Use of vegetation to increase building energy efficiency: application to a real case study

The research here presented deals with the relationship between vegetation and architecture, and how its presence can influence a building project and performance. In the last years, many ways of integrating green in building envelopes have already been experimented, for their potential of reducing thermal loads; the research investigates a specific solution, the vertical forest, which integrates trees and small bushes in specific permanent planters on balconies of high-rise buildings. The main scope is to understand if trees, treated as shadings, can really affect positively the building energy consumptions. Moreover, other aspects, such as trees mechanical stability, construction issues and maintenance are deepened. Through a particular case study, energy consumptions are analysed using dynamic simulations tools, developed with Grasshopper™ and EnergyPlus™ software, in which trees are considered as special external shadings, characterized by a variable permeability to solar radiation during the year. Results demonstrate that trees can contribute to reduce energy loads, depending on species and orientation, especially in association with traditional shading systems. Eventually, some guidelines on technological and construction aspects, as well as on trees species selection, are given, in order to assure the optimal vegetation life and to maximize its benefits on the building.