People today are choosing more and more to opt for double glazed sash windows as they combine the traditional beauty and charm of sash windows with energy efficiency desired in a modern home. Double glazed sash windows work by combining two layers of glass which are separated by a sealed air pocket. The first piece of glass in these double-glazed sash windows serves the same purpose as the glass in a normal, single glazed window. However, when you combine this with a second pane of glass, this provides twice the noise barrier. There is an inert gas in the air pocket between the two pieces of glass called argon which is a poor heat conductor, this is because the trapped air has no room to circulate to conduct and transfer heat. Meaning that the warm air from your house is kept in, making them more cost-effective and energy-efficient. Thus, adding value to your property. By adding a second piece of glass to make double glazed sash windows, you are also providing more security to your home. It gives further strength to the window by making it harder to smash, therefore reducing the risk of a break-in.