Assessment challenges of Zero-emission Buildings: The role of temporal resolution and grid carbon intensity in a monitored European university building

In recent years, the building sector has become a central focus in global decarbonization efforts, highlighting the limitations of traditional energy-only assessments and the need for time-resolved approaches to quantify operational emissions. In the European Union, the EPBD IV revision further reinforces this need by introducing Zero-emission Buildings (ZeBs) and operational-GHG targets. To avoid ambiguity between regulatory compliance and carbon–neutral accounting, this work adopts a dual reporting framework that distinguishes (i) an EPBD-oriented operational emission intensity indicator and (ii) a separate net-emissions balance including explicitly defined compensation terms. An integrated methodology is proposed to assess ZeB performance by formalizing system boundaries, temporal resolution, and emissions accounting rules. The approach is demonstrated on a fully electric university building (946 m 2 conditioned area) equipped with on-site PV generation (40.32 kW) and monitored from 2021 to 2024. Results show that changing the temporal resolution of input data and conversion factors can alter annual net-balance estimates by up to 24 %, with a concurrent reduction of the operational emission intensity from 93.2 to 61.4 kgCO 2,eq /m 2 ·y under coarse aggregation. For improvement strategies, demand reduction and increased PV producibility lead to net-balance reductions of 27.9 % and 24.8 %, while operational emission intensity decreases by about 17 % and 16 %, respectively. These findings confirm the sensitivity of ZeB assessments to methodological assumptions and support the proposed framework as a decision-support tool for robust, comparable and policy-relevant evaluations of building decarbonization pathways.