Thermal behavior evaluation of ventilated roof under variable solar radiation

A ventilated roof has a good configuration for energy purposes, in order to respect the European Directive priority for building performance requirement to reduce energy consumption. In Mediterranean regions, with high level of solar radiation, the roof design should respect comfort and energy saving, considering that climatic conditions change depending on seasons and territories. This paper illustrates a numerical investigation on a prototypal ventilated roof for residential use, in order to evaluate its thermofluidodynamic behaviors as a function of the solar radiation applied on the top wall of the roof simulating summer and winter conditions. The roof is modeled as a single side and it is analyzed as two-dimensional, in air flow, thanks to the commercial code Ansys-Fluent. Results are given in terms of temperature and pressure distributions, air velocity and temperature profiles along longitudinal and cross sections of the ventilated layer, in order to estimate the differences between the various conditions. Ventilated roof configuration results significant to reach optimal thermal and hygrometric conditions in summer and winter conditions.