When it comes to window energy efficiency, the pressure is on for homeowners to enhance performance, to the extent that double glazing windows are almost no longer enough.
But can the extra expense of a third pane of glazing really be justified?
The standard for energy performance comparisons is the U-value measurement, also used for roofs, floors and walls. Modern Building Regulations stress that all newly installed windows should have a U-value of no lower than 1.6.
But if you thought that was low, consider that the U value required for walls is 0.3, and you can see that windows generally have the potential to be a thermal efficiency weak spot.
In truth, expert opinion is split on triple glazing. Cold countries such as Sweden and Norway use it widely, and the key benefits are to do with comfort.
You may insulate the roof, floor and walls of a house, but if you ignore the glazing, the result could well be cold spots around the window at night causing draughts and for heat to be drawn away from anyone sitting next to them, leading to issues with condensation.
So glazing must have the same standard of insulation as is found across the property for consistent performance.
When the mercury drops, triple glazing can undoubtedly raise comfort levels. Next to a single-glazed window, for example, the surface temperature is about 1⁰C, next to a triple-glazed one with a centre-pane U value of 0.65, it rises to 18⁰C.
So you should find that a triple glazed window retains the heat in your home better, in a way that could make all the difference to your overall comfort – and your heating bills.
However, window frames also need to be insulated, while, equally, installation must be done carefully and in the right place within the wall assembly.
Just to make things more complicated, triple glazing can (albeit slightly) lessen a window’s heat absorption characteristics. To take this into account, the British Fenestration Rating Council’s energy labelling scheme gives the highest rating to products considered to absorb as much heat as they lose, triple or double glazed.
So it’s true there are possible drawbacks to triple glazing, not least in a climate like ours. Being more expensive to produce, and the greater heaviness of the sections, are among the potential snags.
The problem with that is that just adding more panes of glass not only makes the end product much heavier, but light is prevented from coming through the panes, and there could also be a reduction in how much sunlight the window can absorb.
So future industry developments are likely to focus on new coatings or the sorts of materials which absorb heat in sunlight before releasing it at night.
At Worthing Windows, with some two and a half decades’ experience under our belts, we’re ideally placed to advise you on the energy and thermal performance of your windows, from Ferring to Sompting as well as, of course, Worthing itself. Get in touch with the team today.