Offsite Modular Construction Research Articles

A module layout design tool for off-site factory construction: Reactor Auxiliary balance of plant systems case study

There is significant interest in off-site modular factory construction for nuclear power. The IAEA defines Small Modular Reactors as “factory shop built and transported to site” and lists over 30 water cooled, 14 high temperature, 10 fast neutron, 10 molten salt, and 8 micro reactors in development worldwide. Off-site modular construction is a new development and offers more reliability in the construction and nuclear industries. A tool to help designers navigate the plethora of increased options and design challenges that modular design presents has therefore been identified as possibly increasing the efficiency and effectiveness of the design process, especially in the concept design phase. This study found that the method can create a starting point for design engineers to iterate and improve designs, significantly reduce design time in finding improved solutions, and improve performance and reduce costs associated with pipe length and network flows around the plant.

Transport, constructability, and economic advantages of SMR modularization

This paper presents an offsite modular construction approach, subject to transport constraints, for nuclear power plants. The modular construction principles underlying this work are generalizable across different reactor types; however, this paper focuses only on Small Modular Reactors (SMRs) that are of the Pressurized Water Reactor (PWR) type. Existing work on large nuclear reactor modularization is used to generate a module breakdown scheme for both small and large reactors and a module reconfiguration strategy is proposed that allows modules to fit within road transportable weight and dimension limits. Fully modularized SMRs can transport approximately 80% of their modules by road, compared to only 20% for large reactors. This has a significant effect on cost: a first-of-a-series, fully modular 300 MWe SMR can reduce overnight construction costs to $5470/kWe, a 45% reduction relative to its conventionally-built counterpart. This suggests that by using a standard design and radical modularization, SMRs could compete with current large reactor baseline construction costs of $6100/kWe. Standardization, another aspect of modular manufacturing best-practise, serves to remove repeat design costs and lowers nuclear construction costs by 15%. Additionally, SMRs can further reduce costs through shorter build schedules and production learning. These findings emphasize the importance of modularization for small reactor economics, highlighting the need for further research into the issues surrounding modularization, factory-centered offsite build, and supply chain strategy for small reactors.

A quantitative assessment of greenhouse gas (GHG) emissions from conventional and modular construction: A case of developing country

Building construction serves a vital purpose from a social and economic perspective by meeting the housing needs of society and contributing to the economic growth of a country. However, from an environmental perspective, this sector contributes negatively by releasing tons of greenhouse gas emissions (GHG) in the atmosphere, which consequently gives rise to other environmental hazards such as global warming and ozone depletion. The use of off-site modular construction practices in developed countries is increasing due to its environmental benefits over conventional cast-in-situ method. However, the environmental performance of a construction method may vary across various geographical regions, which is why environmental assessment of construction methods specific to a region is required. This study provides a calculation of GHG emissions in modular and conventional construction methods utilized in Pakistan, considering two single-family single-storey buildings with similar characteristics. The study also provides recommendations to homebuilders for the improvements in low-performance areas in both modular and conventional building methods. The results of the study show that modular building accounts for a total of 3449.73 kgCO2-equivalent GHG emissions whereas conventional building resulted in a total of 6501.91 kgCO2-equivalent GHG emissions. Modular building results in a reduction of 3052.19 kgCO2-equivalent GHG emissions (46.9%) as compared to a conventional site-built building. This implies that the modular construction method is a more environmentally viable option than conventional construction, which needs to be adopted on a large scale to reduce GHG emissions.

Global Academy, London: how offsite modular construction is reshaping education

The Global Academy in west London, UK, was the country’s first university technical college to be built using offsite modular construction techniques. Advanced offsite modular technology integrated with traditional site-based building solutions enabled the project to meet a challenging programme on a constrained plot. The college was built in just 12 months, providing a new state-of-the-art educational facility for 800 14–19-year-old broadcast and digital media students. It has a structural design life of 60 years and high levels of acoustic performance and energy efficiency. This paper reviews the methods used to design, engineer and build the college and the key role played by offsite modular construction.

