Stochastic hybrid embodied CO₂-eq analysis: An application to the Irish apartment building sector

Although embodied CO₂-eq analysis has seen recent developments as evident in the establishment of the ISO 14040 and 14044 LCA standards, it is recognized that due to weaknesses in gathering data on product-related emissions, embodied CO₂-eq values are probabilistic. This paper presents a stochastic analysis of hybrid embodied CO₂-eq in buildings to account for this weakness in traditional methods and, by way of example, applies it to an Irish construction-sector case study. Using seven apartment buildings, 70,000 results are simulated with Monte Carlo analysis and used to derive probabilistic and cumulative embodied CO₂-eq intensity distributions for apartment buildings in Ireland. A Wakeby distribution with known statistical parameters and uncertainty was derived for the average embodied CO₂-eq intensity of apartment building in Ireland. The mean hybrid embodied CO₂-eq (ECO₂-eq) intensity was estimated to be 1636 gCO₂-eq/ with an uncertainty of 73 gCO₂-eq/. The stochastic analysis helps to account for variability in input variables into embodied CO₂-eq analysis. The application of the stochastic embodied CO₂-eq analysis as demonstrated in this study can be extended to other building sectors and countries and can form the basis for the development of evidence-based policy formulation since it provides greater information on embodied CO₂-eq intensities of buildings than deterministic approaches.