You don’t buy windows very often. Maybe once every 20 years or more… That’s why it’s so important to make the right decision for your needs when choosing between double-glazing or triple-glazing units. What is the difference between double and triple glazed windows? Which is the better option for your home?
To answer the above question, we have to refer to new technical requirements for energy efficiency of buildings that came into force in January 2017. Since then, selecting the right windows has become harder. Some people are convinced that triple glazing is better than double glazing in every situation. Others argue that choosing triple glazed windows over the double-glazed ones isn’t always beneficial. Who is right? Is triple glazing better than double glazing?
What is the difference between double glazing and triple glazing?
The main difference – which is not hard to guess – is the number of panes. The glazing unit consists respectively of two or three panes of glass. They are separated by a warm edge spacer that keeps them in a vertical position and the appropriate distance. The space between panes is filled with argon or krypton, noble gases known for good insulating properties.
Typically, the panes used in each glazing unit are the same, but they do not need to be. By using different types of thermal or chemical treatments on the panes, producers make windows for different needs, such as:
- heat retention,
- noise reduction,
- increased privacy,
- increased security.
Is double glazing good enough?
Bearing in mind the new technical requirements for energy efficiency of buildings as well as rising energy prices, you may wonder if double glazing is good enough for your home. And yes, it may be. It all depends on a number of factors, which we are about to discuss below.
Location and climate
The most obvious factor to consider when deciding between double and triple glazing is the location of your home. Depending on the climate and the average annual temperature, buying double-glazed windows may be a good choice. Why? Each pane absorbs some light. It means that double glazing windows are brighter than the triple glazing ones. What is more, double-glazed windows let more heat from the sun in, so the rooms heat up faster. In colder climates, which we definitely face across Ireland, you will benefit more from installing triple glazing units. This is particularly relevant in the case of windows that are not exposed to a great deal of sun during the winter months, and hence, cannot increase the temperature inside.
Under construction or renovation?
Another important factor is the condition of the building. In the case of houses being under construction, it is always worth considering installing triple glazing windows. Usage of modern, energy efficient materials and technologies will certainly prove more beneficial. Due to better insulating properties, triple-glazed windows improve the quality of living and help to save money on heating bills.
Installation of triple-glazed windows in old buildings being under renovation may be challenging. Double and triple glazing windows differ in the depth of the glazing units, making it difficult to fit in existing window openings. Fortunately, this is not a problem for professional installers. Their knowledge and experiences will help you avoid high costs of installation as well as extra renovation works, which you haven’t been prepared for.
Many or few?
There is no point investing in very well-insulated windows if the house is old and poorly insulated as a whole. But that’s not the only case when double glazing windows are a better choice, especially in terms of price. If there are few windows in the building or the windows are small, double-glazed units will turn out more than sufficient.
When to choose a double glazing window?
Although double glazing windows are less effective in terms of thermal insulation, they are still very popular and often chosen. One of the reasons is their price, which is lower than in the case of their triple glazing counterparts. When is it safe to choose a double-glazing unit?
In order to stay within your budget and at the same time obtain the best quality, you can opt for a combination of double and triple glazing windows. Double-glazed units should be perfectly enough for rooms which are used less frequently, or are not kept at a higher temperature. They are also appropriate for rooms located in the more sunny southern part of the house.
A triple glazing window
Double and triple glazing units can consist of the glass panes of the same parameters and have many similarities. It is the thickness of the glazing unit that is important. However, as we can use thicker units in triple-glazed windows, the value also depends on the depth of the window frame and the possibilities offered by the chosen window model. The main differences refer to the enhanced performance and efficiency of the units in terms of:
- Heat retention
As you probably know, double glazing works by having an air gap that is responsible for reducing the thermal transmission of hot and cold air. By adding an additional pane, another air gap is created. This increases the efficiency of heat loss or solar gain.
- Noise reduction
In terms of noise reduction, triple-glazed units may be tricky. It’s because of the middle pane of glass, which can actually increase sound vibration and amplify sound transference. For this reason, for the best results in sound reduction, manufacturers add a pane with a specialist laminated layer (pane covered with sound-absorbing film). It disrupts the soundwaves transmitted through the glazed unit.
- Security
Because of having three instead of two glass panes, a triple-glazed unit is more difficult to break than standard double glazing. The security may be increased by adding a layer of laminated glass to the unit (from the external side of the window). It will make breaking in more difficult for an intruder, as the polyvinyl butyral layer toughens the glazing unit .
Laminated glass has a polyvinyl butyral (PVB) layer of thin plastic between two panes of glass. If it should break, the glass is fused to the layer and therefore stays in place. For this reason, it is highly popular in places where the pane is exposed to mechanical damage. It’s used in skylights or glass ceilings to avoid glass shattering and falling from above.
When to choose a triple glazing window?
Triple-glazed windows are dedicated for energy-saving homes called passive houses. They are also highly recommended in modern buildings. They prove their properties in:
- homes located in a colder climate,
- rooms situated on the colder northern part of the house,
- frequently used rooms, such us: living rooms, dining rooms,
- buildings with spacious or many window openings.
Triple glazing windows should be around 20 to 30% more energy efficient (with U-value from 0.9 W/m2K) than the double glazing ones. However, there are lots of variables that can compromise the result, such as:
- incorrectly spaced gaps between the panes,
- types of gas or coating used as the insulator,
- using of warm edge spacer (composite spacer) inside the glazing unit (to improve U-value of the glazing unit)
This means that it’s possible for some lower quality triple glazing windows to be less energy efficient than good quality double glazing windows. For this reason, you do not always have to choose triple-glazed units over the double-glazed ones, especially if your budget is tight. When choosing the glazing unit, it is important to focus on the Ug parameter (U-value for the glazing unit). The optimal value for the double-glazed units is Ug 0.6 W/m2K, and for triple-glazed units – 0.5 W/m2K. Regarding the complete window, you should focus on the Uw parameter (U-value). The lower its value, the warmer the window is.
Price difference between double and triple glazing
Of course, the window price is a relevant aspect when making a buying decision. Therefore, you want to know the price difference between double and triple glazing. Instead of comparing and contrasting prices of different manufacturers, we will tell you how to check it on your own.
Let’s assume that an ordinary pane costs €70 / m². How big is your window? To make the calculation easier, let’s take a window with standard dimensions of 1100 x 2200 mm into account. Now we need to multiply the cost of an ordinary pane by the square metre of a window. The result is €170. This is the cost you will incur for adding a third pane to your window. The cost of the window will pay off much faster when you compare it to the expenses you would have to bear for heating or electricity.
