The simple urban radiation model for estimating mean radiant temperature in idealised street canyons

Thermal comfort is an important component of health-related urban well-being (UrbWellth) of the urban population. Outdoors in sunny conditions the human thermal environment is strongly influenced by radiation fluxes, which are often expressed as a mean radiant temperature (Tmrt). In an urban environment Tmrt is, especially in sunny conditions, strongly influenced by the building morphology due to shading and reflection of radiation. To model these morphological effects within an urban system model for UrbWellth, a simple model for Tmrt is required that simplifies the actual urban environment to reduce computational costs but still considers the most important aspects of Tmrt variability within a city. To do so, within this paper the open-source and modular Simple Urban Radiation Model (SURM) is presented. SURM is validated with respect to different calculation methods of both view factors and radiative fluxes as well as to radiation modification by buildings. The results indicate that SURM models radiative fluxes and radiative influences of buildings sufficiently accurate to be applicable as one component of an urban system model for sunny conditions.