Economic sustainability benchmarking of modular homes: A life cycle thinking approach

Sustainable built environment has been of interest to many stakeholders in the recent years. However, life cycle economic performance as one of the key dimensions of sustainability has not been sufficiently investigated for buildings constructed using off-site construction methods such as modular construction. This research has proposed a framework to benchmark the life cycle economic sustainability of single-family modular homes. First, suitable economic performance criteria were selected and suitable measurable economic performance indicators were developed under each criterion. A performance level function was established for each indicator by which all indicators can be calculated and presented by a normalized performance level that enables combining quantitative and qualitative indicators. Subsequently, a multi-criteria decision analysis-based methodology was employed to develop a set of economic sustainability indices at the criteria level and also at the overall economic sustainability performance level. To compare and contrast the developed indices of a given modular building with the performance of similar conventional buildings, suitable performance benchmarks scales were established using the data of the historical economic performances of conventional homes. To examine the application of the proposed framework, two case study modular homes in British Columbia, Canada were analyzed. The results showed that both benchmarking homes performed 'Excellent' with respect to the overall economic sustainability. However, improvements are required to enhance the economic performance with respect to a number of criteria. The proposed framework can assist the construction decision makers, developers, and contractors with making informed decisions on the selection of the construction method. Furthermore, it can be used to address the underperforming areas over the life cycle of a modular building, even if the decision on the construction method has already been made.