LIFE CYCLE COSTING OF SUSTAINABLE BUILDING FACADES: A CASE STUDY APPROACH

Abstract

The reality of climate change, the increasing demands of growing cities and the diminishing of natural resources has called for governments across nations to work together to address the global challenges. For many urban cities, sustainable building development has become a priority as buildings are one of the five main users of energy. An innovative method to lower a building’s energy consumption is to incorporate greenery onto the façades of manmade structures including the often forgotten ‘fifth façade’ – the roof. In Singapore vegetation on building envelopes has been coined as ‘skyrise greenery’ (Wong et al., 2002).

Despite the numerous benefits, and the prevalent adoption and encouragement of skyrise greening in Europe and North America, the incorporation of skyrise greenery into building developments in Singapore has yet to be implemented on an extensive scale. Perception studies revealed that local developers are held back partly by concerns for the costs required of skyrise greenery systems. This study aims to investigate the reality and veracity of those concerns, to determine if cost is a concrete or insubstantial barrier to the development and maturation of the local skyrise greening industry. The objectives are to examine the initial cost implications and life cycle costs taking into account the potential cost savings of incorporating skyrise greenery as compared to a conventional building. The scope of the study is limited to extensive green roofs.

11 Tampines Concourse was chosen for this case study. The cost study revealed that both the initial and life cycle costs of the green roof system were significantly higher than those of a traditional roof even with the inclusion of economic benefits in terms of energy cost savings. A simple sensitivity analysis showed that a reduction of 21.47% in green roof construction costs would make the life cycle cost of the green roof less than that of a normal roof, provided all other costs remain unchanged. Limitations of this study include the extent of applicability of the results to other buildings and the inability of the life cycle cost approach to take into account unquantifiable benefits of green roofs. Despite the higher costs, in light of the many social and environmental benefits that green roofs can bring about to our urban city, programs and incentives encouraging the installation of green roofs are highly recommended.