Microclimatic Buffering by Front-Yard Vegetation: Simulation-Based Assessment of Near-Façade Environmental Modulation in Urban Houses

Residential buildings in low-vegetation urban areas are increasingly exposed to heat and air–pollution stress, particularly in suburbs with limited canopy cover near traffic and industrial sources. This study investigates how front-yard vegetation functions as a near-façade microclimatic buffer, moderating outdoor boundary conditions and providing indicative indoor benefits. High-resolution ENVI-met simulations were conducted for a summer day in inner-western Melbourne, Australia, comparing a fully paved front yard (Base) with a vegetated configuration comprising two deciduous trees and boundary hedges (Green). Microclimatic variables at the outdoor and façade boundary scale, including physiological equivalent temperature (PET), mean radiant temperature (MRT), air temperature (T_a), wind speed and façade temperatures (T_ow/T_iw) were analysed. Indicative indoor thermal proxies were derived from ENVI-met′s simplified indoor module to assess relative differences. At peak hour, vegetation reduced PET and MRT near the façade by 17.1°C and 32.7°C, outside wall temperature (T_ow) by 22.0°C, sensible heat flux (H) by 103.1 W/m² and shortwave radiation by 283.2 W/m². Indoor temperature (T_in) proxies showed consistent reductions of 0.1°C–0.2°C, with a cumulative 24-h effect of 1.7°C.h, aligned with façade-scale cooling. Minor changes in T_a and humidity indicate radiative and surface-energy regulation dominate the cooling effect. These results establish front-yard vegetation as a building-scale regulator, modifying façade-level radiative and thermal drivers that influence outdoor–indoor heat and air exchange. The findings establish front-yard greening as a microclimatic strategy under representative hot summer conditions in Melbourne, with broader relevance for low-rise housing in heat-prone, low-vegetation urban areas, motivating future cross-climate studies.