What leads to variations in the results of life-cycle energy assessment? An evidence-based framework for residential buildings

Residential buildings are one of the major contributors to climate change due to their significant impacts on global energy consumption. Hence, most countries have introduced regulations to minimize energy use in residential buildings. To date, the focus of these regulations has mainly been on operational energy while excluding embodied energy. In recent years, extensive studies have highlighted the necessity of minimizing both embodied energy and operational energy by applying the life-cycle energy assessment (LCEA) approach. However, the absence of a standardized framework and calculation methodology for the analysis of embodied energy has reportedly led to variations in the LCEA results. Retrospective research endeavoured to explore the causes of variations, with a limited focus on calculating embodied impacts. Despite the undertaken attempts, there is still a need to investigate the key parameters causing variations in LCEA results by examining methodological approaches of the current studies toward quantifications of embodied and operational energies. This paper aims to address three primary questions: ‘what is the current trend of methodological approach for applying LCEA in residential buildings?’; ‘what are the key parameters causing variations in LCEA results?’; and ‘how can the continued variations in the application of LCEA in residential buildings be overcome?’. To this end, 40 LCEA studies representing 157 cases of residential buildings across 16 countries have been critically reviewed. The findings reveal four principal categories of parameters that potentially contribute to the varying results of LCEAs: system boundary definition, calculation methods, geographical context, and interpretation of results. This paper also proposes a conceptual framework to minimize variations in LCEA studies by standardizing the process of conducting LCEAs.