Volumetric modular construction has gained considerable momentum over the past 3-5 years in the UK due to its positive impact on cost, programme, quality and safety. Darren Richards, Managing Director of leading offsite construction consultancy, Cogent Consulting illustrates how best to optimise it’s use.
The advantages of volumetric modular construction have been known for decades and yet critical success factors and enablers for optimal industrial modularisation, at a scale which generates genuine economies of scale, have only recently been realised. The critical success factors for ‘modularisation’ have recently highlighted the need for engineering, procurement and construction project delivery systems to be developed to support optimal use of volumetric modular technology.
The percentage of offsite manufacturing for volumetric modular construction ranges between 60 and 70%, compared with 30 to 50% for hybrid construction and 15 to 20% for panelised construction. This accounts for 50 to 60% construction time reduction for volumetric modular construction compared with 30 to 40% with hybrid construction and 20 to 30% for panelised construction, so the onsite gains to be made are significant but only if the technology is considered correctly and planned for at the start of the project.
Module selection can also often be significantly influenced by transportation dimensions and shipping distances between the manufacturing facility and the construction site. In addition, module connection details and quantities, installation and crane costing rates relative to the planned speed of installation, specific site logistics constraints, foundation/transfer deck and service core requirements plus the volume of concrete required – all need to be viewed holistically with module configuration for optimised design efficiency to be achieved.
Systematic Processes for Modularity
There needs to be a systematic process to quantify the degree of modularity in construction projects, quantifying the key parameters and allowing volumetric modular techniques to compete with hybrid solutions, where many more architects and contractors are using hybrid techniques to eliminate some of the dimensional limitations that volumetric modular techniques currently face.
New methodologies need to address the lack of knowledge by architects about the limitations of the manufacturing process of modules, as well as considering a set of practical constraints and factors that affect module configuration such as onsite connection limitations, transportation and weight limitations and crane cost limitation.
The needs of the customer will have been identified based on building geometrical shapes – arranged in a manner that maximises the quality and function relationship in the design phase. However, standardised products (modules) significantly impact the design of buildings, especially when the design needs to be adapted to suit the customer requirements – such adaptation causes waste, inefficiency and possible quality problems within the manufacturing process. The demand for customisation compels the manufacturing industry to develop new methods for adaptation of their mass production to satisfy the individual needs of customers.
Methods have been developed to standardise the production and configuration processes by conducting functional requirement analysis to identify design parameters for modular construction of buildings. These methods typically constrain the modularisation of the project using four key parameters:
• Customer view that controls the modular design according to customer requirements
• Engineering view that constrains the module design according to deflection, strength, wind loads, fire, acoustic and building regulations
• Production view that identifies product dimensions and transportation constraints according to factory regulations and capacity
• Site view for assembly constraints on site according to site layout/plans.
Further perspectives - 'rules' and constraints of modular buildings or product platforms – can be integrated in to family of architectural CAD applications using the likes of Revit structures, where key features of steel, concrete or timber volumetric modules can be integrated in a ‘modular toolkit’, thereby providing the basic rules of the game.
Modular Methodology
If volumetric modular techniques are to gain market share more rapidly in order to create the market climate for further manufacturing investment then the technology needs to be more intelligently applied.
A recent publication from Canada via Concordia University in Montreal and Alberta University has put forward a structured methodology that uses five indices which accounts for: connection of modules onsite (CI), transportation of fabricated modules to the construction jobsite (TDI and TSDI), crane operating condition and related cost (CCPI) and project concrete foundation (CVI). These five indices are integrated in to one indicator (MSI) measuring the relative suitability of competing modular designs. The full paper provides some interesting worked examples and can be downloaded via: http://dx.doi.org/10.1016/j.autcon.2017.03.008
The developed modular suitability index (MSI) methodology cited above is one proposed method of providing a quantitative indicator for the suitability of modular design configuration in building construction. It integrates several typical indices and it has concluded that reducing the number of module connections shall be cost efficient if transportation and weight limitations are satisfied. The MSI can be reduced by developing new cost-efficient connections between modules that require lower installation and maintenance costs. Acquiring experienced personnel for transportation and crane selection, location, lifting and positioning enables volumetric modular construction companies to deliver construction projects efficiently. Whilst, to the experience user of volumetric modular technology much of this will seem obvious, the MSI methodology does at least provide a starting framework from which the uninitiated can begin.
Design for Modular Assembly – DfMA 2.0
The type of research associated with the MSI methodology begins to expand the thinking around Design for Manufacture and Assembly (DfMA) by taking into account a wider range of parameters that need to be considered when specifying volumetric modular technology. Perhaps it takes us in to the realms of hi-jacking DfMA and in this context moving the dialogue towards design for modular assembly? Perhaps this is something that the UK volumetric modular industry should consider championing?
Whatever the terminology, these new systemised techniques need to be ‘industrialised’ and embraced by the wider volumetric modular manufacturing base in the UK or a methodology needs to be created by the collaboration of relevant trade associations, most notably the Modular and Portable Building Association (MPBA), perhaps in conjunction with the Steel Construction Institute, the Structural Timber Association and the Concrete Centre?
There is a definite need for an agreed protocol to help standardise procurement and specification to deliver the optimum selection for efficient modular design and to standardise the module configuration selection process.
The development of new methodologies to support the identification and selection of near optimum module configurations that account for project constraints is essential if the perceived barriers to application are to be taken down. It will assist developers and project stakeholders to deliver projects not only with accelerated schedules but also with cost reduction – perhaps creating the panacea of a more cost-effective method of construction than traditional construction methods on a more consistent basis?
If you would like to get involved in developing new specification and procurement methodologies for the use of volumetric modular construction techniques then please get in touch. Cogent Consulting are currently working to instigate the collaborative development of these methodologies and are seeking industry partners in this regard.
For contact details and a more detailed perspective on the work that Cogent Consulting undertake please visit: www.cogent-consulting.co.uk
