Urbanization impacts Earth’s systems by increasing CO2 emissions, creating urban heat islands (UHI), and affecting climate, energy use, and public health. Understanding urban microclimates and energy and CO2 balances is crucial for designing effective climate change adaptation and mitigation strategies. This paper presents preliminary results from the UrbaNature project, focusing on vegetation’s role in urban microclimates. The goal is to develop a 3D microscale ecophysiological model for CO2, water, and energy exchanges between plants and the urban atmosphere, including a 3D radiation exchange model for urban canyons with tree canopies. Using high-resolution digital surface models (DSMs), land cover, and leaf area index (LAI), we construct a 3D urban landscape of isometric voxels categorized as buildings, trees, terrain, or empty. This landscape supports radiation exchange simulations via a ray tracing algorithm, computing parameters like sky view factor (SVF), and light transmission coefficient, stored in look-up tables (LUTs). Meteorological data from an urban tower in Basel, Switzerland, is used to evaluate the model’s accuracy by comparing simulation results with ground-level station data. Preliminary results show that the model effectively replicates observed shortwave radiation patterns, highlighting its potential to enhance urban climate research and understanding of urban energy balance.