Triple vs Double Pane Windows: What’s the Difference?
Learn what makes triple-pane and double-pane windows unique and which glass option is best suited for your home.
ByTaeya De Vries
What are Double-Pane and Triple-Pane Windows?
Double-pane windows, also known as dual-pane windows or double-glazed windows, have two panes of glass, many with insulating argon gas between the panes. The additional layer of glass with an insulating gap in between acts as a sound barrier and improves energy efficiency. At Pella, double-pane glass comes standard on all windows.
Triple-pane windows, also referred to as triple-glazed windows, have three panes of glass. Like double-pane windows, there is a gap between panes which can house an insulating gas. The increased insulating air space of triple-pane glass delivers even better energy efficiency and noise reduction. This glass option is an upgrade available on select Pella windows.
Both dual-pane and triple-pane windows can allow for blinds- and shades-between-the-glass as well as grilles-between-the-glass. Tucked in the gap between glass panes, these window fashions are protected from dust, damage and little hands. Additionally, because they are located between panes of glass, the surface of the window remains smooth, making it easier to clean.
Comparing Triple-Pane and Double-Pane Window Costs
When considering window replacement options, cost seems to be top of mind for many people. As you might expect, triple-pane windows are typically more expensive. The additional cost is a result of extra material and a more complex manufacturing process. According to Essential Home and Garden, dual-pane windows usually pay for themselves a little more quickly. However, triple-pane windows typically pay off if you plan to stay in your home for the long run. Not to mention the increased value and comfort that triple-pane windows offer a home.
Energy Efficiency of Dual- and Triple-Pane Windows
When it comes to energy efficiency, both dual- and triple-pane windows are more efficient than single-pane windows. Dual-pane glass insulates almost twice as well as single-pane, while triple-pane glass maximizes energy efficiency. In fact, Pella Lifestyle Series has triple-pane options that are on average 79% more energy efficient than single-pane windows.17
So what makes double- and triple-pane window glass options more energy efficient?
To begin with, a virtually invisible Low-E coating can be applied to all glass at Pella to help reflect heat and keep your home more comfortable by blocking most of the sun’s harmful ultraviolet rays. While both dual- and triple-pane windows feature Low-E glass, three panes of glass block even more of the sun’s ultraviolet rays, helping keep your home more comfortable and efficient year-round.
Another factor contributing to improved energy efficiency is the insulating value of a window. The rating measurement for the overall insulating value of a window is called the R-value. The higher the R-value, the better insulated the window is. In double- and triple-pane windows, there is space between each pane of glass. Inert argon gas can be used between panes of glass to offer additional layers of insulation and help reduce thermal transfer. Since triple-pane windows have more layers, the insulating R-value is better than that of dual-pane windows.
Noise Reduction Benefits of Double-Pane and Triple-Pane Windows
To measure the sound isolation of a window, we use something called the STC rating. STC stands for sound transmission class. The higher the STC rating, the better sound isolation the window can achieve. While completely soundproof windows don’t exist, both double- and triple-pane glass options offer significant noise reduction in comparison to single-pane glass. As described above, the space and gas between individual panes of glass act as insulators, which also help dampen outside noises. Therefore, as you add panes of glass to a window, the amount of noise that can travel through is reduced. In addition, adding panes with different glass thicknesses helps dampen sounds at different frequencies. Three panes of glass with mixed glass thickness will disrupt the most sound waves to reduce noise transmission and achieve the highest STC rating.
Are Triple-Pane Windows Worth the Investment?
While triple-pane windows cost more than double-pane windows, they offer many added benefits, from improved efficiency to sound reduction. When deciding if triple-pane windows are worth purchasing, consider how long you plan to stay in your home. Will you be staying long enough to recoup the investment with energy savings? Also, think about the climate you live in. Triple-pane windows do a better job at reducing thermal transfer, so these might be the best windows for your region if you frequently experience extreme cold or hot weather. The bottom line is this – the benefits of replacement windows with triple-pane glass may be worth the additional cost if you have the right conditions to recoup your investment over time.
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Frequently Asked Questions
While triple-pane windows cost a little more than single- and double-pane windows, they offer many benefits. Energy-efficient triple-pane windows help reduce sound and energy costs. Pella triple-pane windows allow for increased energy efficiency while blocking 86 percent of the sun’s ultraviolet rays.
Yes, triple-pane windows provide better overall performance with an additional pane of glass that improves efficiency and reduces noise.
While completely soundproof windows don’t exist, triple-pane glass is a great way to reduce noise. With three panes of glass and space between panes, sound waves are disrupted and outside noises are dampened.
Triple-pane windows, also referred to as triple-glazed windows, have three panes of glass. There is a gap between each pane which may house an insulating gas like argon. The increased insulating air space of triple-pane glass delivers even better energy efficiency and noise reduction.
