This Math Error Isn't "Cool"

I'm all about "handy" things.  This poor man's air conditioner is pretty nifty:

What can you do with old plastic bottles? Not much you’d think, apart from recycle them. Except, you could make a zero electricity air conditioning unit.

Easy to make, fun--but how well does it work?

The Eco-Cooler reduces temperatures by up to 41ºF (or 5°C), which is pretty impressive given it costs next to nothing to make.

Doh!

41 degrees F is 5 degrees C, yes, but the scales have different starting points. The Celsius scale marks freezing water at 0 degrees, while the Fahrenheit scale has water freezing at 32 degrees.  Thus, an increase or decrease of 41 degrees Fahrenheit has to account for that 32 degree "start"; therefore, a 5 degree C decrease is 9 degrees F.  Not bad, but not 41 degrees.

If that's too esoteric for you, there's always the conversion formula:

F=(9/5)C +32

From the formula you can see that a 5 degree change in Celsius will give a 9 degree change in Fahrenheit.

With temperatures in the Sacramento area projected to be in the 100's this weekend, I wish a few discarded water bottles could drop air temps 41 degrees.