As twenty-first-century life becomes increasingly hectic, technologists continue to search for ways to reduce our burdens. "Useful" time-saving devices have included bagless vacuum cleaners, saucepans that indicate when they are hot, and cars that sound a warning when their driver is going the wrong way.
Self-cleaning windows might seem to be yet another nifty, but fairly pointless, addition to this ever- growing canon of inane novelty. The innovative technology behind them is clever and effective, but how worried are people about the cleanliness of their windows? It turns out that they are quite concerned about it. PPG Industries, which pioneered the first self- cleaning windows in 2001, carried out consumer research through a survey in Better Homes & Gardens magazine in 2000, and self-cleaning windows came out at the top in a list of fantasy products.
The windows (named Sun Clean by PPG) are self- cleaning because an extremely thin layer of titanium oxide on the glass reacts with ultraviolet (UV) light from sunlight to break down organic dirt on the window. The coating has hydrophilic properties, so rainwater does not bead on these windows in the way that it does on normal glass. Instead, the water forms a film over the whole pane, which helps to wash the dirt from the glass and keep it clean.
The popularity of this advance has yet to be proven because the public has not exactly rushed out to replace their existing window panes with self-cleaning ones. Sales of the product have been slower than expected. Self-cleaning windows are now available from numerous glass manufacturers, but the sluggish sales suggest that, for the average home owner, the 15 to 20 percent extra cost might not be worth it.
