Perceptual and physiological virtual assessment of indoor Living Walls including lighting settings

• VR prototype to assess Living Wall lighting-comfort interaction before real installation • Three virtual classroom tested: Baseline, Living Wall, Living Wall with shielded LEDs • Horticultural LEDs raise perceived brightness and glare but not physiological stress • Shielding keeps PPFD for plants while preserving visual comfort and physiology • High ecological validity and negligible cybersickness confirm IVE prototyping value Living Walls (LWs) are increasingly introduced to improve air quality and aesthetics indoors, but the supplementary lighting required for plant vitality can disrupt occupant comfort. Thus, LW design should adopt an integrated approach, combining system requirements definition with users’ comfort. Immersive Virtual Environments can support LWs prototyping, reliably creating and comparing alternative design scenarios. This study proposes a modular LW and employs virtual scenarios as a pre-design strategy to evaluate the influence of different configurations on users’ visual perception and physiological state. The baseline scenario without greening is compared with the simple LW implementation (LW scenario) and with LW integrated by specific horticultural lighting, installed on an overhead supporting bracket, and properly shielded to ensure a proper work plane illuminance (LWL). The system is applied to a virtual university classroom, modelled and validated in respect of its real-world conditions. 41 subjects experienced each virtual scenario in a repeated-measure design study, rating realism, task suitability, visual comfort, and configuration preference, while physiological parameters were also monitored. Statistical analysis revealed a high realism in all scenarios, and similar perceived quality levels for task suitability. LWL, as expected, was perceived as 30% brighter, 25% more glare than baseline and LW, but physiological and eye-tracking metrics remained stable across scenarios, confirming no stress-related implications, thanks to proper trade-offs between LW design and dedicated lighting implementation. Presence in virtual scenarios was high and cybersickness negligible, validating the ecological fidelity, supporting the potential of this multi-step, user-centred methodology for optimising biophilic interventions during the pre-design phase.