Lotusan self-cleaning paint, Sto AG.
I’ve been fascinated by materials that have inherent cleaning properties. Self-cleaning paint and self-cleaning glass, for example, have specially-treated surfaces that employ the natural sheeting action of rainwater to remove dirt. Materials comprised of healthy percentages of titanium dioxide—like TX Active white cement or Reben paint—not only keep themselves clean but also trigger a photocatalytic reaction with sunlight that reduces local airborne pollutants. I call these substances remediating materials for their capacity to improve environmental conditions. Remember all the hoopla about reducing off-gassing and lowering volatile organic compounds (VOCs) in building products? Remediating materials aren’t simply engineered to pollute less; they actually make things better.
The Milan-based company Italcementi claims that if 15% of urban surfaces in a city the size of Milan were covered with their product, airborne pollutants would be reduced by 50%. This should surely give cause for celebration, and we could imagine advocating that effective quantities of TiO2 be included in all appropriate urban surfaces. Yet, we should also think of the potential consequences. By focusing the capability of environmental remediation within construction materials, could we become lazy and simply pollute more? Are these materials simply the next stage in our endless search for convenience? (How about self-cleaning carpet that requires less vacuuming, or self-washing clothes, for example?) Obviously, I am being tongue-in-cheek here—modern convenience certainly has its good points; however, we should be careful when specifying these materials that we remember to clean up the source of the pollution. Perhaps the sale of these products could send a message to local dirty utilities or factories. The purchase of self-cleaning cement, for example, might initiate an automated email to the customer’s nearest elected official, saying “I’m doing my part to clean the air—please help.”