Comparative Analysis of Passive Cooling in Dense Urban Housing Blocks

Thesis Abstract

Urban heat challenges in dense, low-rise and mid-rise residential blocks in rapidly urbanizing cities have intensified energy use for cooling and compromised indoor thermal comfort, particularly for vulnerable populations in informal and transitional settlements. This study addresses the gap in comparative evidence on the effectiveness of passive cooling strategies across heterogeneous dense urban housing blocks, aiming to identify design, urban form, and materials factors that yield measurable reductions in indoor temperatures and cooling loads without reliance on mechanical systems. The objective is to evaluate and compare passive cooling performance across three typologies—courtyard-based mid-rise blocks, narrow-alley terrace housing with cross-ventilation, and high-density stacked flats—under hot, humid subtropical climate conditions. Specific objectives include (1) documenting architectural configurations, facade treatments, vegetation integration, and microclimate indicators; (2) quantifying indoor thermal performance using monitored data and simulated predictions; (3) examining occupant comfort, behavioral adaptations, and interaction with passive strategies; (4) assessing cost-effectiveness and scalability of passive cooling solutions; and (5) deriving design recommendations and policy implications for retrofit and new-build practice. The methodology adopts a mixed-methods embedded design grounded in the theory of bioclimatic architecture and the urban heat island concept. A cross-sectional field study will be conducted in three representative urban precincts within a metropolitan area, with a total housing stock sample of 240 dwellings stratified by typology. Data collection combines quantitative monitoring and qualitative inquiry (i) continuous indoor air temperature, relative humidity, and natural ventilation rates over a six-month period using data loggers (n = 720 sensor-weeks across dwellings); (ii) exterior microclimate measurements (WBRT, globe temperature, solar radiation) at each site; (iii) occupant surveys (n = 300 adults) to capture thermal perception, clothing insulation, and behavioral practices; (iv) daylighting and thermal mass measurements in a sub-sample (n = 60 units); and (v) architectural documentation and material analyses through laser scanning, thermography, and material property tests. Analytical techniques include multilevel regression to isolate the effects of architectural variables (courtyard presence, facade porosity, roof overhangs, insulation levels) on indoor operative temperature and cooling degree-hours, ANOVA to compare performance across typologies, and SEM to test the relationships among microclimate, occupant comfort, and retrofit viability. The study also employs a comparative simulation approach using EnergyPlus and Rhino+Grasshopper to validate measured data against modeled outcomes, with calibration based on 30 validation cases. Expected findings indicate that courtyard-based mid-rise blocks with high façade porosity, substantial solar shading, and integrated vegetation will achieve lower indoor temperatures and reduced cooling loads relative to narrow-alley terraces lacking cross-ventilation, with improvements sustained under peak afternoon heat. The terrace typology is anticipated to perform well where cross-ventilation corridors are unobstructed and thermal mass is effectively employed, while stacked-flat configurations may require targeted shading and enhanced ventilation pathways to achieve comparable comfort gains. The research is likely to reveal synergistic effects between microclimate enhancements (shade, wind corridors) and building envelope strategies (cool roofs, high-reflectance materials, breathable insulation), yielding the greatest reductions in measured operative temperatures and occupant discomfort indices. The study expects to demonstrate cost-effective retrofit packages, with payback periods under seven years for moderate interventions in mixed-income neighborhoods. Contributions to knowledge include (1) a robust, comparative empirical assessment of passive cooling performance across urban housing typologies in a densely built setting; (2) a transferable framework linking form, materiality, microclimate, and occupant behavior to thermal outcomes; (3) evidence-based design guidelines for architects and planners to optimize passive strategies within existing city fabric; and (4) policy implications for building codes and retrofit funding that prioritize passive cooling as a frontline strategy. The main conclusion anticipates that well-integrated passive cooling strategies can materially reduce indoor temperatures and energy demand in dense urban housing blocks without reliance on active systems, contingent on thoughtful typology-specific design, climate-responsive detailing, and occupant engagement. Recommendations emphasize early-stage typology selection, deployment of shading and ventilation corridors, incorporation of high-reflectance materials and breathable insulation, and investment in occupant education to maximize behavioral benefits.