Don't remember where I stumbled upon these. But Naturgress is an Italian collection of glazed porcelain tiles, that are certified in Europe for use in Bio-Building (green architecture). The certification comes from the ANAB-IBO-IBN an amalgam of three ecological building associations from Italy, Austria and Germany respectively. They awarded the certificate "based on the environmental impact of the manufacturing cycles, the durability of the material and the energy consumption required during the whole life cycle (transportation, laying, care and maintenance) and for the removal and disposal of the product." In this instance it was probably because the tiles are guaranteed for 50 years against wear and tear, so they no doubt scored high points for longevity, compared to the energy required to produce them. ::Naturgress.