Double, triple, and secondary glazing have advantages and disadvantages, so choosing between them depends on your circumstances.
The term double glazing refers to a sealed unit consisting of two panes of glass with a space between them, typically filled with an inert gas, such as argon. This gap creates an insulating barrier which reduces heat transfer and sound transmission. They offer several advantages for the homeowner:
- Energy efficiency: The most significant benefit of double glazing is improved energy efficiency. The insulating barrier reduces heat loss in winter and heat gain in summer, leading to lower heating costs.
- Noise reduction: Double glazing effectively reduces external noise, making it an ideal choice for homes near busy roads, airports, or urban centres.
- Condensation reduction: The insulating gap minimises condensation on the inner pane, reducing the risk of mould and dampness.
- Enhanced security: Double glazed windows are more robust and harder to break than single-pane windows, offering an additional layer of security.
- Property value: The energy efficiency and noise reduction benefits of double glazing can increase the value of your property by up to 10%.
- Aesthetic: Double glazing is often considered to be more visually appealing, enhancing the overall appearance of a property.
There are, however, some disadvantages to consider:
- Limited repair options: As they are sealed units, if one of the panes gets damaged or the seal fails, the whole unit may need to be replaced.
- Trapped heat in summer: While double glazing is effective at keeping heat in during winter, it can also trap heat inside during hot summer months; proper ventilation using trickle vents and shading can help alleviate this issue.
Triple glazing involves using three panes of glass within a window unit. This design significantly enhances a window’s insulation properties, trapping more heat inside a building and keeping the cold out.
It’s particularly effective in colder countries, such as the Baltic regions, where retaining heat is crucial. Triple glazing is also beginning to make a big impact in the UK, with updated building regulations under the government’s Future Home Standard project becoming mandatory in 2025. These updates will require new builds to produce 75–80% less carbon emissions than homes built under the current regulations and could include triple glazing as one of the energy efficient measures.
Triple glazed windows offer homeowners a number of advantages over double glazing.
- Improved insulation: The most significant benefit of triple glazing is its superior thermal insulation. The extra pane of glass, along with the gas-filled spaces between them, greatly reduces heat loss, making your home more energy-efficient.
- Noise reduction: Triple glazed windows generally offer excellent sound insulation. They effectively reduce external noise, making them ideal for homes in noisy environments.
- Reduced condensation: The improved insulation properties also reduce the likelihood of condensation forming inside the window, which can be a problem with double glazing in very cold weather.
- Increased security: The additional pane of glass makes these windows more difficult to break, offering enhanced security compared to single or double glazed windows.
There are also a few drawbacks to triple glazing.
- Cost: Triple glazed windows cost between 10 and 20% more than their double glazed counterparts; however, some suppliers offer free or discounted triple glazing upgrades.
- Weight: The additional pane of glass adds extra weight – up to a third more, which can be a consideration in some installations. This may require reinforced or more robust window frames.
- Light reduction: With an extra pane of glass, there can be a slight reduction in the amount of natural light entering the room.
- Challenging for repairs or replacements: Repairing or replacing a triple glazed window can be more complex and costly than a double glazed one.
Secondary glazing involves attaching a separate pane of glass or plastic to the inside of the existing window frame using a magnetic strip with an air gap between the original window and the secondary glazing. It’s particularly useful for listed buildings or those within conservation areas, where alterations to the property’s external appearance are restricted.
Although generally less efficient than double glazing, secondary glazing provides improved thermal insulation and noise reduction. It also has three other advantages:
- Installation: Secondary glazing can be installed as a DIY project or by a professional. It is generally more straightforward and quicker to install than double glazing.
- Cost: Secondary glazing is generally cheaper than double glazing, but it may not provide the same level of long-term energy savings.
- Acoustic insulation: It is generally accepted that secondary glazing can offer good sound insulation, in some cases better than double glazing.
If you’re considering installing secondary glazing, there are some disadvantages to factor in:
- Reduced natural light: By adding an extra layer to your windows, secondary glazing can reduce the amount of natural light that enters your home. This may make your living spaces feel darker and less inviting.
- Ventilation issues: Adding an extra pane can limit the ability to open and close windows easily, potentially reducing airflow and ventilation within the home. This can be particularly problematic in rooms with high humidity, such as bathrooms and kitchens.
- Condensation: Secondary glazing can lead to condensation forming between the primary and secondary panes, especially if the installation is faulty. This can reduce visibility and contribute to the growth of mould and mildew.
- Cleaning and maintenance: Having an extra pane can make cleaning and maintaining your windows more challenging, as you need to consider both the primary and secondary panes.
- Aesthetics: Adding a second pane can be visually less appealing than double glazing, as it may not be as neatly integrated into the existing window frames. It can also create a “double reflection” effect that some people find distracting.