Effects of increasing green areas on campus microclimate using InVEST urban cooling model

Urban Heat Island (UHI) is an observed phenomenon worldwide and has a high rising trend. UHI happens when urban areas are significantly warmer than their surrounding rural areas. It is caused by human activities when natural areas are replaced by a dense pavement, built-up, and other surface materials that absorb heat. Consequently, its effects increase air pollution, heat-related illness, energy cost (e.g., cooling system), and especially Greenhouse Gas (GHG) emissions because of more energy consumption. To mitigate the heat island effect and improve community’s resilience, increasing trees plantation or other vegetation, green roof, cool materials, and the use of energy-efficient appliances and equipment can be proposed. King Mongkut’s University of Technology Thonburi (KMUTT) announced on November 2, 2021 the declaration of intent “KMUTT Carbon Neutrality 2040”. So Cool KMUTT program is a part of KMUTT’s policy and measures pathway, aiming to reduce heat island and enhance outdoor thermal comfort.  This study is to investigate the effects of increasing green areas on campus microclimate at KMUTT, Bangmod campus, Thailand using InVEST (Integrated Valuation of Ecosystem Services and Trade-offs) - urban cooling model (InVEST UCM). Remote sensing and GIS are processed by fusion techniques to combine spatial and spectral information. Then, land cover classes are classified by unsupervised classification into eight land cover classes.  Moreover, biophysical metrics data (e.g., shade, albedo, green area building intensity) in each land cover class and evapotranspiration (ET) are provided as input data. Two scenarios (open green spaces and green roof) are applied and compared to the baseline scenario.  By doing this, the campus is assumed to increase green space and green roofs by gradually increasing from 1.0 hectare to 4.0 hectares. The air temperature observed during 23-30 November 2021 from the temporal weather stations within the campus is adopted for model calibration. The results indicate that the open green space scenario shows significantly effect on the air temperature reduction compared to the green roof scenario. The gaps between these two scenarios become greater when the open green spaces will be added. In addition, the cooling effect of two green area scenarios inside the campus also contributes to the surrounding areas. The findings demonstrate that the cooling effect is remarkable within 100 meters away from the campus border. Especially, the green space scenario is able to mitigate high temperatures for both ambient and building temperature which is significantly lower compared to the green roof scenario. The conclusion of this study is that the built-up density at the Bangmod campus is relatively higher than the surrounding areas leading to the campus air temperature being higher than its neighbor. This work compared the cooling effect of two scenarios (green space and green roof) which shows green space scenario is more effective in heat mitigation for both inside and outside the campus. Besides green space solutions, cool material and smart water management can also be considered for heat mitigation. So Cool KMUTT can reduce heat island and mobilize KMUTT to reach the target of Carbon Neutrality by 2040.