The dynamic thermal conditions profoundly impact on the quality of physical, cultural, and social experiences in courtyard spaces. This research aims to identify the microclimatic dissimilarities between courtyards in terms of tempering seasonal–diurnal thermal extremes and enriching ground-level thermal textures. The methodology included field measurements in summer-2021 and winter-2022 in Cambridge, UK; microclimatic simulations of 107 courtyards in ENVI-met and model validations; and machine learning-driven clustering using Super Organising Maps (SuperSOM). The results indicate that the diurnal thermal range of the spatial-UTCI mean in summer (DTR(M)<24^∘C) is double that in winter (DTR(M)<12^∘C); meanwhile the maximum spatial-UTCI deviation is three times as significant (δ>3^∘Cat 7:00 BST versus δ>1^∘Cat 12:00 GMT). SuperSOM analysis was performed using K-means and hierarchical agglomerative clustering to partition all courtyards into seven subclusters on its graph-lattice structure. Clusters Km_I, Hac_I, and Hac_IV feature a positive synergy between the thermal-tempering and thermal-enriching potentials. In contrast, the other four clusters exhibit conflicting scenarios during the day and night across the two seasons analysed. These data-driven outcomes enabled us to optimise spatial and landscape strategies for designing and retrofitting courtyard microclimates, contributing to the current discussions on climate-responsive and sensation-inclusive design in historical urban contexts. ... Read more

This study set out to understand the dynamics of human thermal sensation and perception associated with outdoor thermal variability in urban contexts. Previous studies found that compact urban forms and green features can contribute to urban climate diversity, and conjectured whether the wax and wane of thermal stress can promote thermal satisfaction in outdoor public spaces. Hence, a stop-and-go method has been developed to accurately capture thermal transitions along urban walks and to provide snapshots of the momentary body thermal sensation and subjective thermal perception. The measurement campaigns carried in late summer involved a total of 40 participants walking for 70 min through two waterfront districts in Rome, Italy. Our findings indicate that: (1) the oscillation of air temperature along the dense urban walk is nearly twice as frequent as that along the sparse suburban walk, due to the microclimatic diversity shaped by the compact urban fabrics, pocket parks and tree-lined river banks; (2) the Universal Thermal Climate Index (UTCI) contrast can effectively predict thermal alliesthesia measured by the rate of change of mean skin temperature, (3) subjective perception shows a significant trend but a poorer model fit predicted by UTCI and; (4) two confounders, view and social backgrounds, are proved to affect the regression model between the objective and subjective data. The conclusions emphasise the importance of incorporating spatial and social contexts into the investigation of outdoor thermal comfort via physiological and psychological approaches. ... Read more

The microclimate shaped by urban form is one of the critical determinants for the success of public spaces. To date, hundreds of studies have revealed the potential of mitigating heat and cold stresses by spatial-enclosure strategies to reduce thermal discomfort. However, most of them have placed more emphasis on taming the thermal extremes, rather than on enriching the microclimatic context to benefit the thermal experience. A rich thermal context with varied, mild thermal stress would enhance psychological adaptation, affording flexibility and meeting different thermal preferences of sun, shade, wind and stillness. Therefore, we aim to investigate the morphological effects on these thermal qualities, and to compare not only the cooling performance of geometries but also the microclimatic diversity and hourly fluctuation in thermal stress. More than a hundred fully enclosed courtyards (n=107) were selected across 31 colleges and 10 teaching sites at the University of Cambridge. We have completed 20-hour microclimate simulations at 33 domains with boundary conditions near the summer solstice and the ENVI-met simulation results were fed back into the heatmap through Urbano, Dragonfly and Ladybug plugs-in in Grasshopper. We found much stronger morphological effects on the variations of sun and wind than on air temperature and humidity. The inferential statistical analysis has also shown that the compacity of building shades and the vegetation configurations play crucial roles in taming thermal extremes and enriching the urban thermal contexts at the human scale. ... Read more