Triple glazed windows: Are they right for you?

As homeowners search for methods to reduce their energy bills and boost their home’s insulation performance, triple glazed windows are growing in popularity. 

Renowned for their superior insulation properties, these windows build on the success of their double glazed predecessors by adding a third pane of glass. 

Born in the harsh cold of Scandinavia where warmth and comfort are paramount, triple glazed windows are showing their worth in colder climates – and much of the UK can similarly benefit. 

However, triple glazed windows are costlier than their double glazed counterparts with price increased between 10 and 20% on average. Does this premium justify their superior performance?

Let’s delve into the heart of this question and determine whether the investment in triple glazing is truly worth it.

Everyone is familiar with double glazing, but triple glazing goes a step further by adding a third pane of glass to the formation. 

The result is a triple sandwich of insulation that goes beyond the capabilities of a double glazed window. 

Triple-glazed windows are equipped with three individual sheets of glass, separated by pockets filled with an inert gas, usually argon, but sometimes krypton or xenon. By incorporating an additional pane, these windows boast superior insulation, security and sound-proofing compared with double glazed windows. They’re also typically built with warm edge spacer bars – usually a uPVC bar (although other materials can be used, depending on the manufacturer) that insulates the edges of the window. 

The shift towards more energy-efficient homes in the UK has pushed triple glazing into the spotlight. 

As homeowners consider upgrading, understanding the costs associated with triple glazed windows is essential. In short, triple glazed windows cost 10 to 20% more than double glazing, but the exact figure varies depending on the size and style of the window. 

 Let’s take a closer look at triple glazed window costs.

Size and style of window

First, the size and type of window significantly affect the overall cost. 

• Standard casement window: This is the most common window type, typically hinged at the side and opening outwards
• Tilt-and-turn window: This European-style window can tilt inwards at the top for ventilation and swing inwards from the side for easy cleaning. Its multifunctionality makes it slightly pricier than casement windows. It’s common in ground-floor flats and you might find a wider selection of these windows in triple glazing as they’re so common in Europe where triple glazing is more frequently seen in housebuilding. 
• Sash window: This is a classic design where one or more panels slide vertically to open. Due to the complex mechanisms and aesthetic appeal, they can be more costly than casement windows
• Bay window: This combination of three or more windows protrudes from the property, providing additional internal space. The complexity of this design, combined with the increased amount of material, usually means higher costs
• Acoustic or soundproof windows: These are designed specifically to reduce external noise. They may have variations, including thicker glass or special gas fillings, such as krypton. While they can be pricier, they’re invaluable for homes near busy roads or in noisy urban areas. Triple-glazed windows offer better sound performance than triple-glazed windows, as standard, however.  

Frame material

The frame material also impacts the cost of triple glazed windows, just like any other window type. 

• uPVC: This stands for unplasticised polyvinyl chloride. It’s durable, low maintenance and usually the most cost-effective option for window frames
• Aluminium: Modern and sleek aluminium frames offer a slim profile and a contemporary look. They’re robust and have a longer lifespan than uPVC but come at a premium
• Timber: Offering a traditional aesthetic, timber is among the most expensive window frame materials 

Glazing specification

Like other windows, triple-glazed windows come with a wide range of different types of glass, which affects their price. 

• Gas fillings: Most triple glazed windows are filled with argon. Higher-end options, such as krypton and xenon, are more expensive. These gases are like argon but are heavier and denser, meaning they offer superior thermal and sound insulation
• Low-emissivity (Low-E) glass: Low-E glass is designed to minimise the amount of infrared and ultraviolet light that passes through without compromising visible light. It boosts energy efficiency by reflecting heat back into a room during winter and deflecting external heat in summer. It’s applied as a thin film 
• Glass thickness: Typically, the outer and inner panes might be thicker for increased security or soundproofing. Special coatings, such as Low-E coatings, can also be added to reflect heat back into the room

Acoustic glass: This type of glass can be used for enhanced soundproofing. It dampens and absorbs sound waves, reducing noise intrusion and leakage.

So, what are the benefits of triple glazing? As you might expect, they boast superior thermal and sound insulating performance compared to double glazed windows, but by what margins?

Warmer house

Triple glazed windows offer excellent thermal efficiency, as shown by their superior U-values. A lower U-value indicates a material’s enhanced ability to insulate.

While a standard double glazed window may feature a U-value hovering around 1.6 watts per metre square kelvin (W/m²K), triple glazed counterparts can reduce this figure to as low as 0.6 W/m²K. 

This suggests that a triple glazed window’s ability to mitigate heat loss can be almost three times that of a B or C-rated double glazed window. 

