A comparative LCA as a tool for evaluating existing best available techniques (BATs) in facing brick manufacturing and more eco-sustainable coating solutions

Purpose: Ceramic facing bricks are construction materials used to produce an attractive aspect to building walls and provide protection from external exposure. The purpose of this research is twofold: first, to conduct a comparative cradle-to-gate life cycle assessment (LCA) to evaluate environmental impacts of manufacturing options available for obtaining different colours and appearance of facing bricks, and second, basing on LCA results, to examine recent literature and environmental product declaration (EPD) items (ISO 14025:2006) to verify if current EU best available techniques (BATs) in ceramic manufacturing industry that are dated 2007 are still relevant today, especially in the light of current technological progresses. The considered manufacturing options are necessary to obtain three different final appearances of the facing brick. In the first option, the brick is left in its natural colour. The second and third options include the applications of two type of coatings, which are the engobing and the glazing solutions. Methods: The analysis of life cycle stages was performed according to the cradle-to-gate approach (ISO 14040:2006b UNI EN ISO 14040:2006—environmental management-life cycle assessment-principlesand framework;ISO 14044:(2006c) ISO 14044:2006/Amd 1:2017 environmentalmanagement-life cycle assessment-requirements and guidelines-amendment 1/Amd 1:2017). The software tool used is SimaPro® version 9.0.0.31, and inventories are based on ecoinvent v.3.5. LCA was performed basing on ceramic BATs and literature data, assuming the German energy mix. The consistency of results and the evaluation of ceramic BATs were discussed on the basis of a comparison of results with recent LCA studies and application of sensitivity analysis. Results and discussion: One of the results of this study is that coating options entail significant environmental impacts. As instance, the application of both engobe and glaze coatings increases the global warming potential (GWP) up to 7.2% and human toxicity (HT) up to 143.1%. Finally, results confirm the importance of implementing existing saving technologies for the firing stage, being the main contributor to climate change among production activities. Moreover, environmental impacts that have been obtained assessing the product life cycle with BATs are generally higher if compared with current literature, in a range up to + 240%. Conclusions: In conformity with ISO standards, this LCA analyses the potential environmental impacts of facing bricks, considering three manufacturing options. The evidences provided by this study demonstrate the importance to include coating materials in LCA studies involving facing bricks. Finally, results let the authors to conclude that a revision of BATs is necessary in order to update technology requirements that are contained in the document to the current state of the art.