Evaluating the role of urban trees on building energy use: a global literature review

Abstract

As the global energy crisis and climate change exacerbate urban heat island effects, trees offer significant potential to reduce energy demand by shading solar radiation and improving microclimates. However, there is a lack of comprehensive global reviews on the effects of urban trees on building energy use. This study aims to address the existing research gap by systematically reviewing peer-reviewed literature to investigate the impact of urban trees on building energy use across global climate zones, analyzing the mechanisms and pathway combinations through which trees influence energy use, and exploring optimal tree placement strategies for building energy performance optimization. Results show that trees can reduce cooling energy use by up to 60 %, with savings ranging from 31.75 % in equatorial climates to 4.78 % in snow climates. The impact on heating energy use varies widely, from −63.8 % to 45 %, depending on climate, tree species, and placement. Simulation studies analyze more complex pathway combinations (9 types) compared to empirical research (4 types), revealing methodological gaps in empirical studies of these mechanisms. Spatial analysis shows latitude-dependent optimization patterns, where for cooling, 38.5 % of studies recommend west-side planting while 23 % suggest south-side planting (though less effective at low latitudes). The optimal planting distances cluster at 3 m and 5 m for both cooling and heating effects, with high-latitude cooling extending to 9–12 m spacing. Future research should integrate interdisciplinary approaches, AI modeling, and high-resolution monitoring data to optimize tree-building energy interactions.