How Lean Construction Benefits from DfMA

Construction industry buzzwords ‘DfMA’ and ‘lean construction’ have much to offer each other. Design for Manufacture and Assembly (DfMA), with the combined features of Design for Manufacture and Design for Assembly, employs the benefits of prefabricated construction modelling and design to benefit a growing move to incorporate lean construction concepts in building construction. So, looking at Design for Manufacture, the more important features are: Comprehending processes, capabilities and cost factors Choosing materials Estimating costs Modifying designs and models Important features of Design for Assembly include the following: Understanding when to move a part independently Knowing which parts need different materials or need to be separate Calculating part limitations for transport Knowing the assembly time for each part What DfMA does in essence can be summarised as follows: Deciding the best way to manufacture parts and assemble them off site and transport them on site Uses prefabrication of components and modules Uses a process for the entire design team Used for customised buildings or mass production Now, what are the general benefits of DfMA? Design that enables efficient construction Reduced costs On-time delivery of projects Improved quality, safety and easier maintenance of the building Reduced trades work on site Reduced impact on the public When DfMA is used for modular design, the following benefits may result: Reduced costs, interfaces, components, schedules, on-site trades Improved tolerance, processes which can be repeated Detailed specifications and orientations Easy access for maintenance, refurbishment and renewal Now, how does all this tie in with ‘lean construction’? Well, the philosophy of lean construction maintains that processes much be continuously improved or updated and waste should be eliminated as much as possible. Combining the features of DfMA with the principles of lean construction results in several gains, such as: Deciding and working around constraints Analysing the build sequence Determining where to manufacture off site Integrating elements to on-site material Eliminating wasteful components Improving collaboration between trades Lean construction methods try to maximise value for customers while minimising waste. In the construction industry, where budgets, on-time deliveries and safety are crucial to a project’s success, the lean methodology seems to be a desirable option. For lean construction, DfMA considers design before manufacturing. The lean approach requires certain processes that prefabrication and Building Information Modelling (BIM), especially prefabricated construction BIM, can help with, such as: A. Identifying Value for the Customer Establishing and earning the customers’ trust early in the planning and design stage is important. In lean construction, owners, architects, engineers, general contractors, trade contractors and suppliers must work together to fulfil client objectives, provide advice and project realistic expectations. B. Defining the Value Clearly communicate the processes required to deliver this value. The requisite labour, data, infrastructure and materials for each part of the process are specified, and processes that do not add value are eliminated. Prefabricated construction modelling supplies an accurate view of the benefits of prefabrication of components or modules for all the project stakeholders. C. Eliminating Waste Whenever Possible To practice lean construction, this is a key list of wasteful hurdles that must be eliminated: Defective process – an incorrect process that results in rework, wastes materials and time Overproduction – when a task ends earlier than it’s supposed to/before the next task can be initiated Waiting – when workers must wait for undelivered materials or prior tasks have not been completed Not Utilising Talent – when workers are incorrectly matched to a job, wasting their expertise Unscheduled transport – when data, materials or workers are moved to a site before they are required Excessive inventory – the accumulation of materials not immediately needed tie up budgets, need storage space and may degrade while unused Over-processing – adding features or activities that have no value for the client So, where has DfMA been used to help the lean construction methodology? A. In Hospitals Patient room floor plans can be designed for limited types using 3D CAD modelling services that feature prefabricated bathroom pods with minimal plumbing deviations. Bathroom pods have been constructed in 80 work hours, and in one case, 26 workers completed 14 pods at the same time. Prefabrication, especially for mechanical, plumbing and drywall work, mechanical racks, bathroom pods and zone valve boxes for medical gas can be manufactured in a factory and transported to the site. In one day, a rack can be created with dimensions 18ft x 8ft x 4ft. Employing the lean approach, the Unistrut racking can be tweaked to stack three racks, saving the number of crane picks. Working in the warehouse can result in reducing on-site hustling for space and time between different trade workers, reducing the difficulty of worker commute to a heavily congested work site and enabling night deliveries. In a factory setting, it becomes easier to install MEP (mechanical, electrical, plumbing) equipment than installing it on site, and welding executed in a controlled environment results in greater worker safety. B. For Rapid Deployment Data Centers (RDDC) Modular construction can be used with lean design principles to reduce the amount of materials used and create facilities. Most components can be used interchangeably by using prefabricated assemblies. Standard designs for component assemblies result in the manufacture of unit data centres. Two prefabrication concepts that support the creation of RDDCs are: Chassis Assembly A chassis of pre-assembled steel frames (12ft x 40ft) carry data centre components – cable trays, power busways, containment panels, lighting, which are fixed in a factory. The chassis are transported to the site and mounted on steel columns, connecting them end to end. Server racks are placed under the connected chassis. Flat-pack Assembly Walls and ceiling panels are packed into standard eight-foot modules, which are transported to the site. Metal studs and units of pre-assembled containment panels, which are self-supporting, are erected on the site. A metal deck in the ceiling panels span the cold aisle and racks, carrying the loads of the trays, power bus and light fixtures with a hanger clip for threaded rods. C. To Customise Home Layouts Individual specifications can be executed in a factory setting. A two-storey home can be created in a factory, with a simple layout, high ceilings, doors Entire floors can be created at the factory and then delivered to the site for stacking, or certain components, such as 2D facade envelopes, can be manufactured at the factory and then assembled on site as a 3D structure. In addition to bathroom pods, RDDCs and customised homes, the DfMA methodology serves lean construction principles with environmentally friendly practices. For instance, prefabricated buildings typically utilize efficient windows, solar panels, energy-efficient water heaters and geothermal systems and are also easier to maintain, saving energy on several fronts. Furthering the green and lean concepts, recycled materials can be used to construct modular components, using fewer natural resources. Construction time periods are reduced, resulting in energy efficiency. In fact, studies have shown that, compared to the usual construction site, using prefabrication may result in the reduction of energy consumption by 67%. Using prefabrication within the lean construction environment has been shown to result in time and cost savings, reduction of errors and improved safety. It is likely that the DfMA approach will produce energy efficiency, flexibility and building endurance, hallmarks of lean construction, for some time in the future. The calculations, ordering to precise specifications and accurate design required in the DfMA process to reduce carbon footprints require the experience, expertise (delivering prefabricated construction modelling) and special skills of qualified technical designers, increasingly found overseas, especially in countries such as India. With the right cost-effective design support, including the delivery of precise modular construction drawings, for lean construction using DfMA, projects can be delivered on time, within budget and to a high level of value for the customer.