Whole life carbon assessment of representative building typologies for nearly zero energy building definitions

Evolution of nearly zero energy buildings (nZEB) has been one of the main drivers for mitigating operational energy consumption in the building industry. The progress was accelerated by the Energy Performance of Buildings Directive (EPBD) in 2010 and since 2018, member states in EU started the obligatory implementation of the nZEB definitions for public and then for all buildings. On the other hand, several studies displayed that the impact of embodied energy originates from the production, transportation and disposal of building materials has become as significant as that of operational energy. However, there is not a consensus of how the embodied energy should be regulated or how it may affect the nZEB definition in the future. In this context, the purpose of this study is to investigate the environmental impact of improved building envelope and technical systems that originates from the nZEB requirements. The study adopted a case study approach to analyze the representative residential and office buildings in Turkiye. By conducting a whole life cycle carbon assessment (wLCA), the embodied and operational carbon emissions were calculated for several building envelope and technical systems scenarios. The results displayed that current nZEB definition increases the embodied carbon by an average of 15 % and decreases operational carbon by 30 % in four different climates. An improved nZEB definition may increase embodied carbon 20 % and decrease operational carbon by 30-80 %. At the end of the study, recommendations were provided for optimal solutions for a low energy building definition for several climate zones and neighbouring regions.