A Field Study on the Environmental Conditions of Street Canyons in Dense, Historic, and Urban Centres in the Mediterranean. The Case of Nicosia, Cyprus

Placing urban morphology within the climate context raises insightful comments regarding energy consumption, air quality, and the liveability of cities. The aim of this study is to investigate the thermal and airflow characteristics of street canyons in historic centres with substantial geometrical heterogeneity. An additional aim is to decipher the role of urban compactness—both at street canyon and neighbourhood scales—in determining the possible variation of the ventilation characteristics in the real urban field. For this reason, field measurements of meteorological variables were conducted in three urban canyons situated in two dense, organically developed, neighbourhoods in the historic centre of Nicosia, Cyprus. The urban canyons were selected based on their morphometric characteristics, i.e. orientation, packing densities (λ_p, λ_f), aspect ratio, and sky view factor. The measurements show a clear difference in the regime of wind during the day and the night. In addition, the daily air temperature in the street canyons is greater than that measured at the rooftop level; yet the overall temperature levels do not differ significantly. The median of the normalised canyon velocity to reference wind speed (U_c/U_ref) is 0.342. In conclusion, it is highlighted that airflow in heterogeneous street canyons is much more complex than in simplified homogeneous street canyon geometries.