Impact of Architecture Façade Design on Neurophysiological Stress Using Functional Near-Infrared Spectroscopy and Heart Rate Variability

Within industrialised and emerging industrialised economies people typically spend over 95% in industrialised and emerging industrialised economies typically spend over 95% of their time in built environments, yet the neurophysiological impact of architectural design remains poorly understood. While previous studies link visual patterning to cortical activity, the cortical-to-autonomic stress pathway remains largely unexplored—a key omission given that chronic stress contributes to allostatic overload. This study examined how architectural façade design influences neurophysiological stress through a multimodal approach combining functional near-infrared spectroscopy (fNIRS) to monitor occipital cortical activity with heart rate variability (HRV) as an index of autonomic regulation. Eighteen participants provided HRV data and subjective ratings for nine systematically varied façade images characterised by their deviation with respect to natural statistics, while a subset of twelve completed fNIRS recording due to signal acquisition constraints. Façade identity significantly affected discomfort, complexity, and interest ratings (p<0.001), and deviation from natural statistics predicted all three measures (p<0.01). Façade type also showed a small but significant effect on HRV (p=0.003), although variance was dominated by individual differences. No stimulus-specific occipital fNIRS differences were observed. However, due to the limited sample size, further research is needed to verify this observed result. Whilst global generalisations cannot be drawn due to the small sample size, these pilot research findings indicate that façades deviating from natural image statistics influence perceptual comfort and may modestly modulate autonomic balance. However, the present data does not provide clear evidence of stimulus-specific cortical effects, which, if present, likely remain below the detection thresholds of the current protocol given its methodological constraints. This study highlights methodological hurdles and establishes a scalable framework for linking computational visual metrics to physiological responses, informing future investigations into how architectural features influence human health.