The operational energy efficiency of new buildings in the EU should be at the level of ultra-low or near-zero energy buildings. It is therefore relatively difficult to achieve further energy savings. However, the pre-operational phase—raw material sourcing, manufacturing, transportation, and construction—offers significant energy savings and greenhouse gas reduction opportunities, referred to as embodied energy and equivalent CO₂ emissions. Unlike operational energy, no standard or legislative criteria have yet been established for embodied energy. Setting maximum embodied energy values converted to the unit of heated building area, accounting for building shape factor, and differentiating between high-mass and lightweight constructions are proposed. This study illustrates assessing environmental indicators based on building shape, highlighting the necessity of relative assessments over absolute values to favour energy efficiency. It also emphasizes that precise criteria should derive from authentic data collected during the energy certification and building permitting processes. Integrating assessments of embodied energy and operational energy demand facilitates a comprehensive evaluation of buildings’ environmental performance.

This study investigates the influence of geometric parameters—size, proportions, number of floors, and roof shape—on the environmental efficiency of family houses using a simplified life cycle assessment (LCA) method. The analysis focuses on the product stage (A1–A3), commonly referred to as “cradle to gate,” which encompasses embodied emissions and energy. It demonstrates that even within the limited scope of the product stage (A1–A3), geometric parameters such as floor area, proportions, and compactness exert a decisive influence on embodied environmental impacts. In addition to absolute and per-square-meter indicators, the analysis highlights the importance of the shape factor, defined as the ratio of envelope area to heated volume, as a fairer basis for comparing buildings of different geometries. Similar to its established role in operational energy certification, the shape factor provides a meaningful link between geometry and embodied impacts. The findings suggest that future implementation of the Energy Performance of Building Directive IV (EPBD IV, EU 2024/1275), which mandates the calculation of the global warming potential (GWP) of new buildings from 2028 onwards, could benefit from evaluating both primary energy non-renewable (PENRT) and global warming potential (GWP) in relation to the shape factor, once sufficient data become available. The presented study thus contributes to the ongoing European debate on whole-life-cycle carbon assessment while clarifying its novelty as a geometry-based, product-stage method that can be scaled and adapted to different contexts. The proposed simplified, geometry-oriented approach to estimating embodied impacts (A1–A3) with shape factor-based normalisation enables a fair comparison of buildings with different geometries at the concept stage.