Let's Talk Double Vs Triple Glazing — Is the Upgrade Really Worth the Extra Cost? The Answer: It Might Be Overkill for Your Home
If you're debating whether to make the change from double to triple glazing in a bid for a warmer home and lower heating bills, it really might not be worth it, according to the experts we spoke to — here's why
We're living in an age where home energy efficiency matters more than ever, not just in terms of creating a space that feels warm and comfortable to spend time in, but also one that doesn't cost a fortune to run. It doesn't matter whether you are renovating a terraced house, exploring new kitchen extension ideas for your semi, or building a modern masterpiece from scratch — this is something that applies to all kinds of properties.
Addressing your windows and doors or, more specifically, the type of glass they're fitted with, is one of the best places to start making upgrades, but many people remain wary about the actual benefits of swapping existing double glazing for triple — and rightly so, according to Terry Hill, managing director of glazing specialists KLG Rutland. "If you don’t live in the Outer Hebrides, a modern double-glazing option may be all you need to really feel the difference in your home and your bank account," he says.
If you are considering replacing your double-glazed windows or doors with triple-glazed versions, it is well worth doing your research first; otherwise, you could find yourself paying a huge amount of money in return for little to no benefits. We asked the experts for their views on double vs triple glazing to help you decide.
Terry has been the managing director of KLG Rutland since 2016. The company has over 50 years of experience in designing, delivering, and installing windows, doors, and conservatories.
Is Triple Glazing Better Than Double?
The answer to this is not completely clear-cut due to the fact that there are a number of deciding factors to be taken into consideration, as Edward Stobart, technical sales manager at IDSystems explains. "Triple glazing is not better — unless you need that extra performance to comply with Building Regulations or are planning a Passivhaus standard new-build eco-home.
"Not only does triple glazing increase the cost, but it is also heavier," continues Edward. "The additional weight will place limitations on the size of the glass units that can be produced and the size of the panels, especially for sliding doors. Double glazing has come an awful long way in the past 20 years as developments in glass and frame technology have improved thermal efficiency, performance, and specification options significantly.
"Whilst triple glazing is generally more efficient than the equivalent double glazing, the improvement in energy efficiency in terms of U-values is from around 1.4W/m2K to 1.0W/m2K for triple glazing. An improvement, but nowhere near as significant as the jump from single to double glazing."
Edward Stobart is IDSystems’ technical sales manager and has recently celebrated his 20th anniversary at the award-winning glazing specialists. In that time, he’s worked with thousands of homeowners, offering advice and support on glazing solutions for projects ranging from modest urban extensions to the grandest of Grand Designs television projects.
What Are the Pros and Cons of Double Glazing?
When diving into the benefits and disadvantages of double glazing, it is important to compare it not just to more modern triple glazing, but also to the single glazing it often replaces.
"Compared to single-glazed windows of the past, double glazing is substantially more energy efficient, with overall U-values of around 1.4W/m2K compared to close to 5.0W/m2K for single-glazed windows," explains Edward Stobart. "The addition of a second pane of glass, along with argon-filled cavities, prevents heat loss through the glass, whilst modern thermally broken frames also limit heat loss."
Clearly, then, double-glazed windows have many benefits over their single-glazed counterparts (although aesthetics can sometimes be compromised), but they also have some over triple glazing — mainly in terms of how much cheaper they are, as Terry Hill reveals. "Triple glazing is around 30–40% more expensive than double, making the payback of the initial investment longer," he says.
Then there is the fact that they are more lightweight, making for cheaper and simpler fitting, as well as opening up possibilities for larger units, as Edward Stobart explains. "With triple glazing, you are more likely to need a crane or lifting equipment to support the installation," he says.
What Are the Pros and Cons of Triple Glazing?
If there are so many benefits to be enjoyed by fitting high-spec double glazing, then you could be forgiven for asking what the point of triple-glazed windows is at all.
Rebecca Clayton, a director at IQ Glass, explains its advantages. "Triple glazing adds an extra pane and cavity, which can improve insulation and reduce that 'cold glass' feeling in winter. In real homes, the biggest gains are often comfort and condensation resistance rather than energy numbers alone, particularly on large glazed elevations or exposed sites."
