I know that in Canada, what they used to do for measuring windchill factor was just hang a 10 gallon water bottle, and measure how much faster it froze at different windspeeds.

I believe they have now updated their system, and they had volunteers from the army stand in a windtunnel, and they measured how fast the body cooled off at different windspeeds.

I'm not so sure the calculation will be so simple. Plus, you also have to keep in mind surface area calculations, which could become complicated.