Modular construction is a construction technique which involves the prefabrication of 2D panels or 3D volumetric structures in off-site factories and transportation to construction sites for assembly. This process has the potential to be superior to traditional building in terms of both time and costs, with claimed time savings of between 20 and 50 percent faster than traditional building techniques. It is estimated that by 2030, modular construction could deliver US$22 billion in annual cost savings for the US and European construction industry, helping fill the US$1.6 trillion productivity gap. The current need for standardized, repeatable 3D volumetric housing pre-fabricated units and designs for student accommodations, affordable housing and hotels is driving demand for modular construction.
Advantages In a 2018 Practice Note, the NEC states that the benefits obtained from offsite construction mainly relate to the creation of components in a factory setting, protected from the weather and using manufacturing techniques such as assembly lines with dedicated and specialist equipment. Through the use of appropriate technology, modular construction can:
increase the speed of construction by increasing the speed of manufacture of the component parts, reduce waste, increase economies of scale, improve quality leading to reduction in the whole life costs of assets reduce environmental impact such as dust and noise and reduce accidents and ill health by reducing the amount of construction work taking place at site
Disadvantages In contrast to the benefits mentioned earlier, modular construction presents two significant obstacles:
Logistical challenges: The transportation of completed modules to the construction site demands meticulous organization and synchronization, often incurring substantial costs. Constraints on size: The manufacturing and transportation procedures may place limitations on the dimensions of individual modular components. This can impact the room sizes in the building, potentially influencing the overall architectural design.
Time Modular construction has consistently been at least 20 percent faster than traditional on-site builds. Currently, the design process of modular construction projects tends to take longer than that of traditional building. This is because modular construction is a fairly new technology and not many architects and engineers have experience working with it. In fewer words, the industry has not yet learned how to work this way. It is expected of design firms to develop module libraries which would assist in the automation of this process. These modules libraries would hold various pre-designed 2D panels and 3D structures which would be digitally assembled to create standardized structures. The foundations of a structure are a crucial part of its rigidity. The magnitude and complexity of such will vary depending on the size, and overall weight of the structure. Therefore, the weight difference of a traditionally built house and a prefabricated structure will mean that foundations needed will be smaller and faster to build. Off-site manufacturing is the pinnacle of modular construction. The ability to coordinate and repeat activities in a factory along with the increased help of automation result in largely faster manufacturing times than those of on-site building. A large time saver is the ability to parallelly work on the foundation of a structure and the manufacturing of the structure itself. This would be impossible with traditional construction. The on-site construction is radically simplified. The assembly of pre-fabricated components is as simple as assembling the 3D modules, and connecting the services to main site connections. A team of five workers can assemble up to six 3D modules, or the equivalent of 270 square meters of finished floor area, in a single work day.
Production algorithms Since the technology required to manufacture the components of modular construction, the prefabricated parts of modular buildings are carried out by modular factories. To optimize time, modular factories consider the specifications and resources of the project and adapt a scheduling algorithm to fulfill the needs of this unique project. However, current scheduling methods assume the quantity of resources will never reach zero, therefore representing an unrealistic work cycle. A modular factory handling a single project at any given point is rare, and would produce low returns. Hyun and Lee's research propose a Genetic Algorithm (GA) scheduling model which takes into consideration various project's characteristics and shares resources. The production sequence of this algorithm would be largely affected by which modules need to be transported to which site and the dates they should arrive. After considering the variables of production, transportation and on-site assembly the objective function is: m i n Σ ( S ) , … S = S i + P i − E i {\displaystyle min\Sigma (S),\ldots S=S_{i}+P_{i}-E_{i}} Where Si is the number of stocked units per day, Pi is the number of units per day and Ei is number of units installed per day. Production algorithms are continuously being developed to further accelerate the production of modular construction buildings, enlarging the time saving gap with traditional construction methods.
Cost Modular construction can yield up to 20 percent of the total project cost in savings. However, there is also a risk of it increasing the cost by 10 percent. This occurs when the savings in the labor area of construction are outweighed by the increase in costs of the logistics area and materials. The pre-fabrication of components used in modular construction have a higher logistics cost than traditional building. Since the panels or 3D structures have to be manufactured in a factory and transported to the construction site, new variables which alter the flow of construction are presented.
… excerpt ends here. Continue reading the full article.
