The humble window shutter is — in many parts of the world — the unsung hero of climate control. What makes them so effective is that they sit outside of the building envelope and, therefore, block sun and thermal heat gain before they get inside. This is an important detail because, once inside, you now have to work that much harder to bring interior temperatures down.

France's contribution to the world of window shutters is one called la jalousie, which was deliberately named after the French word for jealousy. The key design feature is that they allow you to be a voyeur. The louvers, which are traditionally adjustable, allow you to see out, but for the most part block people from seeing in. Hence the name. Supposedly they first took hold in Marseille and then spread to the rest of France. That makes sense.

It's easy to not care about shutters in a world of modern air conditioning, but this is what generations upon generations have been using to regulate the temperatures of their homes. It's dead simple, and it works.