Investigation on the effect of innovative cool tiles on local indoor thermal conditions: Finite element modeling and continuous monitoring

The achievement of building indoor thermal comfort conditions with the minimum energy need represents a challenge for both designers and researchers. To this aim, the development of passive strategies, e.g. cool roofs, for reducing the thermal gain entering building envelopes has spread in the scientific community. In this view, Computational Fluid Dynamic method is applied in this research in order to quantify the effect of a cool roof solution within the indoor environment of the thermal zone adjacent to the roof, by analyzing the attic local conditions. The case study is represented by an attic room of a continuously monitored residential building located in central Italy. A two-dimensional finite element analysis is carried out to investigate the indoor air temperature and air velocity field inside the attic. The available experimental data are used for validation. Therefore, the thermal profiles generated by (i) the roof with traditional brown-colored brick tiles and (ii) the same roof with innovative cool clay tiles are investigated. The final purpose is to compare the indoor thermal comfort conditions generated within the vertical cross section of the attic, in order to study the cool roof effect at different height of occupants' body. The main results show up to 2.79 K and 1.54 K air temperature difference between the cool and traditional roof configurations, in summer and winter conditions, respectively. A thermal stratification is detected during summer inside the attic, leading to strongly non homogeneous comfort conditions, particularly marked in the "hot" tiles scenario, demonstrating the usefulness of this contribution.