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Triple Glazed Windows vs Double Glazed Windows

triple glazed windows vs double glazed

Triple glazed windows and double glazed windows are becoming quite popular among home owners in South Africa. People want to be more energy efficient and live in a more comfortable home.

Windows of houses are no different from that. The new trend in this window sector is triple glazed or double glazed windows. There are three pieces of glass in every triple glazed window. These are kept aside from one another by using a perimeter space bar. The space bar is designed to reduce energy loss.

The whole unit is then closed tight so that no air or moisture can pass. The principle behind this design is to keep minimum space among the glass pieces to ensure improved insulation and noise reduction.

Noise Reduction

STC rating is the standard for residential sound transmission. There are many factors that influence the rating score of windows.  Some are glass thickness, Space between two pieces of glass etc. An MIT study finds that when other factors remain same, “Triple glazed windows provides essentially the same noise reduction as double glazed.”

So if the noise reduction is the sole purpose of your windows, asymmetric glazing of double glazed windows will be a better choice over triple glazing. Dual pane glazing increases the STC rating better than triple glazing. Glasses with different thicknesses are used for asymmetric glazing. For significant amount of sound reduction, you can use laminated acoustic glass (Laminated material is used to bond two or more glasses)


Insulation and Heat Values

Obtaining energy efficiency is the main reason for using insulated windows. These windows maintain cool and uniform temperature inside. You do not have to use the conditioner all day. Around 20 to 30 per cent heating or cooling charges can be reduced by using better-insulated windows. It is cost effective and economic. Also, these better-insulated windows can make your living space more comfortable one.

The makers of the triple glazed windows are very confident about their product and they declare that the triple glazed windows are 25 per cent better than average double glazed window. There are some important things to look for when buying windows.

They are U- factors and R- Values. These measure the windows ability to obstruct heat to the outside.  According to The National Fenestration Rating Council, the U-factor gives a better understanding of the heat transmission than R-Values.  Lower U-factor values mean these windows are better at keeping heat inside or outside.

Another factor named Solar Heat Gain Coefficient (SHGC), is used to measure the amount of heat from direct sunlight that is blocked by windows. A lower number indicates better heat blocking.

Cost of Triple Glazed Windows and Double Glazed

While installing new windows, people mostly think about the cost and comfort. Triple glazed windows are slightly more expensive than the double glazed. For an average sized window, you will have to pay a bit more for the triple glazed one. With Triple glazed windows installed, you can save 3% of the yearly heating bills. Also, it will make your living space much more comfortable.

You should also consider getting a quote for isotherm ceiling insulation. Roof insulation also has a huge impact on heating a cooling bills. The cost of triple glazed windows and ceiling insulation will pay itself off very quickly.

Other Considerations: Light, Framing, Installation, Security


Providing natural light is one of the main functions of the windows. For reducing the amount of solar heat gain through the window, Low_E coatings are now included in the inner part of the window. These coatings block the infrared radiation of the solar rays and reduce the heat gain.

The producers also insist that Low_E coatings are designed in a way that maximizes the transmission of visible light through the window while blocking the heat producing rays. Some people disagree with their claims. They believe Low_E coatings in the double and triple glazed windows darken the room.

Different rooms need different coating according to their exposure to the sun. However, different coatings are of different colors. So it is better not to use two different coated windows side by side. The difference might be easily noticeable.


For windows frame is necessary. You must have considered the cost of frames. Vinyl framed window is the cheapest among the triple glazed. The colours are limited. They do the well in terms of insulating and durability. However, these are a bit bulky and do not look well. However, these usually come with limited lifetime warranty and also the cost of maintenance is lowest.

Fiberglass frames are another good option. The durability of these are remarkable and they last a lifetime. Also, maintenance requires very little effort and is good looking when compared to vinyl frames.

One drawback is that these are expensive and could cost you 50% per cent more than vinyl frames.  Another main benefit of fiberglass frames is these are paintable. You can colour them up according to your wish. Also, there are different standard shades are available to choose from.

Wood frame and triple glazed windows are the most expensive combination. If you are looking for a traditional look, this combination is the best. But you have to be very careful with this because this requires regular maintenance.


For a good thing, you have to do some hard work. Triple pane windows are a bit difficult to install compared to double glazed. They are heavier and wider. It is not easy to wash them because of the significantly heavier sash.

The width of the frames is also a problem. It is not easy handling these and professionals are needed for the installation. Some re-modelling works might be necessary in some cases.

Home Security

Beside all other functions, triple glazed windows also increase the protection of the house. Additional strength is added in the windows with triple panes installed. It creates a hindrance for intruders.

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