A joint document published by REHVA and SHASE presents an overview of how the European Union and Japan are advancing towards buildings with minimal operational emissions. The report reviews the regulatory evolution in both regions, noting the EU’s shift from Nearly Zero Energy Buildings to Zero Emission Buildings under the 2024 Energy Performance of Buildings Directive  (EPBD) recast, and Japan’s long‑standing ZEB framework established through its Energy Conservation Act.

The report compares the EU’s ZEB definition—requiring at least a 10% reduction in primary energy compared with NZEB levels and the elimination of on‑site fossil fuel emissions—with Japan’s tiered system. Japanese classifications range from ZEB Oriented to full ZEB, based on reductions in normalised primary energy demand and the contribution of on‑site renewable generation.

The two case studies illustrate how these definitions are applied in practice. The European examples include a multifamily building assessed across three different climates, showing variations in heating and cooling needs and the influence of photovoltaic self‑consumption. The Japanese case focuses on an office building in Sapporo, a cold region, demonstrating how annual calculations and the full deduction of on‑site renewable generation affect the building’s energy index. These two case studies serve to highlight the practical implications of the respective methodologies.

In its concluding section, the report identifies future challenges for both regions, including the integration of off‑site renewable energy, the need for harmonised assessment boundaries, and the development of indicators that reflect grid interaction and building flexibility. It emphasises that these issues will shape the next phase of zero‑emission building policy and evaluation.