The interaction of solar irradiation with mesoporous composites of high water vapor adsorption capacity in comparison to materials used in the external building surfaces was investigated in a wind tunnel of adjustable environmental parameters. Prior to the tunnel experiments, all materials were characterized with different techniques while their thermal and optical properties were also determined. In cyclic experiments inside the tunnel, the maximum temperature in the mesoporous materials was much lower than the corresponding temperature inside typical materials of external building surfaces. Additionally, titanium semiconducting nano-oxides were prepared in situ on the mesoporous structure and were tested for the photodegradation of a model compound under UV irradiation. The results indicate that by supporting the oxides on hydrophilic porous materials, different parts of the solar spectrum could be utilized for simultaneous multifunctional purposes.