Framing a window revolution

Here, Chris Coxon, head of marketing at Eurocell, looks at why the latest frame designs offer self-builders more choice than ever when it comes to windows.

One of the best decisions a self-builder can make is to invest in contemporary, high performance, thermally efficient windows. This stands to reason, as around 20 per cent of heat is lost through these elements. Many choose to go beyond current Building Regulations, which require a whole element U-value of 1.6W/m²K or better or Window Energy Rating (WER) of band C or above.

They do this by choosing a triple glazed window with a U-value of 0.7 or 0.8w/m²K to achieve zero-carbon requirements, and that means there are no net carbon emissions. By choosing a window with an Energy Index of 0 or above means there is no energy loss and it could actually allow solar energy into the house to provide heating.

Opting for a window that is as energy efficient as your budget will allow is therefore prudent, not only because it creates a home that is comfortably warm in winter and cool in summer, it will also save money on heating bills and is as future-proof as possible against further updates to building regulations.

Frame and glass energy efficiency

If you plotted all the innovations in glass over the last 50 years it would highlight something quite interesting. The advent of double glazing provided the biggest boost to thermal performance. However, further innovations never quite achieved the same step change as this initial advance, including low e-coating, gas-filled and the rise of triple glazing, good though they are.

In reality, every new development since the introduction of double-glazing has resulted in incrementally smaller improvements over earlier innovations. Of course, the cumulative effect of all of them is that modern windows are still around 90 per cent better performing than a 50-year old single glazed window.

That’s good news, but it doesn’t get away from the fact that there is unlikely to be another 90 per cent improvement in thermal performance of the glazing and each smaller increase will get ever more expensive. That could be why we aren’t seeing as many triple glazed windows in the UK – simply because the incremental performance benefit compared to the cost doesn’t always make it a worthwhile investment.

So, if performance of glass is reaching the point where incremental improvements are becoming ever more expensive, what options are available? There are now multi-chambered frame profile designs available that are super-thermally efficient. Some products mean a U-value as low as 0.7 can be achieved from a standard argon gas-filled, triple glazed unit, without the need for expensive, esoteric-specification glazing units.

This type of multi-chambered frame design narrows the performance gap to triple glazed windows, while costing around 33 per cent less.

Ultimately, multi-chambered frame designs still allow self-builders to choose standard double or triple glazing specifications. That has the ability to significantly reduce the cost of the windows on a self-build project, while achieving comparable U-values.

Material and sustainability

Sustainable use of materials is a global issue and one that is here to stay. Around 50 per cent of all carbon dioxide emissions in the UK come from buildings and that is the reason why government policy, building regulations and innovation from manufacturers are designed to make construction products more sustainable.

The latest multi-chamber frame designs for windows and doors is no exception and aside from the energy efficiency performance, some feature 50 per cent post-consumer, recycled PVC-U as standard. An intelligent design engineered approach means that this recycled material is concentrated in the central core of the profile, where it is completely invisible in an installed window.

Innovation in frame design has taken the PVC-u window into an exciting new era, with exceptional looks, technical performance, sustainability and cost savings – which is great news for self-builders.