Effective hadron models commonly require the computation of functional determinants. In the static case these are one‐loop vacuum polarization energies, known as Casimir energies. In this talk I will present general methods to efficiently compute renormalized one‐loop vacuum polarization energies and energy densities and apply these methods to construct soliton solutions within a variational approach. This calculational method is particularly useful to study singular limits that emerge in the discussion of theclassicalCasimir problem which is usually posed as the response of a fluctuating quantum field to externally imposed boundary conditions. © 2003 American Institute of Physics