Delivering offsite modular construction in the water sector: a Scottish case study

Offsite-manufactured modular water treatment plants can improve water quality and safety as well as deliver certainty and savings in time, costs, resources, logistics and emissions. This paper describes the collaborative design and delivery of a new 1·3 Ml/d Lochmaddy water treatment works for Scottish Water on the remote island of North Uist in the Outer Hebrides. By changing the treatment method to nanofiltration and using an offsite modular approach, the project team cut costs and programme by over a third. The 12 modules for the treatment building were designed, fabricated, assembled, tested and pre-commissioned in the factory before delivery to site, where they were installed in just 4 weeks.

Modularisation and offsite in engineering construction: an early decision-support tool

Modularisation and offsite manufacture are increasing in the engineering construction sector. Decision-support tools for determining a project’s suitability for offsite modular construction are currently limited or outdated, leading to decisions being based mainly around capital cost, experience or intuition. This paper reports on the development of a robust, empirically based decision-support tool for decision makers and clients. A mixed method methodology was conducted involving engineering construction clients, contractors, consultants and suppliers from all over Europe, after which the tool was developed, piloted and validated with practising engineers. It is the first globally applicable tool enabling informed and auditable decisions on using an offsite modular approach for project delivery.

Controlled heavy-haul traffic loading as a method to remediate liquefiable soft silts

Transporting of extremely large indivisible loads (10 000–30 000 t) is becoming increasingly popular to allow offsite modular construction of infrastructure for oil and gas, mining, and renewable energy projects in remote areas. Such exceptionally large transient loads could encounter unusual geohazards: there is a risk of metastable liquefaction when crossing soft alluvium, causing sudden failure, potential casualties, and severe production delays. Furthermore, temporary roads for these payloads are a large cost to such projects; conventionally designed earthworks and (or) ground improvement are often unaffordable or logistically impossible. This laboratory study indicates the fabric can be strengthened, and the hazard reduced, if the soil is subjected to careful repeated loading that rearranges the initially precarious fabric through gradual accumulation of plastic strains. A novel remediation technique for these temporary haul roads is proposed: managed deployment of increasingly heavy haul vehicles could result in staged fabric rearrangement that strengthens the soil to the point where it would be safe for the heavy vehicles to use it. In so doing, a more economic temporary haul road is open to operations (coupled with observation methods to ensure adequate performance throughout) and production activities are not overly disrupted.

Off-site Modular Construction as a Method of Improving Construction Quality and Safety

Off-site Modular Construction as a Method of Improving Construction Quality and Safety

Design automation of control panels for automated modular construction machines

Modern modular construction demands high quality, cost-effective, and efficient production of components. These requirements have led to the emergence of offsite construction manufacturing, which necessitates the use of automated machines. Compared to traditional onsite methods, offsite modular construction has a positive impact on quality, safety, cost, and productivity. Methodologies exist in the design of automated modular construction machines. This automation consists of not only the machines but also the supportive electrical and pneumatic systems, which, regardless of the design approaches used for automated machines, can be applied to the design of their associated systems. To avoid costly design changes, there is a clear need for a systematic and iterative design methodology at the conceptual design stage. For the control panel, the conceptual design method introduced in this paper facilitates the subsequent computer-aided design to be performed at the detailed design stage. Integrated function modeling, combined with axiomatic design and design structure matrix, constitutes the conceptual design approach for the control panel. In this work, linear time complex algorithm is developed for automating the layout of the electrical devices and wiring connections in order to facilitate computer-aided design implementation in the detailed design phase. Furthermore, the control panel guidelines and standards that constitute the prior knowledge of the design process are embedded in the algorithm.

AUTOMATION OF A STEEL WALL FRAMING ASSEMBLY

Modular construction has become increasingly popular in North America in recent years. In this emerging paradigm of building construction, building components are manufactured off site and then transported to the construction site for assembly. In Canada, automated modular steel structure fabrication is in high demand. Offsite manufacturing of steel wall frames for residential and commercial buildings provides timesaving and improvement of working conditions and morale that translates to improved productivity and safety performance. This paper demonstrates the feasibility of efficiently fabricating steel wall frames for offsite modular construction using automated assembly controlled by a Programmable Logic Controller (PLC) and connected in a cost-effective and efficient electrical installation and centralized communication by Fieldbus technology. In particular, this paper describes the control strategy used to automate a steel wall framing assembly that incorporates a PLC and Fieldbus technology.

