Architect-in-the-loop decision-support framework for zero-energy building-oriented photovoltaic planning at the early design stage

Planning photovoltaic (PV) systems for zero-energy building (ZEB) projects is a design decision-making process that requires coordinating the target energy self-sufficiency ratio (ESSR) with building form, roof use, façade configuration, and visual exposure during the early design stage. This study proposes an architect-in-the-loop decision-support framework that enables architects to examine and coordinate PV planning in early-stage ZEB design. The framework consists of three stages: feasibility assessment, interactive zone determination using solar irradiation color maps and predicted ESSR feedback, and reference layout generation and refinement to provide modifiable alternatives. It was implemented as a computer-based model and evaluated through an exploratory user test with 10 participants experienced in architectural design. After completing an initial massing task for the same office building site in Seoul, the participants used the model to examine PV installation feasibility, installation zones, and layout alternatives. All participants achieved a target ESSR of 20%, with final ESSR values ranging from 20.1% to 25.0%. On a 5-point scale, the solar irradiation map and user-selected zone review functions each received the highest item-level mean score of 4.80, whereas the automatically generated reference layout received the lowest item-level mean score of 3.60. The final PV layouts showed that participants considered not only generation performance, but also roof use, parapet conditions, visual exposure, landscape space, and façade composition. These findings suggest that early-stage PV planning should support architects in interpreting performance feedback and aligning modifiable reference layouts with their design intent, rather than simply presenting a single optimal solution.