When it comes to improving the energy efficiency of your home, there are a few different options available to you. Double glazing and secondary glazing are two of the most popular methods used to improve a home’s thermal and acoustic performance. So which is better?

Double Glazing vs Secondary Glazing

What is Double Glazing?

Double glazing is a type of window that consists of two panes of glass separated by a small air gap. This air gap acts as an insulator, trapping heat inside the home and keeping cold drafts out.

What is Secondary Glazing

Secondary glazing is a type of window that consists of an additional pane of glass added to an existing window. Like double glazing, this extra pane of glass helps to insulate the home and improve its energy efficiency and block out noise.

Secondary Glazing – DOS Glass Replacement

Which is Better?

There are a few key differences between the two types of windows that you should consider before making a decision.

Thermal Efficiency

Double glazing is generally more thermally efficient than secondary glazing. This is because the two panes of glass in a double-glazed window are separated by a much larger air gap than the pane of glass in a secondary-glazed window. This allows for less heat transfer and makes double-glazed windows better at insulating your home.

Noise Reduction

Both double glazing and secondary glazing can help to reduce noise levels in your home. However, there is a misconception on the internet that secondary glazing is better at noise reduction than double glazing. In reality, secondary glazing doesn’t come close to the noise-reducing capabilities of a fully sealed double glazed unit.


Double glazing is typically more expensive than secondary glazing. This is because you are replacing the entire window with a double glazed unit – compared with secondary glazing which just involves adding an additional pane of glass to an existing window.


One of the biggest advantages of secondary glazing is that it can be installed without having to replace your existing windows. This makes it a much less disruptive and cheaper option if you’re looking to improve the energy efficiency of your home. Double glazing, on the other hand, requires the installation of new windows – which can be a much more disruptive process.

Which One Looks Better

Double glazing looks much better than secondary glazing and have a more streamlined look which can be made to match the aesthetic of your home perfectly. Secondary-glazed windows, on the other hand, can look quite bulky and out of place, you also get the unavoidable “double reflection” effect when viewing the window glass at certain angles.

double reflection from secondary glazing
double reflection from secondary glazing

Ease of Use

Double glazing operates just like any other window. You can open and close them with no fuss, and they’re easy to clean. Secondary glazing, however, can be more difficult to use. The additional pane of glass can make it clumsy to open and close your window, and cleaning the windows can be a bit of a pain.


The lifespan of a double-glazed window is typically between 20-35 years. The lifespan of secondary glazing will depend largely on the quality of the installation and the materials used. However, it is not uncommon for secondary glazing to last 10 years or more.


Double glazing is the better option if you’re looking for improved thermal efficiency and noise reduction. Secondary glazing is a cheaper and less disruptive option but doesn’t offer the same level of performance. Double glazing also has the advantage of being easier to use and having a longer lifespan. So, there you have it – a comparison of double glazing vs secondary glazing. We hope this has helped you to make an informed decision about which type of window is right for your home