Temporal choices in building LCA: A reporting and diagnostic framework informed by use-phase evidence

Dynamic Life Cycle Assessment (DLCA) is increasingly used to represent time-dependent processes in building assessment. However, the term “dynamic” is used for different forms of temporal modelling, including time-resolved foreground inventories, changing background systems and time-dependent impact characterisation. Studies do not always state clearly which elements vary with time, at what resolution or how they are linked, limiting methodological interpretation and comparison. This study develops a structured framework from a critical methodological review of building use-phase DLCA, with emphasis on non-domestic applications. The review examines temporal treatment across foreground inventories, background systems and Life Cycle Impact Assessment, as well as coupling-rule transparency, timestep justification, data quality and implementation constraints. The synthesis shows that time-varying foreground data are reported more often than temporally differentiated background systems or characterisation methods, while coupling rules and resolution choices remain inconsistently documented. The proposed framework records where and how time is represented and supports assessment of whether those choices are appropriate to the stated goal, scope and time horizon. A worked non-domestic operational-electricity application demonstrates the framework across three configurations combining annual or hourly demand with annual-average or monthly grid carbon-intensity factors. Monthly matching reduced annual operational-electricity GWP from 812.72 to 754.11 kg CO₂-eq/year, a reduction of 7.21%. These results illustrate the influence of temporal matching within the defined one-year operational-electricity boundary; they do not represent a complete module B6 life-cycle assessment or rank DLCA methods.