Double-pane windows are filled with a gas between the panes of glass. The standard offering is filled with air. There is also the option to upgrade to argon-filled glass, which is a non-toxic odorless gas that offers better insulation because it is denser than air.
Double-pane windows help improve energy efficiency, block harmful ultraviolet rays, reduce noise and offer an additional layer of protection from the elements.
Double-pane windows, also referred to as dual-pane or double-glazed windows, have two panes of glass, many with insulating argon gas between the panes. The additional layer of material, plus the insulating gap in between is what makes them stand out. Double-pane windows help reduce sound and improve energy efficiency.
Glazing refers to the glass installed in the window frame. A window with one pane of glass is called a single-glazed window. Windows with two panes of glass are double-glazed windows. Double- and triple-glazed windows are more efficient than single-glazed windows.
Triple Glazed Windows: Do They Make Sense?
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(Image credit: Green Building Store)
Triple glazed windows are becoming an ever more popular option from today’s windows suppliers – particularly in the aluminium space – but long-standing concerns about the real benefits outweighing the perceived costs are still on homeowner’s minds.
It’s a tricky decision that faces self-builders when they come to specify their final finishes and, as triple glazed windows cost around 20% more than double, why should anyone choose it? Advocates point out that its more about quality and comfort and that self-builders should consider triple glazing for the same reasons they install underfloor heating: it’s just better.
Here’s what you need to consider when weighing up the pros and cons of if triple glazing is worth it.
What is a Triple Glazed Window?
In short, and as might seem obvious, triple glazing contains three panes of glass within a sealed frame, just as double glazing contains two. Between each pane is a pocket of air or inert gas, such as argon; argon is heavier than air and works as an insulator for both noise and heat.
The third pane of glass located half way between the inner and outer panes of double glazing creates two air locks which improves the energy performance of regular double glazing by around 50%.
Energy efficiency is further improved by variables such as the type of air or gas used in the space between the panes, warm edge spacer bars around the perimeter to reduce thermal bridging and different coating on the glass to reduce energy loss from the inside. The frames themselves also have a large bearing on the overall performance (as well as the insulation). Look out for insulated frames that have a good airtightness rating.
Origin’s bifold doors can be chosen with triple glazing for added security (Image credit: Origin)
Is Triple Glazing Better than Double Glazing?
The rough and ready method of comparing the energy performance of windows is to use the U value measurement, just as we do with walls, floors and roofs.
Glass manufacturers have mastered the art of coating and tinting glass with all manner of finishes which can keep the heat in, unwanted sunlight away, reduce glare and even self-clean, too. The net result of this glass engineering means the U values of glazing has been reduced dramatically.
- Single glazed windows can have a U value of around 5.0W/m²k
- Double glazed windows used to score over 3 and can now achieve 1.4 (Velfac have 1.36). As a result of these improvements in the manufacturing process, Building Regulations now insist that any window you install today should have a U value no worse than 1.6
- The Passivhaus standard requires triple glazed windows with a U value of no more than 0.8 but there are some suppliers who claim to achieve just 0.5
The U value demanded for walls is currently less than 0.3 so you can see that windows remain weak spots in the overall thermal efficiency of a building envelope. Hence the tremendous pressure to improve their performance even further.
Manufacturing Improvements in Glazing
Improvements have been brought about by the introduction of:
- Wider cavities between the two glass panes 16mm is the optimum distance
- Low-emissivity coatings being added to the glass to stop heat escaping
- The cavity being filled with an inert gas, usually argon
- Designing out cold bridges, such as aluminium spacers, surrounding the glazed units
Green Building Store offer triple glazing as standard in all of their windows and are specialists in low energy building design (Image credit: Adam Scott c/o Green Building Store)
How Much Do Triple Glazed Windows Cost?
Although triple glazed windows long held the reputation of costing almost double the amount of double glazed, European manufacturers such as Velfac and Internorm are so busy creating triple-glazed windows for their European customers that it’s a bit of a pain to create double glazing for us Brits. As a result, the extra price of the glass can often be measured in the low single percentage points — if at all.
The energy savings from switching from single to double glazing are considerable, but the difference between a U value of say 1.4W/m²k (double glazing) and around 0.8W/m²k (triple glazing) is much less and would account for perhaps 5% improvement in the overall energy performance of a new house. (Windows conventionally account for around 20% of the overall heat loss.) Translate this saving into pounds sterling and you might expect the switch to triple to save you between £20 and £40 a year on heating bills depending on the size of your house.
It doesn’t add up in terms of conventional payback calculations; this is not a scenario in which you’ll see the additional cost of triple glazing ‘paid back’ in 10 to 15 years against the savings made of your energy bills.
