Towards Zero-Carbon Buildings: Challenges and Opportunities from Reversing the Material Pyramid

The decarbonization of the built environment, both in new construction and renovation, is crucial to mitigate its relevant impact on climate change and achieve the Paris Agreement goals. This study presents a systematic LCA-based methodology to assess the whole-life carbon emissions of buildings, applied to a proposal for the regeneration of one of Milan, Italy’s, disused railway yards. As an entry for the 2020 Reinventing Cities competition, Scalo Lambrate is a project for a mainly residential neighborhood with a public park. Strategies to reduce carbon emissions deriving both from the operational energy and construction and maintenance were evaluated and their effects compared to a reference scenario over a time horizon of 100 years. The results show that, while the opportunities to reduce carbon emissions during the use phase are somehow limited due to the already stringent performance requirements for new builds, the use of fast-growing biogenic materials for construction materials, even if mixed with more traditional ones, can provide a significant reduction in the global warming potential over the whole life cycle, with a reduction of 70% compared to the baseline. The remaining emissions can be offset with afforestation initiatives, which, however, must be assessed against land use issues.