Comparative evaluations of sustainability, durability and resilience of external envelopes for environmentally efficient buildings

The building sector is affected by a significant confusion between the concepts of sustainability and energetic efficiency: indeed, both the paradigms have the aim of safeguarding the planet, but the strategies to enact them certainly follow two different paths, often in contrast between them. The design of building envelopes has definite performance requirements, according to the current framework, but in any case the technological choices to fulfil them are not univocally determined. As an example, the objective of obtaining building envelopes with low transmittance can be reached by a huge number of typologies of solutions and materials, but of course the possible evaluations in terms of sustainability may in some cases show results that overturn the energetic assessment. Also, considering the strict relation that exists between durability (also in terms of resilience) and sustainability, it can be concluded that the most correct tendency for materials and products can be – more in general – defined as environmental efficiency, the so-called eco-compatibility. Taking moves from the scientific literature on products and materials, both from the point of view of sustainability, and from that of durability and resilience, this work proposes a number of comparative evaluations that analyse the main systems and components of the external envelopes: built-up roofs and roof systems, opaque and transparent walls, ground floor slabs, doors and windows. LCA analyses, durability assessments and considerations on resilience carried out on the abovementioned systems and components provide very interesting results to guide designers towards more conscious choices, aimed to integrate the different (and sometimes contradictory) aspects that allow to realize energetically and environmentally efficient buildings