In the European Union, the building sector accounts for more than 40% of the energy consumption and environmental impacts, representing the area with the greatest potential for intervention. In addition to the existing policies that promote the energy efficiency use in building, the embodied energy in the materials and the included processes in the building life cycle should be considered. Insulation materials are an essential part of the energy savings during the use of the building, but also of the embodied energy in the building construction. Most environmental studies about insulation materials at date had focused on the environmental impacts of the production of materials. This article aims to broaden the scope and provides a detailed environmental assessment of various thermal insulation materials applied in different types of façade systems in each Spanish climate zones by means of LCA from cradle to site approach methodology. The results show that the most impacting alternative is the ventilated façade in combination with the most impacting insulation materials: mineral wool and expanded polystyrene. Meanwhile the most advisable façade in all the climate zones is the external insulation option in combination with any alternative of insulation. The environmental impacts are very different between insulation materials, so it can be noted the relevance of the choice of the insulation. This behaviour is determined by the physical and insulation properties of different materials, but also the environmental performance of them.

Defining sustainable cities is not straightforward. The main issues involved in urban sustainability are buildings, energy, food, green areas and landscape, mobility, urban planning, water and waste; and their improvement is promoted through different strategies. However, a quantitative method, such as life cycle thinking (LCT), is essential to evaluating these strategies. This paper reviews LCT studies related to urban issues to identify the main research gaps in the evaluation of these improvement strategies. The review identifies the main sustainability strategies associated with each urban issue and compiles articles that deal with these strategies through LCT, including environmental life cycle assessment (LCA), life cycle costing (LCC), social LCA (S-LCA) and life cycle sustainability assessment (LCSA), as well as integrated analyses with combined tools. Water, waste and buildings are the urban issues that accounted for a larger amount of studies. In contrast, a limited number of papers assessed urban planning and energy (excluding energy in buildings). Strong interrelations among urban issues were identified, most of them including water. In terms of methods, 79% of the studies exclusively applied life cycle tools (i.e., LCA, LCC, S-LCA or LCSA). Within this group, the environmental dimension was the focus of 84% of the papers. Single environmental indicators (e.g., global warming) were common in 20% of the analyses, highlighting the need to integrate more impact categories to prevent trade-offs. In the field of social and sustainability assessment, there is a need for methodological advances that foster their application in urban areas. Further research should cover the thematic and methodological gaps identified in this paper, such as developing models that assess complex urban issues, generating comprehensive LCT studies and promoting multi-indicators. Life cycle tools might benefit from revising the methodology with stakeholders to optimize the understanding and communication of life cycle results for policy-and decision-making processes.

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