However, the increase in energy performance is significant and well known with whole Passivhaus designs (rather than just switching to triple glazed windows in a regular house) boasting energy bills as low as £120 per annum, more than enough to recoup the initial investment after enough years.
Ecohaus‘ Visi Line sliding doors come equipped with high performance triple glazing (Image credit: Ecohaus)
Benefits of Triple Glazing
The key benefits are really to do with comfort. If you insulate the walls, roof and floor of a house, and you ignore the glazing, you end up with cold spots surrounding the windows at night, which cause draughts, draw heat away from you if you sit next to them, and result in streams of condensation running down the panes.
So, in essence, the standard of glazing has to match the standard of the insulation elsewhere in the house, so that the warm wrapping around the house performs consistently.
- Thermal comfort levels: while a double glazed window is perfectly adequate, a triple glazed one is just that much more comfortable, because it hangs onto heat just that little bit better (the surface temperature of a modern, energy-efficient double glazed window is 16°C in a room heated to 21°C where triple glazed can offer 18°C).
- Acoustic performance and noise reduction: double-glazed windows can achieve an acoustic performance in the range of Rw32. This can be improved into the low 40s with some types of triple glazing — the difference on a busy road between a good night’s sleep and a disrupted one.
- Reduced risk of condensation: the lower U values of triple glazed windows helps towards minimising internal condensation issues as the heat is kept inside the building and typically stops the cold external temperature reacting with internal warm air resulting in condensation. (However, the main cause of internal condensation is high internal humidity levels (tumble dryers/wet rooms and lack of adequate purge/ventilation)).
- Can be more costly
- Their heavier frames can damage walls if they’re not properly supported
- They have to be installed correctly, otherwise their performance can be compromised
This self-built Passivhaus has annual energy bills of just £300 and the homeowner praises the house’s comfortable temperature due to the standards in glazing (Image credit: Simon Maxwell)
Considering Window Ratings, Heat Absorption and Solar Gain
Windows behave rather differently to walls and roofs in that, when the sun is shining, they are capable of absorbing heat. In fact, the very best double glazed windows are already capable of being net heat contributors over the course of a heating season. In contrast, triple glazed windows slightly reduce the heat absorption characteristics of a window.
To reflect these complexities, the British Fenestration Rating Council has devised a scheme for the energy labelling of windows, from A down to G. The top rating is reserved for windows that are reckoned to absorb as much heat as they lose, and they include both double and triple glazed windows.
Will Triple Glazing Add Value to my Home?
Bit by bit, we are being encouraged to switch from double to triple glazing. You may not have noticed yet but the pressure is on to improve the energy performance of windows and we are now reaching the stage where mere double glazing will no longer be enough.
With the government increasingly under pressure to reduce carbon emissions and global warming being ever more important in the public’s conscience, properties that reduce energy usage through build design or upgraded features (such as windows and doors) are looked on favourably in this day and age.
(MORE: How to Add Value to Your Home: 20 Genius Tips)
IQ Glass designed and installed structural triple glazing for this home (Image credit: IQ Glass)
Should I Switch to Triple Glazing?
Opinion is divided. Triple glazing is widely used in cold climate countries like Sweden and Norway, and the ultra-low energy Passivhaus standard requires triple glazed windows with a U value of no more than 0.8. To get a window with such a low U value, you have to not only switch to triple glazing but also insulate the frame itself, as well as using more expensive manufacturing techniques — the gas krypton tends to be used, instead of argon.
There are many who argue that triple glazing simply doesn’t make sense in a climate like ours. Triple glazing is more costly to produce, produces much heavier sections and has an embodied energy approximately 50% higher than double glazing.
However, triple glazing advocates tend to argue that crude calculations of initial costs versus U values and energy bills. The big plus to triple glazing is that it adds an intangible comfort factor to life indoors in the colder months which, once experienced, is something most self-builders are willing to pay more for.
Further Innovations in Glazing
Window manufacturer Scheiwiller in Switzerland is producing quadruple glazing (i.e. four panes; three cavities). There are, however, technical problems with simply adding more and more panes of glass: not only does the resulting window become ridiculously heavy, but the additional panes stop light coming through. In fact, in terms of energy efficiency, there may even be a fall-off as the amount of sunlight the window can absorb is reduced.
It is more likely that future developments in window technology will evolve around new coatings, or phase change materials which absorb heat in sunlight and release it at night. Look out for GlassX, produced by another Swiss company, which is already manufacturing a product that does this.
An alternative option that might make more sense is to revisit the traditional practice of drawing curtains across windows after dark. It may be low-tech, in comparison with glazed cavities filled with krypton, but it’s something of a natural British habit and it does cut down on heat loss. Perhaps it’s time we paid attention to improving the heat retention characteristics of curtains and blinds, rather than continuing to engineer glazing units to ever lower and lower U values.
