The object of research is a narrow vertical solar chimney designed for passive building ventilation, specifically focusing on the interplay of geometric and operational parameters within the narrow chimney regime (gap-to-height ratio ≤ 0.2). The purpose of this work is to systematically optimize the absorber height, air gap (set equal to the inlet height), and solar radiation intensity to maximize the volumetric airflow rate and air changes per hour (ACH), thereby providing a computationally efficient alternative to complex numerical simulations. Method. A steady-state analytical model, solving coupled energy balances for the glass cover, air stream, and absorber wall, was developed and implemented as a rapid, open-source predictive tool in Python. The model was first validated against established theoretical data, yielding a mean absolute percentage error of 5.3% (R² = 0.98). Subsequently, a Taguchi L16 orthogonal array was employed to evaluate the main effects of the selected parameters (absorber height: 800–1500 mm; air gap/inlet height: 50–150 mm; solar radiation: 250–700 W/m²), followed by Analysis of Variance (ANOVA) to quantify their statistical significance and relative percentage contributions. Results. The ANOVA revealed that the air gap is the most influential factor, contributing approximately 68% to the total variation in airflow, followed by solar radiation intensity (17%) and absorber height (14%). The optimal configuration for maximizing ventilation within the studied design space corresponds to the highest tested levels of all three parameters (1500 mm height, 150 mm gap, and 700 W/m²), yielding a volumetric flow rate of 0.0307 m³/s (approximately 4.1 ACH for a 27 m³ room). The findings confirm that, for narrow chimneys, monotonically increasing the air gap and inlet height while keeping them equal consistently improves performance, validating empirical design recommendations and establishing a robust, fast predictive framework for small-scale solar chimney optimization.

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