Summer days in Spain can easily reach a blistering 104º F in the shade. Locals have adapted a technique for fending off the sweltering heat by using frozen water bottles. In a region where traditional air conditioning can be pricey and not the best for the planet, this method turns out to be both budget-friendly and more sustainable. Start by filling a plastic water bottle about three-quarters full with water. It’s important not to fill it to the top since water expands when it freezes, and you definitely don’t want your bottle to pop. Once filled, pop the bottle in the freezer until the water turns solid. After it’s fully frozen, place the bottle up high in your room, like on a shelf. This works because cold air is heavier than warm air, so it sinks to the floor while the warmer air rises toward the bottle. When that warm air meets the icy surface, it cools down and drops back again, setting up a slow cycle that gradually cools the room. To catch any drips from condensation, put a container underneath the bottle. If you want to double-down on this cooling trick, try pairing it with a fan. As the fan blows air over the ice, it spreads the cool air around the room, kind of like a makeshift air conditioner. Keep in mind, though, that while this works well in small spaces like bedrooms or offices, its effect only lasts until the ice melts completely. It might not be enough for larger living areas.
