The true cost of “greening” a building: Life cycle cost analysis of vertical greenery systems (VGS) in tropical climate

Abstract

Increasing number of building owners is adopting vertical greenery system (VGS) as an alternative to building facades or claddings due to its environmental, aesthetic and social benefits in recent years. While numerous studies have been conducted on its potential benefits and its environmental impacts, there has been little focus on its life-cycle cost (LCC) which is a crucial factor for building owners to adopt a VGS as well as to compare among various types of system. To fill this gap, this study aims to identify and calculate the LCC of 3 main types of VGS available in Singapore, where is the tropical climate, namely the carrier, planter and support systems. The cost incurred during each life-cycle stage including initialisation, installation, operation and demolition, are recorded based on 8 completed and ongoing cases selected in Singapore. The analysis of the results shows that the support system has the lowest life-cycle cost (S$885) followed by planter (S$3,786) and then the carrier system (S$4,919). During the life-cycle, the stage of Operations and Maintenance contributed the most to the LCC of a VGS (73.7–83.9%), while plants related parameters, e.g. plant replacement rate and price, affect the largest variances of LCC. for the support system, the LCC of VGS can be balanced off by building energy cost savings within 30 years, but not for other two systems. Suggestions on selecting VGS types, plants and supporting structures to reduce the cost of VGS have been discussed to conclude the study.