Environmental profile of Spanish porcelain stoneware tiles

Abstract

Purpose Porcelain stoneware tile (PST) iscurrently the ceram- ic tile of greatest commercial and innovation interest. An envi- ronmental life cycle assessment of different varieties of PST was undertaken to enable hotspots to be identified, strategies tobedefined,differencesbetweenPSTvarietiestobeevaluated andguidanceforPSTmanufacturerstobeprovidedinchoosing the Environmental Product Declaration (EPD) programme that best suited their needs according to grouping criteria. Methods Analysis of previous information allowed three main parameters (thickness, glaze content and mechanical treatment) to be identified in order to encompass all PST var- iations. Fifteen varieties of PST were thus studied. The cover- age of 1 m 2 of household floor surface with the different PST varieties for 50 years was defined as functional unit. The study sets out environmental data whose traceability was verified by independent third parties for obtaining 14 EPDs of PST under Spanish EPD programmes. Results and discussion The study presents PST inventory anal- ysis and environmental impact over the entire life cycle of the studied PST varieties. The natural gas consumed in the manufacturing stage accounted for more than 70% abiotic deple- tion – fossil fuels and global warming; electricity consumption accounted for more than 60% ozo ne layer depletion, while the electricity generated by the cogeneration systems avoided signif- icant environmental impacts in the Spanish power grid mix. The variationsinPSTthickness,amountofglazeandmechanicaltreat- ments were evaluated. The PST variety with the lowest environ- mentalimpactwastheonewiththelowestthickness,wasunglazed and had no mechanical treatments. Similarly, the PST variety with the highest environmental impact was the one with the greatest thickness, was glazed and had been mechanically treated. Conclusions The PST life cycle stage with the highest envi- ronmental impact was the manufacturing stage. The main hotspots found were production and consumption of energy and raw materials extraction. Variation in thickness was a key factor that proportionally influenced almost all studied impact categories; the quantity of glaze strongly modified abiotic de- pletion – elements and eutrophication, while the mechanical treatments contributed mainly to ozone depletion. The study of all PST varieties led to the important conclusion, against the current trend, that differences among them were found to be so significant that declaring a number of PSTs within the same EPD is not directly possible, and it needs preliminary verifi- cation to ensure compliance with the product category rule.