Developing a co-benefits evaluation model to optimize greening coverage designs on university campuses in hot and humid areas

Abstract

The thermal environment of university campuses significantly impacts human comfort and building energy consumption, particularly in regions with hot and humid climates. Optimizing green space can effectively alleviate high-temperature issues and enhance cooling effects ($E_c$), ventilation effects ($E_v$), and carbon sequestration benefits ($C_s$). Given the limited land resources in campus areas, it is critical to optimize the design of green spaces to maximize their multiple benefits. This study aims to propose co-benefits evaluation model for optimizing campus green coverage ratios (GCRs), employing the CRITIC weighting method, while considering multiple evaluation indicators (i.e., $E_c$, $E_v$, $C_s$, and plantation management costs ($M_c$)). This study used ENVI-met software to simulate and quantify the outdoor environmental effects of various GCRs scenarios in a Guangzhou university campus, a typical hot-humid area in China. The model’s accuracy was validated against on-site measurements. Results revealed a parabolic relationship between co-benefits and GCRs. As GCRs increased from 10 % to 47 %, co-benefits gradually decreased from 0.48 to 0.40. Subsequently, with additional GCR increases, co-benefits rose to 0.52, reaching a maximum enhancement of 21.6 %. Moreover, co-benefits improved by about 1.2 % to 9.3 % for each 10% increase in GCR. The GCRs exhibited positive correlations with $E_c$,$C_s$ and $M_c$, and negative correlations with $E_v$. Compared to 10 % GCR scenario, the air temperature, wind velocity, and CO₂ concentration in 90 % GCR scenario decreased by 8.7 %, 44.3 %, and 1.62 %, respectively, and plantation management costs were increased by 90.4 %. This study offers valuable guidance for optimal campus green space design, promoting low-carbon and comfortable educational environments.