Benefit evaluation for off‐site production in construction

Abstract

Evaluating to what extent a component or building system should be produced offsite is inadequate within the industry. The potential benefits of off-site production (OSP) are commonly cited when justifying an OSP approach, yet holistic and methodical assessments of the applicability and overall benefit of these solutions, to a particular project, have been found to be deficient. Common methods of evaluation simply take material, labour and transportation costs into account when comparing various options, often disregarding other cost-related items such as site facilities, crane use and rectification of works. These cost factors are usually buried within the nebulous preliminaries figure, with little reference to the building approach taken.Further, softer issues such as health and safety, effects on management and process benefits are either implicit or disregarded within these comparison exercises. Yet it is demonstrated that these issues are some of the most significant benefits of OSP. A series of case studies demonstrated that evaluation focus is almost solely on direct material and labour costs of components, without explicit regard for the wider cost or soft issue implications of OSP on a project. The paper argues that until evaluation is more holistic and value-based rather than cost-based, OSP uptake in construction will be slow. (204 words)

Maintenance cost implications of utilizing bathroom modules manufactured offsite

“…Some argue that the cost premium of specifying factory-fitted bathroom pods can even rise up to 30% compared with traditional bathroom fit-outs (see Waterman, 2006). To counter this view, research at Loughborough University (Blismas et al, 2006) has established that the main reason that the first costs of offsite solutions are often considered to be more expensive is that the comparison is not sensitive enough to the real outturn costs encountered on real projects. The decision support tool IMMPREST (www.IMMPREST.com) has been developed to provide a means for fair and accurate comparison of real value between offsite and on-site options (Blismas et al, 2005).…”

Establishing and Weighting Decision Criteria for Building System Selection in Housing Construction

“…Pasquire and Gibb (2002) reported that decisions to use offsite were largely based on anecdotal evidence rather than rigorous data as no formal measurement procedures or strategies were available. Blismas et al (2006) presented further evidence demonstrating that decisions to compare traditional and offsite technological solutions for construction in general were largely based on material, labor and transportation costs, whilst other cost-related items such as site facilities, crane use and rectification of works were disregarded or buried within the nebulous preliminary cost items, and softer issues such as health & safety, effects on management and process benefits were either implicit or disregarded. The industry, as a whole, still sees a fragmented cost-driven, rather than systematic value-based, decision culture prevailing in construction technology evaluation and selection practice.…”

“…This significance was highlighted in a recent survey of large UK housebuilders (Pan et al 2008) which reveals that the housebuilders assessed the potential for offsite-MMC applications against a wide range of factors including technical requirements, cost, time, site integration and logistical concerns, customer choice options, sales impacts, mortgage issues, and site constraints. Blismas et al (2006) suggested that a wider account of value-based measures including quality, health, safety, sustainability, and logistics as the means of broadening the comparative exercise from the one-dimensional cost basis to a multi-dimensional valuebased system. However, decision criteria derived on a value-laden basis have relative and context-specific features.…”

“…At the industry level, examples of important contexts included the annual targets of performance improvement in construction recommended by Egan (1998), the KPIs for new-build homes established by Constructing Excellence (2004), the drivers for and constraints to standardization and preassembly provided by Gibb and Pendlebury (2005), and the drivers and barriers to the use of offsite-MMC identified from leading housebuilders (Pan et al 2007). The performance indicators for assessing MMC suggested by NAO (2007) and the benefit evaluation framework for offsite production presented by Blismas et al (2006) also helped clarify the industry context. At the organizational level, the housebuilder considered a variety of criteria in order to satisfy their customers and elicit long-term profitability, which were reflected in their corporate policy and company documents such as the 'Guide for Design' (an internal design management tool) and the 'Environmental, Social and Ethics Review'.…”

Modular vs Conventional Construction: A Multi-Criteria Framework Approach

“…Having said that, plenty of the research conducted indicates that a controlled environment, such as the one presented in modular construction methods, where components are manufactured off-site in a continuous flow process, allows a lot of benefits to be achieved. These advantages can be realised in terms of productivity, safety and environmental performance [4], [12].…”