UPVC windows are a popular option, but what makes them energy efficient?
To answer that question, here are the 5 Top energy saving features of UPVC Windows.
The sealed units are comprised of the outer & inner panes of glass, usually each pane is 4mm thick. The separating gap between the panes is the feature that creates most of the insulation for double glazing.
Gap sizes range from 6mm to 20mm. With the thickness of the glass added, that gives total dimensions ranging from 14mm (6+4+4) to 28mm (20+4+4).
A 14mm or 16mm sealed unit (total 22mm or 24mm) is perfectly adequate for most circumstances.
Having a “heavy” gas like Argon inside the gap will reduce heat transfer from one side to the other. Argon gas filled double glazing is quite popular, however, you could use Xenon or Krypton instead.
The drawback with using Xenon or Krypton is that the cost will be higher.
The inner & outer panes have to be held apart to maintain the gap and this is achieved by using spacers around the edge.
Aluminium spacers can often be used here, but as this metal is a good conductor of heat, it’s not really that efficient.
Warm edge spacers are available to reduce this potential inefficiency. They can be manufactured from composite plastics or elastomeric foamed rubber.
Given that some statistics suggest that 80% of energy loss occurs at the edges, fitting “warm” spacers is the sensible thing to do.
There are 2 features in 1 here. The first is that uPVC is a very good insulator itself and does not promote heat or cold transfer.
Secondly, the frame profiles themselves are chambered, much like a honeycomb. You may hear mention of the number of the chambers (typically from 4 to 8). This will have an impact on energy saving because, as a rule of thumb, having more chambers provides for higher energy efficiency.
This energy saving feature is, in effect, an ultra-thin metal oxide coating on the glass itself. The basic idea is that the Low-e coating reflects heat.
Fitted correctly, the window will then reflect your heat back into your home instead of radiating it outwards, thus keeping your home warmer. https://www.pilkington.com/en-gb/uk/householders/types-of-glass/energy-efficient-glass/how-does-it-work
However, having all of these 5 Top energy saving features in your UPVC windows will be pointless if the windows themselves are poorly fitted.
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Do your “due-diligence” – Get at least 4 or 5 written quotations from professional installers, ask for references from previous customers, and then look for the deal that represents the best value for money to you.