  We study the localization volumes $V$ (participation ratio) of electronic
wave functions in the 2d-Anderson model with diagonal disorder. Using a
renormalization procedure, we show that at the band edges, i.e. for energies
$E\approx \pm 4$, $V$ is inversely proportional to the variance $\var$ of the
site potentials. Using scaling arguments, we show that in the neighborhood of
$E=\pm 4$, $V$ scales as $V=\var^{-1}g((4-\ve E\ve)/\var)$ with the scaling
function $g(x)$. Numerical simulations confirm this scaling ansatz.
