But it also indicates the gap between the panes is no longer sealed ... replace the window. And double-glazed windows aren’t ...

The U-value for a timber double-glazed window will depend on a number of factors - frame design, ventilation, type of gas within sealed units, as well as the number of panes of glass - but for the ...

The double glazing expert added: "PIV units have several great benefits for your home, including improving the quality of air, eliminating humidity and condensation and reducing pollutants.