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

Abstract

The development of embodied CO2-eq analysis has progressed significantly in recent years and has become a mainstream practice in many industries as evidenced by the development of the ISO 14040 and 14044 life cycle assessment (LCA) standards. However, it is recognized that due to weaknesses in gathering data on product-related emissions, embodied CO2-eq values are probabilistic. This paper therefore 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 buildings in Ireland. The mean hybrid embodied CO2-eq (ECO2-eq) intensity was estimated to be 1,636 gCO2-eq/€ with an uncertainty of 73 gCO2-eq/€. The stochastic analysis helps to account for variability in input variables into LCA and embodied energy and 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 of embodied CO2-eq intensities of building than deterministic approaches.