Exploring the Benefits of Early Contractor Involvement (ECI) and the Mechanism for Automated 5D BIM Quantification Process in Offsite Modular Construction

The UK Construction Industry through its Government Construction Strategy has recently been mandated to implement Level 2 Building Information Modelling (BIM) on public sector projects. This move, along with other initiatives is key to driving a requirement for 25% cost reduction (establishing the most cost-effective means) on. Other key deliverables within the strategy include reduction in overall project time, early contractor involvement, improved sustainability and enhanced product quality. Collaboration and integrated project delivery is central to the level 2 implementation strategy yet the key protocols or standards relative to cost within BIM processes is not well defined. As offsite construction becomes more prolific within the UK construction sector, this construction approach coupled with BIM, particularly 5D automated quantification process, and early contractor involvement provides significant opportunities for the sector to meet government targets. Early contractor involvement is supported by both the industry and the successive Governments as a credible means to avoid and manage project risks, encourage innovation and value add, making cost and project time predictable, and improving outcomes. The contractor is seen as an expert in construction and could be counter intuitive to exclude such valuable expertise from the pre-construction phase especially with the BIM intent of äóÖbuild it twiceäó», once virtually and once physically. In particular when offsite construction is used, the contractoräó»s construction expertise should be leveraged for the virtual build in BIM-designed projects to ensure a fully streamlined process. Building in a layer of automated costing through 5D BIM will bring about a more robust method of quantification and can help to deliver the 25% reduction in overall cost of a project. Using a literature review and a case study, this paper will look into the benefits of Early Contractor Involvement (ECI) and the impact of 5D BIM on the offsite construction process.

3d/4d Visualization Framework for Modelling Off-Site Productivity of Modular Construction Housing

Construction, as the process of constructing a building, has diverse range of available software tools which have been developed to support modelling operations, tasks, and processes in the construction industry. 3D visualization as a modelling tool has been widely used to improve modular and off-site construction activities; it allows for seamless information sharing and collaboration among project stakeholders, and also provides opportunities for improvements suggested by the project team. This paper presents a framework for modelling the off-site modular construction of housing at the Kent Homes manufacturing facility through 3D/4D visualization. A case study is represented to illustrate the potential for production improvement.

Implementation of Prefabrication and Modular Offsite Construction using BIM and Lean Construction Techniques

The construction industry continues to experience productivity rates that lag behind other industries. Additionally, an increasingly competitive market and a decreasing skilled labor pool are challenging construction firms. Prefabrication and offsite modular construction techniques offer alternatives to traditional site-built construction methods that have the potential to provide improved productivity as well as other added benefits. Prefabrication methods, applied effectively, offer results that produce value to the project team. Such value includes improved productivity and efficiency in construction operations, reduced project costs, reduced schedule durations, and improved safety, increased levels of quality and improved sustainability and waste reduction. Currently the implementation of prefabrication and offsite construction techniques on the construction project remains subjective and unstandardized. The aim of this research is to develop a framework that will assist the project team to make decisions regarding the use of prefabrication and modular construction based on factors that have proven to be the most successful in implementing modern methods of construction. The concentration is on emphasizing the use of Building Information Modeling and Lean Construction methods as catalysts to maximize the effectiveness of the use of modular offsite construction. This research is primarily toward the use of prefabrication and modular construction methods for vertical construction and should prove valuable for all project players including Owners, Designers and Constructors. The development of this framework utilizes information compiled through interviews and case studies to develop a proposed framework for implementing prefabrication and off-site modular construction techniques at the project level. The framework will be validated in the future using a Delphi survey to qualitatively generate quantified data on the best methods to implement prefabrication and offsite construction techniques.