Wind Resource Assessment Calculator

Average wind speed alone can't distinguish a site with steady, moderate winds from one with long calm spells punctuated by strong gusts — two sites can share the same mean but have very different energy potential. The shape parameter k describes how spread out wind speeds are around that mean, letting the calculator derive a full Weibull distribution and compute power density correctly, since power depends on the cube of wind speed, not the average speed cubed.

The calculator applies the wind shear power law, multiplying your measured speed by (hub height / measurement height) raised to the surface roughness exponent you enter. A lower exponent (around 0.14) reflects open terrain with less friction near the ground, while a higher exponent (around 0.25) reflects suburban or forested sites where obstacles slow wind more near the surface, so the same measured speed extrapolates to a lower hub-height speed at a rougher site.

Scale parameter c is derived from your hub-height mean speed divided by the gamma function evaluated at (1 + 1/k), and it characterizes the Weibull distribution's spread rather than being the mean itself — for the common default of k=2, c ends up somewhat higher than the mean. The calculator approximates the gamma function with Stirling's approximation, so results are very close to a full statistical package but not bit-for-bit identical.

Wind class is looked up directly from the calculated wind power density: Class 1 is the best resource at 800 W/m² or higher, stepping down through Classes 2-4, with Class 5 covering anything below 200 W/m². These bands follow the IEC convention used in commercial wind resource assessment, and generally, Class 3 or higher is considered viable for utility-scale development while lower classes favor smaller turbines or non-viable sites.