Compared to A-rated double glazed windows with U-values of around 1.2 W/m²K, triple glazed windows are still 40 to 50% more efficient. Triple glazed windows are nearly always A+ or A++ rated, whereas double glazed windows are more typically A rated. 

The better your window insulation is, the warmer your home will be in the colder months and the less you’ll need to heat it. This will reduce your heating bills.

Energy savings

The superior U-value of triple glazed windows directly affects a household’s energy consumption patterns. 

Calculating the precise energy savings brought about by triple glazed windows is complex, but here’s an example:

• If 20% of a property’s heat is lost through the windows and triple glazed windows are 40% more efficient than double-glazed windows, then with an average gas heating bill of £792.35 annually, triple glazed windows might save around £63.20 per year
• This assumes an upgrade from good-quality double glazed windows to triple glazed windows. The savings will be considerably higher if you upgrade from less efficient windows.

While the annual energy savings aren’t necessarily groundbreaking, retrofitting a home with triple glazing alongside other eco home improvements (such as floor and wall insulation) will see greater savings as a combined effort, while making your home more comfortable all-year-round. 

Noise reduction

The design of triple glazed windows, which incorporates three separate panes of glass and multiple air or gas-filled chambers, takes sound insulation to a new level.

Including that extra pane and the gas-filled chambers in triple glazed windows can attenuate external noise by an additional 10 decibels.

In tangible terms, in a home equipped with triple glazed windows, an 80-decibel noise level outside (comparable to bustling street traffic) could be reduced to a sound level more on par with a 30-decibel whisper or quiet conversation. 

Triple glazed windows are around 20 to 30% more effective at sound insulation than A-rated double glazed windows. 

Reduced condensation 

The enhanced thermal performance of triple glazed windows also reduces the risk of condensation by lowering the temperature gradient between the interior and exterior of the property. 

By introducing a third pane and second gap, triple glazing brings the temperature of the interior pane of glass closer to room temperature, which reduces condensation formation and lowers internal humidity levels. 

This is particularly beneficial in homes that suffer from condensation and dampness around windows, also lowering the risk of mould, including the notorious black mould.

Triple glazing, while yielding plenty of benefits, also has downsides. 

Cost

Triple glazing is the next leap in window technology, setting a benchmark for superior insulation against both external temperatures and noise. 

Crafting a triple glazed window involves precision and advanced engineering because it’s essential to ensure that all three panes are seamlessly aligned and sealed. 

Moreover, the choice of gas injected between the panes also plays a crucial role in the window’s performance and, consequently, its price. 

When tallying up additional costs, standard triple glazed windows can come out 10 to 20% more expensive than their double glazed counterparts. 

Environmental factors

The narrative around triple glazing is predominantly centred around its energy-saving capabilities. 

While it’s undeniable that these windows can substantially reduce a home’s carbon footprint over time due to decreased energy consumption, there are upfront carbon costs to consider. 

The production of a triple glazed window is resource intensive. From sourcing raw materials, such as sand, for the extra glass pane to the energy used in moulding, transporting and installing these units, the cumulative environmental impact of producing triple glazing is higher than double glazing. 

Triple glazed windows require more energy, known as “embodied energy”, during the entire lifecycle of a product, from raw material extraction to disposal. The embodied energy of triple glazed windows, owing to their manufacturing process and the use of more materials, is higher than that of double glazed units.

Long-term, triple glazed windows still yield savings. One study from Glassonweb demonstrated that the carbon dioxide (CO2) savings accrued over the entire lifetime of a triple glazed window eventually overtake the CO2 produced during manufacturing. 

In Europe, the study found that the carbon payback period associated with triple glazing ranges from 35 to 76 months. The colder the climate, the faster the carbon payback time is. 

Increased weight

The extra pane of glass and thicker frame of a triple glazed window increases its weight and thickness, meaning they’re unsuitable for thinner or unsupported walls. 

Older walls designed to hold single glass panes may not be suitable for heavier triple glazed units without modifications and strengthening. This doesn’t mean fitting triple glazed units is impossible – there are ways of modifying the window aperture and wall to secure the extra weight. However, this obviously comes at an additional cost. 

Double and triple glazed windows are closely aligned, but triple glazed windows objectively outperform their counterparts in most technical categories. Let’s break this down in detail. 

Energy efficiency at a glance

At the heart of evaluating any sustainable technology is its energy efficiency. As noted, double glazing boasts a U-value of around 1.6 W/m²K, but triple glazing can achieve a far superior 0.6 W/m²K. 

In practical terms, this improvement in insulation can translate to savings on your energy bills. Specifically, switching from double to triple glazing could reduce heating expenses by 10 to 15% annually.

