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.

Current State of Using Prefabricated Construction in Australia

“…The benefits related to the environment include less emissions, energy savings, reducing on-site construction waste, reducing the use of materials, improving waste recyclability and reducing disruption to neighbourhoods. Compared with the traditional construction method, prefabrication has significant environmental benefits throughout a project's lifecycle, including the reduction of greenhouse gas emissions [43], reduction of on-site construction waste [18] and reduction of material usage [27]. These reductions can enhance public health and can combat climate change, which is the fundamental goal suggested by the International Energy Agency (IEA) [63,64].…”

“…Based on the literature review on the benefits and challenges of implementing prefabricated construction, the most commonly applied research methods in these previous studies were case studies, literature reviews, interviews and surveys. Case studies were applied to measure the benefits and challenges of using prefabrication quantitatively [6,43]. Literature reviews were generally applied to identify research gaps on this topic, to identify the benefits and challenges of prefabrication qualitatively and to identify solutions for tackling these challenges [69,102].…”

General contractors’ experience using off-site structural framing systems

“…Fewer still have performed a case study that draws from the expertise of both the manufacturer and the builder. Benson and Rankin (2016) appealed to the construction community to perform more study comparing traditional building methods to modular, or manufactured construction methods. Kamali and Hewage (2016) stated that the US modular construction industry accounted for less than 1% of the total new multi-family houses between 2000 and 2014.…”