Comparative Analysis of Passive Cooling in Urban Housing Blocks Across Cities

Thesis Abstract

Urban housing blocks in rapidly urbanizing regions face rising thermal loads that undermine occupant comfort and energy efficiency, challenging the viability of conventional cooling strategies and highlighting the need to optimize passive cooling potentials across different urban contexts. This study addresses the gap by comparing passive cooling performance in urban housing blocks across three distinct cities with similar climatic zones but varying urban morphology, building typologies, and material practices. The aim is to identify how design, microclimate, and occupancy patterns influence passive cooling effectiveness, and to develop a transferable framework for urban housing that enhances thermal comfort while reducing energy demand. Specific objectives are to (1) quantify indoor thermal performance under typical occupancy schedules using standardized measurement protocols; (2) evaluate the influence of façade orientation, shading devices, thermal mass, natural ventilation rates, and urban canyon effects on cooling potential; (3) compare outcomes across cities to discern context-dependent drivers and barriers; (4) test the applicability of established theories of passive cooling—namely, the Adaptive Comfort Theory and the Principle of Thermal Mass Optimization—within cross-city settings; and (5) propose a set of design guidelines and policy recommendations for permeable urban housing blocks that optimize passive cooling without reliance on mechanical systems. The methodological approach combines a cross-sectional comparative research design with mixed methods. The population comprises mid-rise residential blocks constructed within the last two decades in City A, City B, and City C, each with homogeneous block typologies and climatically comparable conditions. A stratified multi-stage sampling strategy selects 30 blocks per city, totaling 90 blocks, with 6 sub-units (flats) per block and 3 monitoring zones per block to capture variability within microclimates. Data collection instruments include calibrated data loggers for indoor air temperature, relative humidity, and operative temperature, outdoor microclimate sensors for ambient temperature and wind, plus portable anemometers to measure natural ventilation rates; occupant surveys capture thermal comfort votes and behavioural adjustments. Architectural and urban form variables are recorded through standardized checklists and building information modeling (BIM) data. Validity and reliability are ensured via pre-tested instruments, inter-rater calibration for observational data, and repeat measurements across two heating/ cooling diurnal cycles. Data analysis employs a multilevel hierarchical linear modeling (HLM) framework to assess the influence of block-level (façade shading ratio, glazing-to-wall ratio, thermal mass, and local wind corridor) and city-level factors (climate data, urban morphology) on indoor operative temperatures and comfort indices. Regression analyses identify key predictors of thermal comfort, while ANOVA tests differences in passive cooling performance across cities. Thematic analysis of occupant interviews examines behavioural adaptations and perceived constraints, triangulated with quantitative findings. A conceptual model integrates Adaptive Comfort Theory with Thermal Mass Optimization to interpret cross-city variations. Expected findings indicate that blocks with higher shading, optimized cross-ventilation paths, and substantial thermal mass in conjunction with favorable urban canyons demonstrate significantly lower indoor temperatures (mean reduction of 1.5–2.5°C) and higher adaptive comfort satisfaction (average comfort vote above 0.5 on a seven-point scale) compared with blocks lacking such features. Cross-city comparisons are anticipated to reveal that urban morphology and wind corridor presence mediate the effectiveness of passive cooling strategies, with City B showing superior performance due to a more favorable street canyon orientation and material choices. The study would also delineate context-specific thresholds for design parameters—such as required shading ratios and thermal mass ranges—to achieve acceptable comfort without mechanical cooling. The study contributes to knowledge by providing an empirical cross-city evaluation of passive cooling performance in urban housing blocks, refining the applicability of Adaptive Comfort Theory and Thermal Mass Optimization in diverse urban contexts, and delivering an transferable design framework and policy guidance for architects, planners, and housing authorities. Practical recommendations include standardized performance benchmarks, recommended façade and courtyard configurations, shading device typologies, and guidelines for material selection aligned with local climate and urban form to maximize passive cooling potential and minimize energy consumption. The research concludes that context-aware passive cooling design, underpinned by robust empirical data and a clear analytical framework, can substantially improve thermal comfort in urban housing while reducing reliance on mechanical cooling.