Sensitivity analysis of design variables in life-cycle environmental impacts of buildings

Abstract

Buildings are responsible for a large portion of global energy consumption and carbon emissions. Improvements in building design contribute to reducing environmental impacts of buildings. In this context, a crucial issue is to understand which design variables should be considered while which variables could be negligible. The objective of this study is to develop a framework for assessing the influence of various design variables throughout the design process in the environmental impacts of a building over its life cycle. This methodological framework combined building information modelling and life cycle assessment tools and a global sensitivity analysis using the Morris elementary effects method. A residential building was applied to demonstrate the developed framework. The influence of six design variables in early design stages (including, floor area, aspect ratio, floor height, orientation, window-to-wall ratio and number of floors), nine variables in detailed design stages (including, structure type of external and internal walls, type of insulation material for external and internal walls, insulation material for floors, waterproofing and insulation material for roof, type of window frame, and glazing type), and four variables in construction design stages (including, type of finishing for external walls, internal walls and floors, and roof tiles) are examined. Three environmental impact criteria (including, embodied, operational, and life-cycle environmental impacts) of a building are considered. The results identified the most influential variables throughout the design process, highlighting aspect ratio in early design stage, the structure and insulation materials for walls in detailed design stages, and the roof title in construction design stages. The outcomes of this research can assist in understanding the importance of design variables in each design stage throughout the design process of a building.