Building’s Operational vs Embodied Energy: needs and barriers for a more reliable environmental impact balance

To comply with EU directives, which require new buildings to be nZEB by 2021 (2010/31/EC) and all buildings to be nZEB by 2050 (2018/844/EC), the construction industry has mainly focused on the containment of energy consumption during use, but scientific literature highlights that techniques employed to achieve higher operational energy efficiency lead to an increase of embodied energy, embodied carbon and other environmental impacts, especially those related to the manufacturing of building materials. The more stringent energy standards have thus reduced the impacts of the building operational phase, raising those relating to materials and components which are required to allow the buildings achieving these benefits. Several evidences of this trend are provided by applying the Life Cycle Assessment (LCA): although that method is not currently addressed by the EPBD, the key role that the embedded impacts play on the building environmental balance is confirmed. Though a precise calculation of embedded impacts is difficult to perform, due to the many factors involved, the estimation of their share compared to the operating impacts is crucial to determine an effective building energy and environmental balance. Moving toward this target, the Sustainable Building Rating Systems (SBRS) are progressively integrating LCA-based criteria within their protocols. This should provide a simplified and standardized approach thus helping their application in building sector, as preconized by the literature. However, several discrepancies emerge in both method’s application and interpretation of the results among the different SBRSs in use worldwide