Replacement window and door designs enhance and maintain the property's historic character. In terms of repairs and upgrades to the existing windows, only 10% of the total heat loss through the building envelope is attributed to glass, while 15% is lost through draughts and draught-proofing. Draught proofing is straightforward and cost-effective. We also prefer an elegant secondary glazing system that is nearly invisible from within. Combined with traditional heritage glass (wavy/distorted surface character), we have optimised the proposals to improve the existing windows, ensuring they appear authentic while being energy-efficient, sustainable, and meeting modern performance standards. Moreover, utilising the internal Victorian timber shutters and heavy curtains at night offers the same thermal performance as double glazing. The combination of these proposals is highly effective, and the client values the authentic use of the property’s period features