For optimal thermal insulation of windows to maximize heat retention in winter and coolness in summer, secondary glazing is highly effective. This method, as outlined on Windows thermal insulation
https://scottjameswindows.co.uk/secondary-glazing-essex/ , involves adding a secondary layer of glass to existing windows, creating an insulating air gap that significantly enhances thermal performance. Additionally, incorporating low-emissivity (low-E) glass can further improve insulation, as it features a thin coating that reflects interior temperatures back inside, helping to keep spaces warmer in winter and cooler in summer. Together, these materials not only improve comfort but also contribute to substantial energy savings by minimizing heat transfer.