If you live some where that is not temperate year round you may not have run into this abominable style of windows. For obvious reasons, installing these things somewhere cold is a terrible idea but installing them somewhere warm is also silly.
Invented well before the advent of air conditioning, Jalousie windows are meant to utilise natural ventilation to cool homes in hot areas like Southern California. Now that we have entered a more modern age where air conditioners are pretty standard in places like Los Angeles, Jalousie windows are a waste of money, energy , and resources.
Which brings us to the crux of the matter; the importance of good window insulation. Tashman Home Center is one of the few remaining retailers of louvre windows but we do not recommend them at all.