Classification of the influence of urban canyon geometry and reflectance on seasonal solar irradiation in three European cities

Abstract The study presents a methodological framework for simulating, analyzing and classifying the seasonal solar exposure and irradiation uniformity of symmetrical urban canyons in three European cities with different latitudes: Athens, Paris and Helsinki. Parametric solar radiation simulations are conducted by varying the urban canyon geometry, orientation and surface reflectance. The study proposes the Solar Irradiation Ratio (SIR) and develops a qualitative classification scheme for solar exposure and irradiation uniformity in order to compare simulation results from different cities and label each urban canyon surface accordingly. Finally, the study trains and tests Random Forest classifiers which enable the quick classification of any symmetrical canyon geometry by providing canyon geometry, orientation and surface reflectance as inputs. Testing reveals that the classifiers have decent performance (accuracy: 0.89 – 0.94, precision: 0.82 – 0.92) and consequently may be used in early urban design and planning studies to get a quick estimate of the solar performance of a given symmetrical urban canyon, before full-scale simulations take place.