Radiative heat transfer in its classical context is defined by Planck’s blackbody radiation. However, in the near-field regime, where the distances between mediums becomes comparable or much smaller than the thermal wavelength, Planck’s law of radiation breaks down and radiative heat transfer can be enhanced by orders of magnitude. This enhancement is strongly dependent on the materials, separation distance and surface properties of the mediums. In order to evaluate the mechanism of radiative heat transfer at nanoscale, theoretical, numerical or experimental analysis can be carried out. In this project, we have developed a direct numerical algorithm, Near-field Radiative Transfer Finite Difference Time Domain Method (NF-RT-FDTD) for evaluation of radiative heat transfer at nanoscale. We have investigated geometries of various shape, size, material and surface characteristics and explored the applications of these systems in areas such as energy harvesting and radiative cooling. The project is currently focused on investigation and evaluation of near-field radiative transfer in biologically inspired nanostructures. In particular, the possibility of achieving radiative cooling in buildings by nanostructures inspired by Morpho butterfly structure is investigated.