A scale model for the Urban Canyon Effect quantification: preliminary data analysis

The Urban Canyon Effect (UCE) is responsible of increasing discomfort levels in densely populated areas, characterized by a building layout that produces a noticeable change of the local climate conditions if compared to those of the neighbouring country. A quantitative analysis of the UCE represents a key factor for effective strategies of discomfort mitigation and for design of new districts. An energy-balance analytic model was set up to estimate air, wall and ground temperatures inside the Urban Canyon (UC) as a function of the incoming solar radiation, the UC geometry, the surface properties, and the convection heat-exchange. The fully determined system can be used to predict the UCE for different aspect ratio of the UC (i.e. height/distance ratio, H/D), different convection scenarios (i.e. both natural and forced convection) and different optical properties of the building walls and the ground (i.e. reflectivity and emissivity). The model was applied to data from the monitoring of a scale model resembling the UC. An installation of two identical sets of UC with different H/D ratios (i.e. 0.5, 1.0, and 2.0) was set up and instrumented with temperature sensors, a radiometer and a wind speed and direction sensor. The optical properties of the two sets can be easily changed to simulate different scenarios. Preliminary data from the 2013 summer campaign are presented. The first installation was set up to resemble opaque concrete-like surfaces (i.e. low reflectivity); the second one was covered with a high-reflective coating. Measured data were used to validate the analytic model. The comparison of the measured and/or simulated data may be used to quantify the effect of the surface optic property on the UCE.