A fast model of radiative impact on structures exposed to a fire front in the urban interface is presented. The front is viewed as a collection of turbulent diffusion flames whose properties (composition and temperature) are taken from a database previously created from a three-dimensional computational fluid dynamics model. Using the gray soot assumption, two gas radiative property models, the spectral line-based weighted-sum-of-gray-gases and a simpler gray gas model, are compared in terms of accuracy and computational time. Applied to the curved fire front propagation, the thermal response of structures is estimated as well as fire safety zones. It is found that radiation can lead to pilot ignition under the action of firebrands or flame contact.