Decoupling Size-Cooling-Comfort linkages: A parsimonious approach for analysing biophysical cooling capacity and outdoor thermal comfort perception in public urban parks

Using parsimonious approach, this study develops a novel framework integrating outdoor thermal comfort (OTC) perception and biophysical park cooling capacity (PCC). OTC perception is measured through Apparent Temperature reduction (ΔAT) between park and its surrounding built environment using microclimatic data of temperature, relative humidity and wind speed. Given the established positive correlation between subjective and objective thermal comfort measures in prior research, this study adopts ΔAT as a proxy for OTC. Unlike predominant models that rely on simple temperature differences (e.g. park cooling intensity), this study employs an enthalpy-based method to estimate PCC. This method accounts for both sensible and latent heat exchanges, providing a more comprehensive estimation of park cooling load. This study confirms that larger parks possess greater cooling capacity. However, it contests the transitive assumption that increased park size enhances OTC perception. This study also points to a decoupling effect of park size, since it does not correlate significantly with OTC perception. Moreover, partial correlation analysis further reveals that park size acts as a confounding variable, masking the true relationship between PCC and OTC perception. To better assess the cooling efficiency of urban parks, the study develops a Park Cooling Performance Index (PCPI) by evaluating OTC perception relative to PCC per unit area. Notably, small-sized urban parks outperformed larger ones. These insights thereby address a paradigm shift in urban greening strategies. Prioritizing and designing compact, vegetated, small-sized urban parks as natural cooling systems can improve local microclimate and climate resilience, particularly in highly-dense, hot-humid, tropical Indian cities.