Sustainable Transition from nZEB to ZEB in a Northern Climate: Annual Energy Performance and Whole-Life Carbon Implications of Passive and Renewable Design Choices

The recast Energy Performance of Buildings Directive (EPBD) accelerates the transition from nearly zero-energy buildings (nZEBs) to zero-emission buildings (ZEBs), requiring solar readiness and life-cycle Global Warming Potential (GWP) disclosure. Yet operational performance, future-climate adaptation and whole-life carbon (WLC) are still often assessed separately, limiting actionable evidence for residential ZEB design in northern climates. This study provides an integrated design-decision framework coupling annual IDA-ICE simulations under five weather scenarios, including Urban Heat Island (UHI)-adjusted present and 2080 RCP8.5 + UHI files, with an EN 15978/Level(s)-based WLC assessment in One Click LCA for twelve design cases of a Lithuanian dwelling. For the PV-equipped baseline, heating electricity decreases by 24% and cooling increases by 31% from present conditions to 2080 RCP8.5 + UHI. External shading and night purge provide the strongest annual cooling and operative-temperature-exceedance reductions. The ZEB baseline reduces WLC by 19.0% relative to A0; the biogenic-insulation green-roof case gives the lowest non-storage WLC (−25.2%); and battery-assisted cases provide the largest reductions under the static B6 electricity factor (up to −52.1%). The findings provide case-study evidence that EPBD-aligned residential ZEB design should evaluate passive cooling, PV/storage and material choices jointly, rather than sequentially, when developing future performance thresholds and design guidance.