Sometimes it feels like science is just like, “Oh, you always wondered about that, eh? BOOM, here’s the answer.” Thank goodness researchers felt like investigating the all-important question of whether or not those foam can/bottle koozies (maybe you call them “cozies”) keep beer and other beverages cold, because otherwise we’d be left wondering forever and ever.
The stalwart scientific minds at the University of Washington in Seattle produced a study that concludes that yes, koozies do in fact keep things cold. Go on, wipe your brow in relief.
According to the study published in Physics Today (by way of Lifehacker), the researchers looked into how quickly the cold bevvies went from cool to warm depending on the climate around them. Humidity is more of an issue than hot temperatures, it turns out, as the condensation on a can when it’s humid will release latent heat.
At 35 °C and a relative humidity greater than 60%, the temperature rise due to latent heating exceeds that due to heat transfer from dry air: Latent heating is the dominant factor warming your cold beer. The rate of latent heating decreases as the outside of the can warms, and the heating ceases completely once the can’s surface temperature exceeds the dew point (the temperature to which air with a given water-vapor content must be cooled to become saturated) and water no longer condenses on it.
As for that koozy, the study’s author notes this very important nugget: “Probably the most important thing a beer koozy does is not simply insulate the can, but keep condensation from forming on the outside of it.”
[Cue college students adding a koozy to that can of shower beer, which, if you don't know, just means a beer you drink in the shower because there is no way you can waste one minute of pre-gaming before The Big Party]
Now if someone could just do a study on how to cut down on the amount of branded koozies I have stuffed into a kitchen drawer, that would be helpful.
Condensation, atmospheric motion, and cold beer [Physics Today]