Allow Grade II listed properties should be allowed to have slim double glazing. There are around 350,0000 grade II listed properties in England. Double glazing allows buildings to be much more energy efficient, and are one of the most cost effective energy saving inverstments and homeowner can make. Conservation officers in local authorities are completely against allowing double glazing in Grade II listed properties. I would completely agree with them 15 years ago when double glazing was air filled wide with large visabel seals around the glazing. Glazing manufacturers now have denser gases allowing building regulation comlpient windows to be much slimer and the methods of construction mean the main glazing seal is hidden within the frame. There will however be some instances where adding double glazied wood or metal windows will not be allowed as fitting heavier windows would destroy the "fabric of he building", but in most cases this would be an easy change to make. All this change requires is the goverment telling council conservation officers that slim well designed double glazing (not-uPVC) is allowed.
Double glazing is one of the most cost effective energy saving methods a homeowner can invest in.