An air-conditioning hat



^ the hat as view from the left side


^ the hat from the right side


^ the hat from the right, but turned on and active

Skills used:


Physics (thermodynamics), Electrical Engineering.




For those of you who do not know, winters in Blacksburg are bad, but summers in Blacksburg are brutal. There was a saying used in the Boy Scouts, that “if your head was warm, you were warm, and if your head was cold you were cold,” and so, to counteract the high heat, I decided to build a hat that would act as air-conditioning.

Since the school recently built a new building to house engineering professors’ offices, they were all moving out of Randolph Hall and McBryde Hall. One of these teachers had the brilliant idea to start a “moving out sale: free stuff to a good home” pile in the lobby. Being an engineer, and after dismantling several ancient scanners if only to steal the belts and optics, I managed to pull an old hat and a stupid little USB powered “refrigerator” for only one can of soda out of the pile, and got to work.

After turning the hat into a visor (no need for that extra material), I ran to RadioShack to get a battery pack, solar panel, and a good switch, and affixed these to the hat. I then removed a square section of the front of the hat and affixed a steel plate to the inside, and attached that to the heat sink and cooling fan I pulled from the USB refrigerator. After some vigorous soldering, I threw on some duct tape for good measure and did a test run.

We know from thermodynamics that heat from a warm object will always travel to a cold object, and that is the process used in this device. The heat from the head will travel into the metal plate and then to the heat sink, where the fan will increase air flow and help disperse it into the air. To humans, the act of losing heat to the heat sink gives the sensation of cold, which is what I was looking for.

After doing a test run, I was not horribly impressed by how well it worked, but it did indeed work. The batteries lasted an acceptable amount of time (about 4-5 hours), and the metal plate was always cool to the touch. Since I tried it on a rather warm night, I am not sure how well the solar panel works, but I anticipate that it will only work as backup to the batteries as opposed to running on its own, and I may cannibalize it for another project later on.

I met someone new during the test run, and her first words to me were, “you’re an engineer aren’t you?”




    • It does work pretty well.
    • It is such a cool style (no pun intended).
    • The indicator light acts as a headlamp if its dark enough.


    • I never liked the feeling of hats
    • This seems like the kind of thing that would just chew through batteries.
    • The batteries supply 4.5 volts, while the fan requires 5 volts. As a result, I am not getting the highest possible efficiency because no one sells 5 volt batteries.


Opportunities for improvement:


Aside from finding a way to make 5 volts, I could find some smaller heat sinks and put those in parallel around the hat so the heat dispersion is not only on a 2 inch square in the middle of the forehead.



It’s totally my style, and I will probably wear it around, but due to its need to always be on, the price of batteries will make it more of a novelty than a practical device.

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