Measuring the Sustainable Benefits of Modular and Offsite Construction Delivery Techniques Against Conventional On-Site Construction

Abstract

It is well known that the use of modular and offsite construction (MOC) techniques for project delivery can yield significant economic, environmental, and social benefits throughout a projectäó»s lifetime. Despite these benefits highlighted by the MOC community, there exists a need to objectively measure the sustainable benefits and to integrate them in a comprehensive framework to compare delivery alternatives. The Sustainable Efficiency (SE) model is presented and used to compare the construction of a 2-storey hotel using two delivery methods: i) a conventional onsite construction (COC); and ii) modular and offsite construction (MOC). Sustainable criteria identified in the model originate from ISOäó»s 21929-2 äóìFramework for sustainability indicator for civil engineering worksäó�. These criteria are used to encompass the entire life-cycle of the project, from production and extraction of materials, through construction, operations and maintenance, to the end-of-life or decommissioning stage. MOC presents a significant amount of benefits throughout the entire life-cycle of the project and the SE model presented highlights and takes these benefits into account. Recognizing these benefits can help build the business case for MOC, going past the prescriptive, lowest initial cost, and onsite construction delivery that is widely used in the Canadian construction industry today. Allowing for both the quantitative and qualitative benefits to be included in an objective and metric-based model can address the challenge of making changes to conventional procurement methods, and will strengthen and promote the use of MOC in the construction industry. It was found that, through the use of MOC, the hotel obtained a positive 16.8% sustainable efficiency score over a conventional stick build method. Significant benefits were a result of reduced greenhouse gas emissions, non-renewable energy use, waste production, and worker health and safety. The single disadvantage determined was the social criteria äóìJob Creationäó� where there was a reduced quantity of worker hours required to complete the project.