Hats. Most runners wear them at least some of the time. My preferred hat has been a desert camo boonie hat, which has performed admirably. Could there be a better solution, though?
My recent discovery and subsequent discussions on moisture-wicking materials and thermoregulation piqued my interest in hats. Specifically, a discussion on Barefoot Ted’s Google Group led me to try a stray sun hat. That same discussion also led me to consider modifications that would make the sun hat even more effective… so I built this:
The thermal chimney hat! It uses a few principles to facilitate cooling.
First, the brim is painted gloss white to reflect the solar energy from the sun. This would be slightly better than the natural tan color of the wicker.
Second, the underside is painted flat black. This will facilitate radiant heat dissipation from the head. Heat absorbed by the underside of the brim will be collected in the rim, conducted to the cooler top (painted white), and dissipated by passing wind via convection. The brim becomes a gaint cooling fin in addition to providing shade for the rest of the head and shoulders. The heat absorbed by the crown (part that fits over your head) will be used to increase the thermal updraft, which helps the next action.
Third, I had to solve the problem of air flow in the crown. The straw hat had small ventilation holes, but they didn’t work well if there wasn’t a breeze (or running fast). The solution was to create a solar chimney of sorts. I got the idea from the Google Group’s discussion on desert-dwellers that wore black robes in extreme heat. The black would heat up. Since hot air rises, cooler air would be sucked in the bottom of the robe, pass the body, and exit the top. This airflow cools the body via convection, which also helps evaporate sweat.It’s the same principle used to cool buildings in hot weather without the use of air conditioning.
By painting the outside of the crown black, it would heat up when exposed to the sun. The inside would also heat up from the radiant heat of the head. This heated air would escape the upper vents cut into the back of the crown, which would also suck cooler air into the lower vent at the front of the crown. The dry incoming air would help evaporate sweat off the top of the head, which would keep it cool. This airflow will continue even if there is no breeze since the airflow is partly assisted by rising heat.
So… will the hat work? We’ll see. I’ll be testing it in a variety of conditions this week. I’ll buy a second unmodified hat to use as a baseline. Stay tuned!
What do you think? Will the principles work? Is this going overboard? Do I have too much free time on my hands? 🙂
On a related note- in anyone is interested, I’ll make you a hat for a small fee. 😉