Photocatalytic self-cleaning coatings for building facade maintenance. Performance analysis through a case-study application

Facade maintenance has become a key aspect in building management, due the specific actions involved and operation related costs. Within this framework, the application of titanium dioxide photocatalytic sol-gel products on facade elements offers a wide range of opportunities to ensure proper functionality maintenance over time. This paper illustrates the self-cleaning performance of titanium dioxide and silicon dioxide based coatings applied to different kinds of cladding materials. All tested samples were opaque. Preliminary laboratory tests were performed by means of water contact angle measurements to verify hydrophobic and hydrophilic behaviour prior to outdoor application. Afterwards, outdoor tests were performed to monitor colour variation over a 36-month period to verify product effectiveness and durability. Results proved that the application of functionalized nanotechnological coating to a facade can significantly facilitate cleaning operations and reduce the necessary frequency over time. In addition, the output provides some preliminary information about the exposure condition influence on self-cleaning performance, which could be further investigated in the future.