"It is also important to consider the locations where triple glazing works best," adds Edward Stobart. "In Scandinavian climates where prolonged periods of sub-zero temperatures throughout winter are the norm, triple glazing has become the standard in their ultra-insulated and efficient homes.
"For milder climates like the UK, the benefits are less substantial on new-build homes and potentially even non-existent on extensions and renovations of existing properties," continues Edward. "Saving 0.4W/m2K of U-value on sliding doors on a Victorian terrace home extension in London, whilst the remainder of the fabric of the house is relatively inefficient, will likely make almost no difference to saving on energy bills and heating costs."
If this has left you feeling uncertain of why you would ever consider upgrading your windows to triple-glazed versions, it is useful to break down their pros and cons.
Pros of Triple Glazing:
- Better thermal performance: Especially on large glazed elevations and in exposed locations.
- Improved comfort: Glass stays closer to room temperature, so spaces feel less 'chilly' near windows.
- Reduced condensation risk: Warmer inner pane helps in higher-humidity homes.
- Potential acoustic gain: Sometimes improved, though acoustics depend more on glass make-up and airtightness.
Cons of Triple Glazing:
- Cost premium: Triple glazing usually costs more in materials and in the overall system (stronger frames/hardware, handling, and installation logistics).
- Weight and hardware limits: Heavier units can restrict sizes, especially on large sliding doors.
- Slightly lower light/solar transmission: Depending on coatings and specs, triple glazing can marginally reduce daylight and solar gain; in some designs, that’s a benefit, in others, you’ll want a high-transmission spec.
Rebecca Clayton is communications director at IQ Glass. She has many years of experience with the company, who specialise in architectural glazing and installs some of the most pioneering architectural glass technology available today.
Which Type of Glazing Is Right for You?
It seems then, that in the majority of cases, double glazing is the better option, but that doesn't mean there won't be instances where triple is preferable. To avoid making any glazing mistakes you'll later regret, bear in mind that your decision, in the main, should be based on the type of house you live in and its location.
"Where triple glazing is most worth it is on large areas of glazing, colder north-facing elevations, exposed/coastal projects, or low-energy builds where the rest of the envelope is already strong and glazing becomes the weak point," advises Rebecca Clayton. "Where high-spec double glazing can be enough is when the frame is genuinely thermally broken, and the glass specification is optimized with the right low-E coatings and warm-edge detailing."
"If maximum insulation is your goal, triple glazing offers the highest level of thermal performance," adds Terry Hill. "With three panes of glass and two insulating cavities, triple glazing significantly reduces heat loss and enhances security, ideal for exposed locations or colder climates.
"But that extra weight and size costs money," he points out. "There is also a popular misconception that triple glazing massively improves noise reduction over double glazing. There is minimal improvement on this front, and it is acoustic glass that is really needed to help reduce noise. If you are fortunate enough to be able to afford acoustic triple glazing, then this is the ultimate product for both sound reduction and energy efficiency.
"There are currently advancements in triple glazing where the middle pane is similar to the glass used in a smartphone, reducing the weight and size considerably," reveals Terry. "This new product will probably be available to consumers at the end of 2026 and could change the marketplace once again."
FAQs
Can You Double Glaze Old Windows?
Many owners of period homes will still be living with original, single-glazed windows. As a huge source of heat loss, secondary glazing or upgrading from single glazing to double is something homeowners understandably look into. But is adding modern double glazing into authentic frames a viable option?
"You should choose a supplier who can advise on suitable options, and be presented with designs that respect the proportions, glazing bars, and detailing of your existing windows, while ensuring the installation is safe, efficient and fully certified," says Terry Hill.
"Replacing windows or doors in a period property doesn’t mean losing its soul," he continues. "With a sympathetic design and professional installation, you can preserve your home’s historic charm and character."
Where triple glazing really tends to come into its own is when used not just in exposed areas or within highly energy-efficient modern homes, but also when adding in large expanses of glass. If your patio door ideas include oversized options such as a double-height pivot door or swathes of bifolds or sliding doors, it is definitely worth looking into triple glazing.
