Our house was built in 1740, and has a kitchen added on to the back of the house. All this winter, the kitchen had been the coldest place in the house. This didn't make much sense to me, as the rest of the house has old wooden windows and no insulation, while this addition was made in the 70's and is insulated and has vinyl double pane windows. They are the type with the crank to open them. I had just chalked it up to the fact that there is an entrance door in this addition, as well as a pretty large wall cutout for the washer/dryer that goes down to the basement. Oh boy was I wrong. The last time we had the windows open was in the summer/fall. I was cleaning some toys off of the window sill for the large bay window, where I noticed that one of the windows was OPEN about 1/4 inch. The crank failed to close the window all the way, and the latches were engaged, but didn't actually catch onto the female side of the latches on the window itself. This was likely open the entire winter season. Needless to say, I was quite pi$$ed at myself for not having noticed this when I was going around with the caulk gun at the beginning of the season and sealing up drafts.