Double vs triple glazing: is triple worth it?
Triple glazing is often sold as a straight upgrade. In practice it's a trade-off, and whether it makes sense depends on your property more than on the product.
What changes with a third pane
A third pane and a second cavity generally improve heat retention and can reduce noise, particularly at certain frequencies. The unit is heavier, which puts more demand on frames and hinges, and the whole window costs more.
Where it tends to make sense
Exposed properties, north-facing elevations, rooms you struggle to heat, well-insulated homes where the windows are now the weak point, and homes near persistent noise.
Where double glazing is usually enough
Sheltered mid-terraces, homes where the existing insulation is the real limiting factor, and any project where the extra spend would be better used on more windows or a better frame.
The question to ask
Ask each company for the U-value of both options, quoted on the same window. If they can't tell you, that's your answer about the quote.
What are you looking to replace?
Choose everything that applies.