We had out polycarbonate roof replaced about 18 months ago. We had the choice of a solid lightweight roof or a replacement insulated glass roof. The price was similar for each at about £6k for a 5m x 5m conservatory. The supplier reckoned the thermal/insulation qualities of each were similar.
In the end we went with glass and we’re glad we did as it leaves the conservatory a lovely light room where you can now lie on the couch and look at the sky.
HOWEVER….while not quite as cold in the summer or quite as hot in the winter, it has not made it into an all-year completely useable room, but this could be because we only had the roof done and didn’t replace the two glazed sidewalls with better insulated panels, nor do we have curtains or blinds.
The whole roof was done in a day, including glass and new roof frame to fit it on.