Improving the energy efficiency of our homes and thereby reducing our carbon footprint, is becoming an important part of everyday life now. Pressure is increasing to improve the performance of windows when it comes to saving energy and many people are asking the question: do we really need triple glazing rather than double glazing?
The U-value system of measurement is used to compare overall window performance and we do this similarly with floors, roofs and walls in the home. The U-value of traditional, single pane windows is over 5. In contrast, double glazing now scores 1.6 at the most. This has improved from a score of more than 3 previously, through improvements and innovations of windows and the demands by Building Regulations that glazing be more efficient than in the past.
Improvements in double glazed windows are due to a number of factors, such as panes of glass featuring wider cavities between them such as 16mm gaps. This cavity can be filled with a gas such as argon. To stop heat escaping, special coatings have been added to the glass itself.
These steps are positive of course, but as the regulation is for walls to have a U-value of less than 0.3, there is still room for improvement in glazing innovations. Windows remain the weak part of a home’s thermal efficiency rating.
Triple glazing is commonly used in countries such as Norway and Sweden where winters are extremely cold. The PassivHause (ultra energy efficient home) standard is for a U-value of 0.8 or less. In order to achieve this standard with a window, the frame has to also be insulated and within the cavity the gas krypton is incorporated, to replace argon. These lead to a more expensive manufacturing process.
However, a house that has had its walls, floor and roof insulated effectively, but not its glazing, will produce uncomfortable cold spots around the windows, causing draughts and allowing heat to escape. Glazing, therefore, has to match the overall insulation of a home in order for the home to be as efficient as possible.
Tests carried out in Germany resulted in findings that showed the internal surface temperature against different forms of glazing varied; from 16 degrees Celsius next to a modern double glazed unit, and 18 degrees Celsius next to a triple glazed window.
With these results, you can see how triple glazing can make a difference, whilst not necessarily with heating bills, but in the overall comfort of the home you live in.
Because triple glazing costs more to produce, many argue that it is simply not necessary in our climate. The government, however, is encouraging the German PassivHaus standard of low energy to be used as a rating, meaning that triple glazing will be necessary to achieve a 0.8 U-value.
As the pressure increases for households to improve energy efficiencies further, triple glazing will become more integrated into British homes, where its value will be felt in terms of overall comfort.