Modeling the Impact of Vegetation Dynamics on Urban Microclimate and Building Energy Demand

Urban green infrastructure (e.g., lawns, trees, green roofs) is a critical nature-based solution for mitigating urban heat island effect and reducing building cooling energy demand. While its biophysical processes, such as evapotranspiration, shading, and photosynthesis, are known to modify local microclimate and surface-atmosphere exchanges, most existing assessments rely on simplified, static representations of vegetation. This overlooks essential dynamic processes such as seasonal growth, phenological changes, greening-browning shifts due to heat and moisture stress responses, leading to uncertainties in quantifying its full cooling and energy-saving potential. To address this gap, we develop and apply an enhanced Urban Canopy Model (UCM) that integrates a dynamic ecohydrological module for vegetation with a building energy model capable of simulating outdoor thermal conditions and anthropogenic heat emissions. We first conducted comprehensive field campaigns in Wuhan, China, using a newly established urban eddy covariance tower and a green roof monitoring system, coupled with data on irrigation and other anthropogenic activities within the flux footprint. The model was rigorously validated against measurements of air/soil temperature, moisture, and turbulent heat fluxes. We then performed sensitivity analyses to evaluate how dynamic vegetation parameters (e.g., soil moisture, vegetation greenness, irrigation regimes) and building properties interactively affect outdoor microclimate and indoor energy demand. Our findings demonstrate that accounting for vegetation dynamics significantly improves the accuracy of microclimate and energy simulations, providing actionable insights for the planning and optimization of green infrastructure towards energy-efficient and climate-resilient cities.