Running an air conditioning unit is bad for the environment, and bad for your wallet. With the heatwave planning a return visit, we found a way to make our own cooling system!   You will need:

  • A plastic box
  • A fan
  • A fan grill
  • Empty milk bottles
  • Salt
  • Water

Here’s what you need to do:

Heavily salt the water and fill your empty milk bottles up. Stick them in the freezer. How many you’ll need depends on the size of the box you’re using. Putting salt in the mix means the water will stay frozen for longer, but the system will work with anything frozen; your unwanted frozen veg, or even lots and lots of ice cubes. Remember though, the smaller the frozen thing, the quicker it’ll melt and the sooner you’ll have to replace it.

Cut a hole in one side big enough for the face of your fan, and cut another hole on the opposite side big enough for your fan grill. You can use a big grill, several little grills… whatever you’ve got that fits. If you cut the hole to the right size, the fan and grill should just slot in and sit happily, but you could also glue them if you wanted to.

Once your milk bottles have frozen, plonk them in the box, plug in your fan and enjoy the ice-cold air!

We made a rather large one, but why not try making a desktop version using a USB fan, an ice-cream tub and ice-cubes?  

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