I was wandering around a local heritage property the other day - not really taking notice of any particular thing, when I noticed how well fitting the shutters were around the very tall windows in the second ballroom. There are five floor to ceiling windows, each about 100mm wide, and each casement has a shutter to close off against the elements. Saving the room from excessive sunlight is the name of the game but when the salon was added on to the house in the late 1800s, this was never a thought, they had no idea about planet warming worries. Just keeping the coldest of weather out! Nowadays we need to check our windows and frames for any perish problems due to extreme heat - it used to be worries about excessive rain and frost. Getting in the experts to look at wooden framed windows and doors is essential - you cannot do this properly as an amateur.