Assessing Passive Cooling Performance in Urban Residential Courtyards: A Field Study

Thesis Abstract

Urban heat islands and rising cooling energy demands in dense city cores necessitate practical, low-energy strategies for thermal comfort in residential spaces. This study addresses the limited empirical understanding of how passive cooling in urban residential courtyards contributes to thermal comfort and energy savings, particularly under varying microclimatic and architectural configurations. The aim is to quantify passive cooling performance of courtyard Design Typologies and to identify which courtyard features most effectively reduce indoor and outdoor temperatures, while enhancing occupant comfort and reducing cooling loads. Specific objectives include (1) to characterize microclimate conditions (air temperature, mean radiant temperature, relative humidity, and wind flow) within and around urban residential courtyards across four distinct typologies; (2) to evaluate the relationship between courtyard geometry (size, aspect ratio, and enclosure density), vegetation cover, water features, and surface materials on thermal performance; (3) to assess occupant thermal comfort and perceived usability of courtyards through seasonal field surveys; (4) to estimate potential energy savings from passive cooling strategies by comparing monitored data with baseline indoor cooling loads derived from building simulation; and (5) to develop an evidence-based guideline for courtyard design that optimizes passive cooling in tropical to temperate urban contexts. The methodology adopts a mixed-methods research design anchored in a positivist-interpretivist blend to capture objective microclimatic data and subjective comfort perceptions. The population comprises Vernacular and contemporary low-rise residential blocks within three metropolitan districts exhibiting varied courtyard typologies. A stratified purposive sample of 120 courtyards, representing four typologies (rectangular central courtyards, perforated facades with internal courtyards, terraced courtyard clusters, and green screens with sheltered atria), is selected. Data collection instruments include (i) thermochromic and aspirated psychrometric sensors for continuous one-year microclimate monitoring (hourly air temperature, relative humidity, wind speed, and globe temperature), (ii) infrared thermography for surface temperature mapping, (iii) light and solar exposure meters to assess radiative heat gains, (iv) a standardized occupant survey instrument adapted from ASHRAE Thermal Comfort and ISO 10537 for seasonal assessments, and (v) semi-structured interviews with residents and facilities managers to capture perceived usability and maintenance considerations. Validity and reliability are strengthened through cross-validation of sensor data with independent weather station records, calibration of instruments before deployment, and a pilot test of the survey instrument with 20 households. Data analysis employs (a) descriptive statistics and time-series analysis to delineate diurnal and seasonal patterns; (b) multivariate regression and generalized additive models to quantify the influence of courtyard geometry, vegetation density, water presence, and albedo on microclimate parameters; (c) ANOVA to compare thermal performance across typologies; (d) structural equation modeling to link courtyard design variables with occupant comfort outcomes; (e) computational-fluid-dynamics-informed kinematic analysis for local wind flow patterns; and (f) a simple energy balance model to estimate potential reductions in cooling demand. The study integrates theory from bioclimatic design and the Microclimate Theory of Urban Form, and draws on the Thermal Comfort framework (CBE Temperature/Predicted Mean Vote) to interpret occupant responses. Expected findings indicate that higher vegetation density and water features correlate with lower mean radiant temperatures and moderated peak indoor temperatures, with a notable reduction in cooling energy demand—estimated at 12–28% depending on typology and climate year—when compare to conventional courtyards lacking shading and greenery. Rectangular courtyards with higher enclosure density and cooler surface materials are expected to show greater diurnal temperature stability, while perforated and terraced configurations may exhibit enhanced ventilation benefits under prevailing wind regimes. Occupant comfort scores are anticipated to align with objective measures, with thresholds varying by season and occupancy patterns. The anticipated contribution to knowledge includes a robust empirical dataset linking specific courtyard design variables to measurable microclimate and comfort outcomes, filling a critical gap in architecture and urban design literature for field-based passive cooling in dense urban fabrics. The study offers a practical design guideline with configurable parameter sets for courtyard typologies, enabling practitioners to optimize passive cooling without reliance on mechanical systems. The main conclusion will emphasize the feasibility and effectiveness of optimized courtyard design as a viable strategy for thermal comfort and energy savings in urban residential settings. Recommendations include (i) adopting a typology-informed design toolkit that prioritizes shading, ventilation corridors, and water features; (ii) integrating vegetation with native, climate-adapted species to sustain reflective surface temperatures; (iii) incorporating wind-aware planning and permeable enclosure strategies to maximize cross-ventilation; and (iv) implementing routine monitoring protocols for maintenance to preserve performance, with implications for building codes and urban design guidelines. Suggestions for future work propose longitudinal studies across different climate zones, incorporating occupant behavior dynamics and Life Cycle Assessment to quantify broader environmental impacts.