Applicability of the adaptive thermal comfort model in naturally ventilated high-rise residential developments in Colombo, Sri Lanka

Abstract

This study investigates the applicability of the ASHRAE 55-2017 adaptive thermal comfort model in naturally ventilated high-rise residential developments in Colombo, Sri Lanka, where rapid urbanization and tropical climatic conditions pose unique challenges for low-income communities. While international standards like ASHRAE 55-2017 provide frameworks for thermal comfort, their relevance in resource- constrained, high-density tropical housing remains underexplored. To address this gap, the research employs a mixed-methods approach, combining longitudinal field measurements of indoor environmental parameters (temperature, humidity, air velocity) with detailed occupant surveys to capture subjective comfort perceptions and adaptive behaviors across five case-study buildings. The results reveal critical discrepancies between model predictions and lived experiences: occupants reported 94.5% dissatisfaction with indoor thermal conditions, despite employing adaptive strategies such as fan use and window adjustments. These differences are aggravated by vertical microclimatic variations, with upper-floor residents experiencing significantly different thermal conditions than lower floors, and socio-cultural constraints, such as privacy concerns that limit effective natural ventilation. Statistical analyses, including Spearman’s rank correlation and ANOVA, further demonstrate that the ASHRAE model underestimates the adaptive capacity of residents in warm- humid climates, particularly during peak discomfort periods (e.g., midday, when 64% of respondents reported severe thermal discomfort). The study concludes that the ASHRAE 55-2017 model requires context-specific recalibration for tropical high- rises. It proposes revised adaptive comfort criteria and emphasizes targeted architectural interventions, such as optimized cross-ventilation and solar shading, alongside policy reforms to address thermal equity in low-income urban housing.