Effect of LCA Data Sources on GBRS Reference Values: The Envelope of an Italian Passive House

Scientific literature provides evidence that mitigating the effects of a building’s operation does not in itself ensure an overall improvement in its environmental performance. A Life Cycle Assessment (LCA) plays a key role in gauging the overall environmental performance of a building although several authors argue that the lack of LCA threshold values makes it difficult to compare design options or measure whether reduced impact targets are achieved. This has led the Green Building Rating Systems (GBRS) to include the LCA within their evaluation criteria and, in like Active House (AH), establish threshold values of the main impact categories to quantify the level of performance achieved. Since the reliability of the data sources is a crucial issue for applying the LCA method, the effectiveness of their implementation within the GBRS also strictly depends on the origin of the impact values. To quantify the extent to which the source affects the impacts calculated by the LCA threshold value in AH, the present study compared the outcomes of two assessments carried out in parallel using two different data sources: AH–LCA evaluation tool v.1.6 and the Environmental Product Declaration (EPD). A Passive House (PH)-compliant, small residential building was selected as a case study, as this is a standard that excels in ultra-low-energy performance. Moreover, given the crucial role that the envelope plays in the PH standard, the analysis was undertaken on the envelope of a PH-compliant building located in Northern Italy. To stress the influence of embedded effects in a Passive House, the assessment focused on the production and end-of-life stages of building materials. The comparison showed a relevant difference between the two scenarios for all the environmental indicators: e.g., deviations of 10% for Global Warming Potential, 20% for Acidification Potential and Eutrophication Potential, and 40–50% for Renewable Primary Energy