stopping heat loss from stained glass window

barnaclebill

We have a pretty stained glass half moon shaped window in the lounge, all the other windows in the house a double glazed upvc and I want to insulate the stained glass window to stop heat loss.
I know there is a way with heavy duty cling film but any other ideas, get a piece of clear glass cut and fit it against the wood frame on the inside ?
Any ideas

martinsurrey

secondary glazing