Noise reduction

For those residing in loud areas, triple glazing can significantly cut down exterior noise owing to its third pane of glass and extra gas-filled container. 

Triple glazing is up to 30% more effective for sound insulation than double glazing, which can make a huge difference for those living in noisy environments. 

Balancing cost and climate

Top-notch performance does have its cost implications. Given their complex design and the extra materials involved, triple glazed windows can set you back by about 20 to 30% more than their double glazed counterparts. 

Additionally, triple glazing might be excessive in areas with more consistent climates. The colder it is, the more you’ll get out of them. 

With temperatures in the north of Scotland some 4C to 5C colder than the south, triple glazing will go considerably further. 

While it’s true that triple glazing also maintains cooler temperatures in summer by keeping heat from solar radiation out of the home when the windows are closed, it’s cheaper and easier to cool a property than heat it in the UK. 

So, is triple glazing worth it? It might be a cop-out answer, but it depends on your personal circumstances. 

The primary considerations are how long you intend to remain in the property, the performance of your current windows and the costs of the upgrade. 

A long-term perspective

Looking at home improvements as long-term investments is essential for homeowners committed to their current residence for the long haul. While more expensive initially, triple glazing will pay for itself over time. 

With annual savings of around £60, it might take as long as 40 to 60 years to break even from upgrading a three-bedroom property to triple glazing. 

However, this assumes that you already have double glazed windows. If you have single glazed windows or are considering an extension or new build, then the value of triple glazed windows is considerably higher. Upgrading straight to triple glazing from single glazing would make more sense. 

Moreover, you’ll need to offset the cost of the windows against any uplift in your property’s value. Modern high-performance glazing is critical to obtaining energy certificates and boosting your home’s appeal to buyers. 

Sound insulation

Triple glazing can attenuate external sounds by up to 10 decibels more than double glazing, which makes a massive difference in noisy environments. 

If you’re struggling with external noise from roads, railways, aircraft or busy areas, then triple glazing could make a substantial difference to your overall well-being. It also might make it easier to sell or rent a property in a loud area. 

New builds and extensions

For extensions or new builds, the cost-benefit analysis of fitting triple glazing is more favourable. 

That’s because you won’t have any windows to replace and dispose of, and the labour costs will be lower. 

You may also obtain a better energy rating for the property, which will be beneficial when it comes to selling or renting the property. 

Location

The colder the environment, the more effective triple glazing is at heat insulation. Generally speaking, triple glazing in the colder north of the UK will yield higher energy savings and quicker pay-back times than those in the warmer south. 

This doesn’t exclude other advantages, though. Triple glazed windows still keep homes cooler in the summer, reduce condensation and enhance soundproofing. Moreover, virtually every part of the UK is vulnerable to cold winters and local and regional average temperatures are highly variable. For example, hilly parts of the south are often considerably cooler in winter than sheltered lowlands further north. 

Another consideration here is the location of your property. Properties built on Article 2(3) designated land, such as conservation areas, may not be able to receive triple glazed windows without Planning Permission.

This extends to areas where the local planning authorities have placed an Article 4 direction on the local area, restricting development. Moreover, if you own a Listed Building, you’ll need Listed Building Consent to replace the windows. Failure to obtain it is a criminal offence and achieving permission for double glazing is tricky enough, but less triple.  

It’s not to say you can’t upgrade your windows in these situations, but there’s more red tape and you’ll need to obtain the necessary permissions.

Obtaining high standards of energy efficiency

Homeowners interested in building or renovating homes with exceptional levels of energy efficiency will typically need to invest in high-performance triple glazing. 

Triple glazing is essential to obtain A-rated energy performance certificates (EPCs) and meet the high specifications required for EnerPHit (for retrofitting) and Passivhaus (for new builds). 

The EnerPHit and Passivhaus standards were developed to acknowledge properties built to robust energy efficiency standards, maintaining a near-constant internal temperature in the property with minimal heating required. 

The EnerPHit standard specifies that a property comes equipped with high-performance triple glazing to qualify. 

Triple glazing objectively beats double glazing across virtually every performance metric. For energy efficiency, noise reduction or insulation capacity, triple glazing is often the superior choice. 

However, this performance comes with trade-offs. The initial financial outlay for triple glazed windows is notably higher, and the embodied energy – the total energy consumed in producing and transporting these windows – is also greater than double glazed windows. 

As such, it may take a few years of usage before the energy savings associated with triple glazing outweigh the initial environmental impact. 

Overall, homeowners and builders should weigh immediate costs and environmental considerations against the long-term gains when deciding whether to fit triple glazed windows.