The impact of vertical vegetation on thermal performance of high-rise office building facades in Mediterranean climate

Abstract

Nowadays, vertical greenery systems are considered as a promising solution for improving energy efficiency, while providing environmental and socio-economic benefits. However, a literature gap regarding their quantitative effects on building’s thermal performance exists. The main aim of this paper is to initiate an analytical approach towards evaluating the greenery effectiveness in reducing the energy loads and improving the indoor thermal comfort, contributing to the current body of knowledge. The main novelty and scientific significance consist of evaluating different design strategies of green facade and shading systems, widely implemented on building envelopes, even though no previous study has provided scalable results regarding their efficiency. Several design variables including WWR (window-to-wall ratio), LAI (leaf area index), and plant height are selected for a comprehensive whole-building energy performance analysis. The results highlight the efficiency of vegetation strategies on opaque walls achieving a significant range of energy reduction from 9% up to 11% for 50% window-to-wall ratio scenarios and from 3% up to 6% for 70% window-to-wall ratio scenarios, with 1 °C up to 2 °C indoor air and mean radiant temperature increase in the winter period. Additionally, the impact of vertical greenery effectiveness on a fully glazed building scenario, rarely mentioned in previous studies has been proved, providing a considerable reduction of 4.7 °C indoor air temperature and 9 °C radiant temperature in the summer period, ranging from 14% up to 34% energy savings. The performed simulation results generate a fundamental framework towards early design decision-making stages.