Abstract Over the past decades, intense urbanization processes have produced built environments with a low energy efficiency and a severe lack of green spaces, which represent the main providers of ecosystem services in cities and play a relevant role in regulating the local microclimate. Among the different natural processes involved in climate regulation, a fundamental role is played by the shading effects of urban vegetation on buildings and built environment. Consequently, urban planning strategies aimed at designing a Green Infrastructure (GI) can have significant impacts on reducing the summer-time energy demand of cities while providing new green spaces for the local community. This is particularly relevant in high density settlements, where urban morphology types such as multi-storey apartment buildings represent an important percentage of the entire built environment. For these morphology types, the implementation of the GI depends on the different possibilities and limitation offered by private open spaces around residential buildings. Despite its importance, the implementation of a GI from public administrations must often challenge the lack of economic resources to acquire and manage private land to be set as new urban green spaces. This article investigates the potential energy savings for multi-storey apartment buildings that can be achieved by shading effect of trees. Particularly, building performance simulations are carried out considering different configurations of key parameters, such as trees species, distance to buildings, orientations of buildings and actual room of open spaces beside buildings where to plant new trees. The simulations are run for a real urban case study located in the metropolitan area of Catania in southern Italy, characterized by different types of urban morphologies. Simulations of shading effect consider three species of trees and 41 different spatial configurations depending on actual availability of open spaces around buildings. Results show that relevant energy savings can be obtained when the entire facades of buildings are shaded. The range of reduction of cooling loads of buildings varies between 2% and 50%, depending on the species and configurations: for half of considered 41 configurations 15% of average reduction is obtained. From an urban design point of view, results also suggest that the distance of trees from buildings and the actual availability of room for trees are key aspects to consider when designing where and how to plant new trees. Not in all configurations simulated, planting trees can result in a significant reduction of cooling energy loads. Findings of this work support urban planning for the choice of different scenarios and alternatives of GI to better balance public and private costs and generate wider benefits for the local communities.