For those who don’t want thick double glazing, trim double glazing has width of only all-around 14mm (While some are as slim as 10mm) and is much more economical. The U-Worth (the measurement that suggests the window’s thermal performance) is better and trim glazing is a lot more aesthetically satisfying. https://sethmjvju.wizzardsblog.com/35807650/examine-this-report-on-sash-windows