When building a home, selecting the right glazing is a major investment. So if triple glazed windows are something you are considering, here is our advice to help you decide whether they are worth it or not.
Triple glazed windows have become an increasingly popular option offered by today’s window suppliers – especially aluminium windows. However, many homeowners still have real concerns about whether or not the benefits outweigh the perceived costs of triple glazed windows.
Self-builders are faced with this tricky decision when trying to decide on their final finishes. Also, why should anybody choose triple glazed windows since they are about 20% more expensive than double glazed windows? Advocates point to the fact that it is more about comfort and quality and that triple glazing should be considered by self-builders for the same reason that underfloor heating is installed: it is simply better.
The following factors need to be considered when you are weighing the pros and cons of whether or not triple glazing is actually worth it.
What Are Triple Glazed Windows?
It may seem obvious, but briefly put, there are three panes of glass contained in triple glazed widows inside of a sealed frame, just like there are two panes of glass contained in double glazed windows. Between each pane of glass, there is a pocket of inert air, like argon, or air. Compared to air, argon is heavier and insulates against both heat and noise, thus introducing soundproof windows.
The third pane of glass is situated in the middle of the outer and inner double-glazing panes to create two air locks. This helps to improve regular double glazing energy performance by about 50%.
Energy efficiency is improved even further by such variables as various glass coatings that reduce the amount of energy lost from the inside, warm edge space bars located on the perimeter to reduce the amount of thermal bridging, and the type of gas or air that is used in the space in between the panes of glass. The actual frames also have a significant impact on the window’s insulation and overall performance. Look for insulated frames with good airtightness ratings.
Are Triple Glazed Windows Better Than Double Glazed Windows?
To compare windows’ energy performance, one rough and read method is using the U value measurement. It is the same thing that is used for roofs, floors, and walls.
Glass manufacturers have been able to master the art of tinting and coating glass using all different kinds of finishes to self-clean, keep away unwanted sunlight, and keep in the heat. This glass engineering results in a dramatic reduction in glazing U values.
Single glazed windows have about a 5.0W/m²k U value.
Double glazed widows scored a 3 in the past but are now able o achieve a 1.4. This is due to the fact that manufacturing processes have improved. Building Regulations now required that all windows installed these days have a U value that is not worse than 1.6. It is required by the Passivhaus standard for triple glazed windows to have no more than 0.8 UV value. It is claimed by some suppliers that they have achieved 0.5.
For walls, currently, the U value demanded is under 0.3. Therefore, windows are still a weak spot in a building envelope’s overall thermal efficiency. That is why there is a tremendous amount of pressure for their performance to be improved further.
Glazing Manufacturing Improvements
The introduction of the following has brought on improvements:
- Cold bridges being designed, like aluminium spacers that surround glazed units
- Filling the cavity with an inert gas, normally argon
- Low-emissivity coatings added to the glass to prevent heat from escaping
- Wider cavities in between the two panes of glass, with the optimum distance being 16mm