Developing optimization models for promoting prefabricated construction

Abstract

Prefabrication has been recognized as a highly promising construction method to fulfill the growing expectations of both government and industry in terms of enhancing the productivity, quality, and sustainability of construction activities. Despite the numerous benefits of prefabricated construction (e.g., less greenhouse gas emission, lower energy consumption, reduced on-site labor demand, and enhanced construction efficiency), the adoption of prefabrication in real-life building projects remains at a low level owing to cost-, technology-, knowledge-, and policy-related factors. The greatest deterrent to the promotion of prefabrication, as widely perceived by academia and industry, is high costs, which discourage practitioners from embracing this innovative technology. Although governments in different countries and regions (including Singapore, China, and Hong Kong) have implemented incentive policies to encourage the use of prefabrication, and the global construction industry has released guidelines to provide suggestions on the management of prefabricated components (PCs), current measures and recommendations are proposed mainly based on practical experience and industry expertise. To facilitate the sustainable development of the construction industry, it is crucial to develop more scientific approaches to design effective countermeasures that can help practitioners overcome various cost-related challenges of implementing prefabrication. Motivated by the practical needs of both governments and industry, this study aims to increase the adoption of prefabrication in the construction industry and ease the restrictions on PC and module transportation. This is achieved through the mathematical optimization of several theoretically interesting and practically important decision problems related to prefabrication adoption. The objectives of the study are to (i) propose effective government subsidy schemes to offset the high costs incurred by the use of PCs and modules; (ii) develop logistics plans according to the characteristics of different types of prefabricated products to reduce transportation costs; (iii) validate the effectiveness and applicability of the proposed methodology in various countries and regions using case studies of Hong Kong; and (iv) propose policy recommendations and managerial insights for both government and industry to enhance the sustainability of the construction sector. Practical decision problems are formulated into mathematical models with high precision, clarity, and brevity, and then efficiently solved by high-quality algorithms developed in this study. Data used in experimental validation mainly originate from official documents issued by government departments and the Construction Industry Council of Hong Kong. In this study, useful mathematical optimization tools are developed that can help governments formulate an effective prefabrication subsidy scheme and help practitioners generate optimal PC stacking and transportation plans. Results show that the proposed methodology provides a framework for automatic calculations and enables the derivation of optimal solutions in real-world settings within seconds. Moreover, the findings of this study indicate the following: (i) Full consideration of the tri-level interactive relations between governments, manufacturers, and contractors is crucial for designing effective prefabrication subsidy policies. (ii) High land cost is a huge obstacle to the establishment of local prefabrication factories, which further hinders the promotion of prefabrication. (iii) Formulating panel and slab stacking problems into bi-objective models can help practitioners balance trade-offs between two objectives, resulting in more satisfactory PC stacking plans. (iv) Compared with the just-in-time strategy, the reservation of an appropriate on-site storage area can lower the module transportation costs by substantially reducing the number of module shipment days. This study makes theoretical and practical contributions to the wide promotion of prefabrication. It represents an interdisciplinary investigation that innovatively integrates knowledge from construction management, policy design, and transport planning. A theoretical decision framework that incorporates a wide range of factors and objectives into the formulation of optimization problems is proposed, and efficient solution methods are developed for problem-solving. Moreover, this study can enhance the collaboration between governments and various stakeholders for the sustainable development of the construction industry. The Hong Kong case studies demonstrate that the developed tools can be generalized and applied to various real-world scenarios, particularly those that cannot be adequately addressed by “rule of thumb” approaches owing to significant deviations from optimal solutions. Overall, this study lays the groundwork for adopting mathematical optimization methodology in construction and engineering management, aiming to achieve maximum levels of economic and environmental performance in the construction sector.