I have a friend who lives in a big old drafty Victorian house with big windows, in Chicago. She is wondering if getting big heavy drapes would be an energy-saver. Certainly when I've opened drapes in a house like that, it FEELS like you release a big pocket of cold air into the room. But are the drapes really keeping a lot of cold air out of the room? Has this ever been measured? R 1 or R10? Thanks.