular window, here’s why

Back in January we added the Smart Alitherm 400 window to our collection, manufactured by the industry powerhouse that is, Smart Aluminium. 

As expected, this impressive aluminium window is seriously making waves thanks to its design that’s clearly kept building regulations in mind. 

The Smart Alitherm 400 also features the unique Smart ‘quick-glaze’ beads, saving many installers valuable time and hassle on site. 

With a range of fantastic benefits and features, it’s no surprise that this meticulously designed product has become our most popular window to date. 

Here’s a reminder of the key features and benefits if you don’t already know. 

1- Features Smarts ‘Quick-glaze’ bead system 

One of the main talking points of the Alitherm 400 suite is the ‘quick glaze’ bead, something Smart now offers as standard across the whole Alitherm 400 window and door range.

Most aluminium windows have a bead system that requires on-site fitting and once fitted, requires wedge gasket cutting and inserting on-site. As any window fitter will tell you, this is a laborious and unenjoyable process, especially on aluminium windows. The gasket can often be tight to fit and very time-consuming, especially on larger jobs.

In comparison, the Alitherm 400 quick glaze bead has the gasket already extruded into the bead. This means the beads just need to be quickly and simply tapped in on-site. This not only saves the installer a lot of time but eliminates one of the most unenjoyable aspects of the fitting.

2- Building Regs Approved 

Made with building regs in mind, the Smart Alitherm 400 windows and doors fully comply with all 2022 building regulations. This is a window system that definitely won’t leave you open to error when the building inspector comes knocking.

Whilst the new regulations were rolled out last summer, there still seems to be some confusion over what is acceptable. 

We’d like to reassure you all that the Smart Alitherm 400 range is a safe bet, due to Smart going to great lengths to ensure that the windows will satisfy building regulations in a real-world, sensible application. 

For extra peace of mind, we provide a comprehensive building regulations document that shows real-world U values on popular window designs, along with the various energy ratings you can achieve on both double and triple glazing.

3 – PAS 24 Certified 

You might think that PAS 24 should be a basic requirement for any window these days, and we’d be inclined to agree. 

Nevertheless, window systems have to go through strict testing to achieve this, and the Alitherm 400 has done just that.

If you’re installing on a new build, PAS24 will be a legal requirement (also many extensions will often be specified with it too, although not strictly a requirement yet).

PAS 24 is often specified by architects and from an end user’s perspective, it’s a pretty strong selling tool. Any window or door that can achieve PAS 24 demonstrates that it’s a very strong and secure product, making it an extremely valuable asset.

4 – Fantastic Energy Rating 

Meeting more stricter building regulations means that the Alitherm 400 has very impressive U values. A typical U value on a 1.5m x 1.2m side opening window would be 1.4 with double glazing, or 1.1 with triple glazing.

For an aluminium system, these are pretty impressive figures and not only is this good from a building regulations point of view but it means you can use it as a powerful selling tool, especially with heating costs on the rise and customers looking for ways to help offset their energy bills. 

5 – Large Colour Range 

As with most aluminium systems today, the Alitherm 400 range is available in a stock colour range of white, Anthracite Grey and Black. Lead times vary depending on your supplier, but here at The Trade Village, we’re proud to offer a very fast turnaround of 10 days on stock colours.

RAL colours are also available, either as a single colour or dual colour (different colours inside and out). Another nice addition to the Alitherm 400 range is the option of choosing from the popular Smart Sensations and Alchemy ranges. These offer a range of metallic and anodised finishes that give the windows a much more interesting appearance, in our opinion.

Overall Pros & Cons


  • Fully compliant with changes to document L of the building regulations. 
  • Improved thermal and weather performance. 
  • Brand new quick glaze bead for a simpler, faster and cost-effective glazing process. 
  • PAS 24: 2016 approved for added security. 
  • Unlimited colour choice provided by any RAL colour on top of the 4 stock colour collections. 


  • No slimline version available as of yet. 


So there you have it! A brilliant product with a large range of features and benefits, what’s not to love?

If you’re working on full houses or larger projects, make sure you consider the Smart Alitherm 400! 

For more information or to request a quote, click here. Alternatively, please call us on 01642 309574. 

FAQs about the Smart Alitherm 400 Windows 

What colours and finishes are available for the Smart Alitherm 400 windows?

In addition to the 4 stock colour collections, you can choose from any RAL colours, as well as the choice of a matt or gloss finish.

What’s the current lead time for Smart Alitherm 400 Windows?

For standard stock colours, the current lead time is around 2 weeks. 

What other aluminium windows do you supply? 

As well as the Smart Alitherm 400, we also supply the following: 

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