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Mark is the author of the ever-popular Housebuilder’s Bible and an experienced builder. The Housebuilder’s Bible is the go-to hardback for self builders; originally published in 1994, it is updated every two years with up-to-date build costs and information on planning and building regulations, and is currently in its 14th reiteration.
He has written for publications such as Homebuilding & Renovating for over three decades. An experienced self builder, his latest self build, a contemporary eco home built to Passivhaus principles, was created on a tight urban brownfield plot.
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Single, double or triple: how should my windows be glazed?
5/5 – (1 vote)
If you are considering window options for your new home, you may be wondering what you need for better thermal insulation. Is a modern single window enough, or do I need a double window to create the proper “thermal blanket” effect? Is triple glazing a good option or is it just overkill for a new home?
Here we discuss the merits and points to consider in all three options.
Glazing is a glass component in a window frame. How well that glass is sealed into your frame, the type of material, fasteners, and glass thickness all affect how well the window will be insulated.
However, if you’re concerned about a particular material letting in more cold air, don’t. oknaminsk24.by we offer PVC and aluminum window frames that are well insulated inside the frame, minimizing heat loss.
Although this largely depends on the insulation of the frame and the quality of glass you are using, single glazing will not provide the thermal insulation you get with double or triple glazing. This is why the new h2 standard essentially eliminates the use of single glazed windows in New Zealand homes.
Double and triple glazed windows are naturally better insulated. Unlike single glazed windows, they contain air or gas between the panes, which act as a thermal barrier and therefore naturally have a lower U-value (a measure of the heat transfer coefficient). This means less heat leaves the home, which increases your heat source’s ability to efficiently cover a home or room, lowering your overall energy bill.
In the same way, double-glazed windows prevent outside heat from entering the house in summer, resulting in a more comfortable indoor temperature throughout the year.
What to consider with double glazing is the amount of space between the panes and the size of the panes themselves. More space allows more insulating cover to be used, while one thinner panel (about 4mm) and a thicker panel (about 6mm) can suppress noise more effectively.
Triple glazing performs twice as well as double glazing when it comes to thermal insulation and energy efficiency. While double glazing typically has a heat transfer coefficient of 1.5-3.5, triple glazing can go as low as 0.5, which means minimal heat leakage. Effective resistance means less condensation on the glass, so you can maintain better image quality all year round without moisture buildup.
Triple glazed windows are also much more secure and harder to break than single or double glazed options.
So which is better?
The best glazing solution depends on what you are trying to achieve with your windows and the area in which you live. In New Zealand, especially in the colder southern regions, an additional thermal barrier in your window frames may be required during the winter. If you are considering your home as a long-term investment (somewhere over a decade), triple glazing may also be an option, as the investment will eventually pay off in the energy saved.
whether to choose double or triple glazing. News from Light Windows
When evaluating the advantages and disadvantages of double glazing versus triple glazing, many factors must be considered before the differences between the two glazing options can be fully understood.
Unfortunately, this is much more complicated than the fact that two glass panels are used for double glazing, and three for triple glazing, windows from the Light Windows company svetokna. ru can serve as examples, the variety and quality of the services provided by the company will be able to impress even the most knowledgeable customers.
While adding extra glass to a window will undoubtedly lead to huge improvements in terms of thermal efficiency, it will also have other consequences.
To determine which option is best for your property, you need to consider the impact that an additional panel will have on:
- Energy Efficiency
- Pros and cons of a window
We hope this article lays out all the possible implications so that no matter which option you end up choosing, you can make an informed investment decision based on all the most important facts.
What is triple glazing?
Triple glazing consists of three glass panels instead of one or two. The cavity between the glasses is usually filled with an inert gas such as argon, xenon or krypton. Together with an additional panel, this can help reduce noise transmission and increase energy efficiency.
Is double or triple glazing more energy efficient?
The “U-value” measurement is the industry standard for comparing the energy performance of windows and is similar to the “tog” rating that accompanies a duvet. U-values are used to measure the effectiveness of a material as a thermal insulator. The lower the U value, the better the material is as an insulator.
U-values can be applied to windows, walls, floors and roofs. It is calculated by dividing the heat transfer per square meter (in watts) by the temperature difference throughout the building.
Independent studies have shown that triple glazing performs better than double glazing in many ways.
The results of the internal temperature showed:
- Ground air temperature at the insulating glass unit: 1°C
- Ground air temperature next to the double glazing: 11°C
- Ground air level next to energy efficient double glazing: 16°C
- Surface air temperature at a triple glazed window with center panel U value of 0.