What is secondary gazing? Put simply, it’s an alternative to replacement windows – a supplementary layer of plastic or glass installed on the inner side of your home’s windows. Fitting secondary solution on the room side of your existing windows creates a thermal barrier in the middle. This helps prevent precious heat from leaking out. Secondary glazing is often the preferred option for historic homes where (for planning and conservation reasons) it might not be possible to switch single-glazed windows for double-glazed.

In the right property, secondary glazing has the potential to help you save money on energy bills. Experts at Clearview Secondary Glazing estimate that as much as 20% of the heat you generate can be lost through single-glazed windows (windows that have a single pane of glass). This could save you 10% on your utility bills according their experts.

‘It provides the ideal solution for projects where it’s essential to retain the integrity and provenance of existing windows, yet where there’s a requirement to improve thermal efficiency,’ says Lisa Morton, director at Architectural Bronze Casements. If maintaining the character of your period property is a top priority, then secondary glazing would be the way to go.

Image credit: Future plc/Heather Hobhouse

Various solutions fall under the umbrella term, ‘secondary glazing.’ These range from sheets of plastic to panes of glass fitted within timber, or UPVC or metal frames on the room side of your window.

‘This sort of glazing involves having a fully independent window installed on the room side of an existing window,’ says Dave Mechem, director of inspection and assessment at RISA. Various types are available, depending on your budget. ‘In some cases, homeowners choose secondary glazing as a temporary option. For example, to prevent draughts coming in in the winter months.’

Permanent solutions are typically used in historic or listed homes, where upgrading to double-glazed units often isn’t an option.

Image credit: Architectural Bronze Casements

These are the main types of secondary glazing you’ll come across, but it’s always worth  speaking to a specialist.

DIY systems can range from transparent plastic sheets attached with magnets, to full windows that are screwed into place. This type of setup is easy to remove, which makes it the ideal option in scenarios where a temporary solution is needed to keep winter draughts out.

Depending on where the window is in your house and how often you typically need to open it, fixed or openable secondary glazing designs are available. Choose lift-out secondary glazing, for instance, for windows you don’t need to open as often.  Otherwise, the whole sheet may need to be removed for you to access the original window.

Consider the material options on offer. These range from economical plastic solutions to higher-spec ranges with metal or wood frames. ‘Bronze secondary glazing is a fully independent window system installed to the interior of an existing window. It can either be openable, part removable or fixed,’ says Lisa Morton.

For homes with sash windows (formed of moveable panels that slide over each other to open), there are various opening configurations when it comes to your secondary glazing. Hinged setups operate like casement windows, and swing into the home rather than outward, while horizontal and vertical sliding secondary glazing solutions are also available.

‘Our opening units are usually side-hung,’ says Lisa Morton. ‘These allow access to the external window for cleaning and ventilation purposes.’

Image credit: Future plc/Simon Whitmore

Look at the pros and cons of secondary glazing before deciding whether it’s right for your home.

Image credit: Future plc/Heather Hobhouse

Experts estimate that double-glazing is roughly twice as effective as secondary glazing when it comes to minimising heat loss. So if you’re looking for ways to keep your house warm, secondary glazing will never achieve the same thermal performance as a primary glazed solution.

Double glazing could offer better value if you aren’t restricted by planning rules. It’s likely to be more expensive in the short term, but you’ll save in the long term and your energy bill savings over the years will help offset the initial outlay for supply and installation.

But if your main goal is to cut down the sound of traffic from a busy road outside your house, secondary might just have the edge. ‘For noise reduction, secondary glazing is much better than double glazed,’ says Andrew Smith from City Sound Glazing.

Image credit: City Sound Glazing

These are the factors to consider before deciding whether secondary glazing is the right choice for your property: