The Energy Efficiency Battle: Comparing Double and Triple Glazed Windows for UK Landlords

By 5 min read • March 14, 2024
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Are your energy bills soaring, leaving your profits dwindling? Or perhaps your tenants have reported that the windows in their home are draughty or broken? These are all signs that the windows in your property need to be replaced and require improved insulation.

Unfortunately, the process of replacing windows isn’t as straightforward as it seems. As a landlord, you need to take into account a variety of factors, such as the type of glazing and frame you install, as well as window cost in the UK.

Double glazing is currently the most popular type of glazing used in the UK and has been so since the 1980s. However, in recent years, you’ve probably heard chatter surrounding triple glazing and its benefits. Triple glazing is already widely used in countries such as Norway and Sweden, so you’re probably wondering whether or not it’s worth it for homes in the UK too.

In this article, we’ll discuss what triple and double glazing are, as well as the costs and practical benefits of both. Arm yourself with the knowledge needed to make an informed decision that benefits both your property and your bottom line.

What Is Double Glazing?

Double glazing is when there are two panes of glass with a layer of dehydrated air or inert gas trapped between them. In contrast, single glazing just has one glass pane, hence the name.

Dehydrated air has a relatively lower rate of thermal conduction compared to regular air, which means that heat cannot travel through it easily and therefore it is difficult for heat to escape from your home via your windows. Windows and doors are two of the biggest culprits when it comes to heat loss in homes, so getting double or triple glazing is highly desirable if you wish to combat this.

While air-filled double glazing is more energy efficient compared to single glazed windows, window glazing specialists agree that inert gases tend to be the most effective. Examples of inert gases include argon, xenon, and krypton.

Alongside reducing heat loss, the process behind double and triple glazing also stops moisture from entering between the glass window panes and prevents condensation. Condensation between your window panes is a problem as it not only reduces the efficiency of your windows but can also lead to mould and rot. Mould and rot are detrimental to the structural integrity of your windows and the surrounding building materials, and can also have a negative impact on your health.

What Is Triple Glazing?

As you’ve probably already guessed from the name, triple glazing is made up of three panes of glass, rather than one or two panes. Triple glazing works much the same way as double glazing, except there are now two inert gas-filled (or air-filled) spaces. This helps to make it even more energy efficient and is why it’s so popular in Nordic countries, such as Norway and Sweden.

Thermal expansion in triple glazing is also important to be aware of. In theory, if there is excessive heat build up, the middle pane can shatter. In order to prevent this, the middle pane in triple glazing consists of a toughened safety glass.

Pros and Cons of Double and Triple Glazing

The pros and cons of double and triple glazing tend to be similar, just that those of triple glazing tend to be slightly more extreme. Below we’ve listed a number of pros and cons to help you make an informed decision on whether or not you should upgrade your home.


Improved energy efficiency: Double glazing offers improved thermal insulation compared to single glazing, and thus improves the energy efficiency levels of your home and reduces your heating bills. By replacing single glazed windows with A++ double glazed windows you could save up to £170 per year. Triple glazing is even more efficient than double glazing.

Noise reduction: Double and triple glazing help to reduce external noise compared to single glazing due to their increased thickness. So, if you’re dealing with noisy neighbours, then this could be the solution you’re looking for.

Improved security: Another pro to the increased thickness is that it increases your window’s durability and makes it harder for potential thieves to break into.

Increased home value: Having a property with a high energy efficiency rating is an excellent selling point for potential buyers and so increases your home’s value.

Reduced condensation: The multiple panes of glass in double and triple glazing helps to reduce condensation build up on the inside of windows. Furthermore, the sealed structure prevents the temperature from dropping.

Variety of styles: Modern double and triple glazed windows are available in a wide range of styles, including casement and sash windows. This means you don’t have to compromise on style in order to have a warmer and more secure home.


Initial cost: One of the main disadvantages for both double and triple glazing is the upfront cost, especially if you’re planning to upgrade all of the windows in your property. The average cost to replace windows in a 3 bed house in the UK with double glazing is £4,400 – £7,300. This will vary depending on multiple factors, such as the frame material. Triple glazing is typically more expensive.

Repair costs: Your windows should typically be more durable with double or triple glazing in place, however, it’s still important to consider potential repair costs if something were to happen to your windows. In some cases, the window will need to be replaced entirely.

Potential condensation between panes: If you notice condensation between the panes of glass, then this is a sign that the seal has broken and needs to be replaced. Condensation can lead to mould and rot, which can jeopardise the structural integrity of your window and be detrimental to your health.

Weight: Particularly in the case of triple glazing, the extra weight from the additional panes will require stronger frames or additional structural support. This can increase installation complexities and costs.

Reduced brightness: For triple glazing, some homeowners have reported reduced natural light in their homes due to the glazing unit’s greater thickness. The number of panes in triple glazing can also negatively affect the clarity of vision.

Different types of glass

For both double and triple glazed windows, there are a number of modern glass options available, each with different benefits. We’ll discuss some of the options you can choose from below.

Low-E glass: Low-emissivity (Low-E) glass has a thin transparent coating, which generally consists of a layer of silver or other low emissivity material. This coating reflects infrared energy, making it highly energy efficient.

Toughened glass: This glass type has been heat-treated in order to increase its strength and durability. This glass is a particularly good choice if you’re concerned about your home’s safety.

Self-cleaning glass: For glass that’s in hard-to-reach places then this type of glass could be advantageous. Self-cleaning glass has a unique coating that interacts with sunlight to break down and loosen dirt, making it easier to clean.

Annealed glass: This is one of the most basic glass types used in UK homes. It is formed by allowing molten glass to cool slowly to room temperature. Annealed glass is typically used as a base product to form other glass types.


Overall, both double and triple glazing come with multiple benefits and are probably both worth installing over single glazing (unless you have a period property). Most of the advantages and disadvantages are magnified for triple glazing when compared to double glazing. If your property is in the more northern parts of the UK, then you are more likely to reap the benefits of triple glazing, so it is worth considering despite the higher costs. However, if your property is in a warmer climate, then the advantages of triple glazing might not be as noticeable and so double glazing is likely to be better value for your money

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