NCC 2025 introduces important changes to J1V3 reference-building modelling for commercial and non-residential projects. These changes affect the performance threshold, envelope comparison, thermal-condition tests, climate data, operating profiles and treatment of on-site solar photovoltaic systems.

An NCC 2022 JV3 model cannot simply be carried forward and relabelled as an NCC 2025 assessment. The applicable code edition, jurisdiction and modelling basis should be confirmed before the model is updated. For a broader explanation of the underlying method, visit the JV3 Knowledge Hub.