I used to think secondary glazing was ugly – but thanks to some expert advice, I am now considering fitting it to my old windows

As one of the biggest sources of heat loss in my home, the original single glazed windows are something my husband and I have often tried to address. We have done everything right – added draught proofing strips and invested in thermal blinds, yet the fact remains that, when you stand near the window, the cold seeping through is more than a little noticeable.

Our cottage is semi-detached and the house next to us also has a bay window. The owners, at some point in the past, replaced the original windows with double glazed versions and, comparing the two, some of the character of our neighbours' house has definitely been lost. Needless to say, replacement windows are something I am keen to avoid.

However, the fact remains that to sit in the loveseat that nestles in the chilly bay window during the colder seasons, is to resign yourself to either gritting your teeth and enduring the cold, or to layer up beneath a mound of blankets.

One alternative to replacement windows is secondary glazing but, having seen some really grim installations in the past, this has never really been a serious consideration. Now, though, I am wondering if things have moved on. Perhaps secondary glazing doesn't have to be ugly. Here's what the experts had to say on the matter.

Does secondary glazing have to be ugly?

Of course not everyone thinks secondary glazing is unattractive, its just that, personally, I have seen some pretty ugly examples. Often these were back in the days when we were renting and looking around older, shabby, properties where the landlords had spent the bare minimum on their maintenance.

'When it comes to secondary glazing, most people remember the rather ugly and impractical options that were widely used in the 1980s – however technology and product design has moved on,' explains Edward Stobart, technical sales manager at IDSystems.

In fact, speaking to the experts, I began to realise that my view of secondary glazing was perhaps a little out-of-date. Just as with many types of windows, all kinds of modern materials are available and no longer are the options restricted to ill-fitting plastic or flimsy metal framed monstrosities that make opening the windows nigh on impossible.

Edward Stobart

A long serving member of the IDSystems team, for the past 20 years Edward has advised and supported self-builders and renovators to identify the most suitable glazing options for their project. He has recently finished a complete renovation and remodel of his own home, transforming a tired 1960s house into a stylish modern family home.

Will secondary glazing ruin the look of my window?

I have to say that, despite discovering that secondary glazing has come a long way in recent years, I was still worried it could ruin the look of my bay – but the experts were quick to point out its benefits, particularly when it comes to aluminium designs.

'Aluminium frames have thin profiles and strength that ensures their popularity,' explains Aaron Adams, customer relationship manager at Clearview Secondary Glazing. 'They can be powder-coated to almost any colour to match existing window frames or the colour scheme of the building.'

'The advantage of aluminium secondary glazing is that it can be designed to fit to the inside of existing windows without compromising on the aesthetics,' adds Graeme Keenan, partner at Heswall Glass. 'Architraves can be included to hide the framing, but still provide access to the existing window.'

'Slimmer modern frames make it less intrusive than older designs, whilst the ability to shape frames to perfectly match the design of existing windows (particularly important on older listed buildings) mean it is still preferable from an energy saving perspective to single glazing on its own,' adds Edward Stobart.

Graeme Keenan

Graeme started in the glazing industry when he was 18, combining it with school and uni. He took over the family business 15 years ago.

What benefits could I expect by fitting secondary glazing?

With the experts reassuring me that secondary glazing need not ruin the appearance of my windows or the kerb appeal of my house, I'm wondering how much of a difference fitting it would actually make.

'It is important to note why (when there are so many high performance double and triple glazed window options) is secondary glazing still a thing,' picks up Edward Stobart. 'Typically secondary glazing is now only ever used in listed buildings or those in a conservation area, where planning restrictions mean that replacing the existing single-glazed windows for modern aluminium, uPVC or timber frames is not an option.

'Secondary glazing is never going to be as efficient as new double or triple glazing because the cavity between the existing windows and the secondary glazing is too large to be optimal and only contains air – a worse conductor of heat than a denser noble gas like argon. It is also less air tight than sealed units meaning it is more susceptible to drafts than new windows,' continues Edward.

All of that said, according to Edward, I could still expect to see some significant improvements in terms of heat loss by fitting secondary glazing.

'Calculating how much would be saved in energy bills is inherently difficult because older period and listed properties tend to be poorly insulated throughout their structure,' explains Edward. 'Depending on the size of the windows and the layout of the property, secondary glazing could potentially reduce energy bills by between 15-20% compared to single glazing on its own.'

Can I fit secondary glazing myself?

I was keen to find out whether or not fitting secondary glazing was something I could do myself. I know that there are window film insulation kits available, designed for DIY fitting, and it turns out that more permanent DIY solutions are also available.

Clearview, for instance, produce flat-packed systems ready for homeowners to fit into place themselves.

'Our systems are easy to install, in most cases supplied fully assembled, pre-glazed and installation ready,' says Aaron Adams. 'We provide comprehensive step-by-step measuring and installation guidance and precise frame profile details.'

FAQs

How much does secondary glazing cost?

After coming to the conclusion that secondary glazing has, indeed, come a long way in the style stakes in more recent years, and adamant that we won't be replacing our bay window, I am now strongly considering this as an option – but how much is it likely to set me back and how does it compare to double glazing costs?

'The cost for secondary glazing will vary depending on the style, size and shape of the existing window,' advises Edward Stobart. 'Typically you would be looking from around £300/m2 (including fitting) but this will vary significantly depending on the complexity of the window design.

'As a comparison, modern double glazed aluminium windows start from around £600/m2 (ex. VAT), including installation.'

'They dramatically reduce the U-Value of the window down to 0.97 and can reduce heat loss by 65%,' points out Greame Keenan.

Is secondary glazing as efficient as new windows?

Obviously secondary glazing is cheaper than replacement windows, but can it ever be as efficient?

'It offers similar benefits to double glazing, with less disruption, but is not as effective a thermal barrier as modern, high performance windows and doors which use argon filled cavities within sealed units for better energy efficiency,' explains Edward Stobart.

'While modern windows are better at preventing heat loss through the glass and frames, their use is restricted on historic or listed buildings.'

While secondary glazing can really help with heat loss, if you are carrying out a renovation project it is still well worth looking to all the different types of glazing – it is possible to have authentic replacement windows made to suit period properties.