Emotions are a fundamental part of urban experience and shape preferences, sense of place, and socio-spatial interactions. Among the many factors that influence emotions, urban building façades play a key visual role. Visual disharmony, excessive complexity, or lack of coherence in façade design can create negative feelings such as stress, confusion, or alienation. Balanced and harmonious designs foster positive emotions, like tranquility, visual pleasure, and a sense of belonging. Research has established façades as a crucial visual unit for analyzing emotional responses in cities and shows that environmental feelings form gradually through the scanning of key visual indicators like façades. However, there is still a research gap in clearly classifying specific visual façade components that influence emotions. This study aims to address that gap. It first examines emotion and its theory, then details the façade's visual role, and finally identifies and analyzes the key visual components that shape emotional experiences through attention and visual search.
The research methodology is analytical, using a systematic review of relevant literature. The search covered scientific databases (Web of Science and Google Scholar) from 1960 to 2024 to include historical and current sources. Keywords included terms like "façade sensory perception," "façade feeling," and "visual perception of façade and emotions." The search produced 235 articles; 20 specifically on urban façade emotions were chosen for in-depth analysis. Selection used inclusion and exclusion criteria to ensure direct relevance, scientific rigor, and diversity of approaches.
For analysis, visual components associated with emotional stimulation were first extracted from the selected articles. Synonyms were normalized to ensure terminological consistency. A quantitative content analysis of presence/absence was then performed, leading to the construction of a binary study-by-component matrix. The frequency of each component was calculated from the column sums, with results summarized in a consolidated table. Finally, based on conceptual similarities and alignment with patterns of visual perception—particularly saccadic eye movements and environmental psychology theories—the components were classified into two main categories: "overall façade form" and "façade details".
The findings identified four key components at the first level (overall façade form), which pertain to immediate, holistic perception:
-       Lines: Continuous and curved lines are preferred as they create smooth, deflective paths for saccadic eye movements and reduce cognitive load, unlike discontinuous and sharp-angled lines that induce perceptual conflict.
-       Basic Shapes: Shapes with gentle or right angles are favored due to their congruence with mental schemata, in contrast to shapes with acute angles and unconventional geometric complexity, which impose an unwarranted processing burden.
-       Volume and Massing: Coherent volumes with clear articulation promote legibility and a sense of assurance, whereas irregular projections and recessions disrupt visual unity.
-       Height: Proportionality to the human scale and harmony with the surrounding context induce feelings of balance and cohesion, while stark incongruities can evoke sensations of dominance or vulnerability.
At the second level (façade details), which is processed more meticulously after the overall structure is grasped, three impactful component categories were specified:
-       Element Density: An optimal density (approximately 5-9 distinct elements per façade) is crucial. It provides necessary visual richness while avoiding the boredom of sparse designs or the stress and chaos caused by overcrowding and attentional competition.
-       Visual Variety: Controlled, meaningful variety in elements (type, form, size), color (harmonious palettes with strategic contrast), texture/materials (creating sensory depth), and architectural style (cohesive or thoughtfully integrated) is essential. It maintains visual interest and prevents monotony or extreme disharmony, which leads to confusion.
-       Visual Relationships: This encompasses considered proportions and scale (respecting a hierarchy), arrangement and rhythm (employing regular, symmetrical, or predictable patterns for efficient processing), and the strategic use of contrast and similarity. These relationships primarily affect emotion by modulating the efficiency of attentional deployment and visual search, thereby increasing or decreasing perceptual conflict.
The results clearly demonstrate that, within this framework, the façade and its visual components are not merely physical elements but active mediators between humans and their environment. They evoke various emotions in users by activating attentional and search patterns alongside cognitive predispositions. However, the literature review also indicated that the visual mechanism alone cannot fully account for emotional response. Components such as architectural style, vernacular materials, or cultural symbols—even if formally optimal—may be rejected if they feel alien to collective memory or individuals' mental schemata. Conversely, a façade with minor formal imperfections but that is familiar and meaningful can evoke a deep sense of belonging and security. Moreover, variety in color or materials is enriching only when situated within a coherent narrative or a shared visual language (such as a culturally resonant color palette or a clear structural logic). Therefore, achieving a desirable emotional response to a façade also necessitates careful attention to context, individual and cultural characteristics, personal memories, and collective memory.
Accordingly, a pleasant façade can be defined as one that is both compatible with the physiology of visual perception and aligned with collective memory and individual traits. Adopting this framework elevates the urban designer's role from a mere creator of form to a coordinator and regulator of the user's emotional experience. Their task becomes the intelligent management of a network of variables so that their interaction yields a cohesive and pleasant whole. Undoubtedly, this perspective also requires an interdisciplinary outlook integrating insights from neuroscience, environmental psychology, and aesthetics. Simultaneously, the two-tier classification proposed in this study provides a more structured basis for systematically analyzing the role of façades in citizens' emotional experience and can serve as a foundation for more precise future research. For instance, in early design stages, designers can evaluate overall and then detailed façade characteristics against visual processing mechanisms. By considering factors that affect emotional load—such as increasing or decreasing cognitive processing demands—they can significantly maintain a balance between macro and micro levels. By further incorporating contextual and individual factors, they can enhance the likelihood of evoking a pleasant and positive emotional response to the façade.
Despite these insights, significant challenges remain. First, there is a lack of precise, measurable definitions for concepts like the "optimal level of visual motivation" or the "optimal range of pleasantness" in complex real contexts. Determining context-dependent quantitative thresholds remains a significant theoretical and practical challenge. Second, human emotions in spatial interaction are not confined to the two primary dimensions of stimulation and valence. In real urban situations, a much broader spectrum of emotions—including stress, serenity, boredom, excitement, and more—can continuously emerge and manifest. The prevalent lack of explicit engagement with this diversity in existing studies highlights a critical necessity for future research to progress toward representing the full spectrum of human emotions in urban spaces effectively.