Historic windows with original glass should be retained, overhauled (timber may have distorted over a period of time), cleaned and fitted with concealed draught-proofing, instead of being replaced with modern double glazing. If the historic fabric is beyond repair or has been altered in the past, windows may be replaced subject to LBC.
Original crown glass is characterised by curved and bellied waves often visible in individual panes when viewed in sunlight. As it is no longer produced, historic crown glass should be maintained and preserved.
Well maintained timber windows can be repaired to last hundreds of years and be re-used at the end of their lifetime. Window frames should be made of sustainably sourced timber instead of U-PVC or other materials high in embodied energy. U-PVC frames spoil the building’s authentic character, are not able to be repaired and are difficult to recycle.