Exhaustive Exploration of Modular Design Options to Inform Decision Making Mohammed Mekawy1, Frank Petzold2 1,2Technical University of Munich [email protected] [email protected] Europe is facing an increasing demand for new construction, which is pushing the industry away from traditional construction technology towards prefabrication and Mass-Customization. However, prefabrication-based construction requires a more efficient, better informed decision making process due to the increased difficulty of on-site variations. Furthermore, the lack of means to navigate the whole spectrum of solutions for a given design problem using traditional tools, and the absence of the manufacturer's input in the early phases of the project can present significant challenges for the efficiency of the design and construction process. As a way to face these challenges, this paper presents an approach, realized as an Autodesk Dynamo-for-Revit package called Box Module Generator (BMG), which enables the exhaustive generation of configurations for a given building based on a construction scheme that utilizes Box Prefabricates. The output can be sorted, dissected and explored by users in various ways and the building geometry can be generated automatically in a Building Information Modeling environment. This makes it possible for the projects' stakeholders to browse thousands of potential design alternatives, which would otherwise be very hard to explore manually, or using traditional parametric modelers. Keywords: Prefabrication, Box Prefabricates, Design Tools, Design Automation, Building Information Modeling, Dynamo INTRODUCTION turies, especially after World War II, to cover the post- Attempts at prefabricating building modules to pro- war housing needs in Europe (Huang et al., 2006). vide large amounts of well-constructed spaces date The need for high quality, speedy construction is still back at least to the Crimean war in 1854, when Isam- ubiquitous. Europe in general, and Germany with its bard Kingdom Brunel designed and built a 1,000 very buoyant labor market in particular, are facing a patient hospital in Renkioi using prefabricated tim- fast growing need for new construction. For exam- ber units that were shipped to be assembled on-site ple, to accommodate the increase in inhabitants in (Gibb, 1999). The trend of using prefabrication in Munich between 2011 and 2016 alone, 55,000 homes construction to minimize time and waste continued are needed simply to cover the gap in the supply of to rise during the eighteenth and nineteenth cen- housing units (Möbert, 2017). This highly challeng- FABRICATION - MANUFACTURING - Volume 2 - eCAADe 35 | 107 ing environment demands more efficiency in design rooms or a group of rooms (Lewicki, 1966). These and construction, giving rise to the idea of Mass Cus- box modules are suitable for a lot of building types, tomization. can be repeated by stacking, and can be 95% deco- rated and fitted with the necessary equipment in fac- tory, reducing the work on-site to the assembly of the units and connecting them to services (Knaack, Figure 1 2012). This approach comes with a multitude of ben- Box modules in the efits: consistent quality because units are manufac- Pillerseetal social tured under factory conditions, Just-in-Time deliv- center in ery to construction site to decrease waste and pre- Fieberbrunn, vent material theft on-site, and time savings up to Austria assembled 50% in projects’ schedules (Gibb, 1999). An exam- on-site after being ple of such an approach is shown in Figure 1, where manufactured in 78 box modules acting as rooms for senior citizens factory (Kaufmann were installed in a social center in Fieberbrunn, Aus- Bausysteme, 2016). tria, complete with flooring, windows, doors, bath equipment and furnishings. Box Prefabricates can be constructed from steel, wood, or concrete; they can also be self-supported or installed on a supporting Mass Customization corresponds to technologies structure (Staib et al., 2008). They can thus be mass- and systems that are used to deliver goods and ser- customized to meet the individual needs of each vices in order to meet individual needs with enough project with different sizes, finishes, fittings, and with variety and customization and with mass production closed or open sides to fit both open plan and closed efficiency (Piroozfar and Piller, 2013). One of the rooms schemes (See Figure 2). key strategies for Mass Customization is modulariza- tion, whereby building designs are based on mod- ular components and subsystems that are prefabri- Figure 2 cated in parallel in a factory and afterwards assem- Different bled on the construction site to satisfy the individ- configurations from ual requirements for each building design (Huang et the box modules: a) al., 2006). Mass-Customization and prefabrication of- Closed from all fer significant advantages to the construction indus- sides b) Open from try including time saving in construction schedules, But the nature of design for prefabrication-based the long sides c) lower construction cost, tighter quality control, less construction differs from that of the traditional con- Open from the material waste, better sustainability, enhanced occu- struction because of the increased difficulty of on- narrow sides pational health and safety, lower manpower require- site variations to the design when using prefabri- ments, and a safer working environment (Tam et al., cated components (Maxwell, 2015). That means that 2007) (Rathnapala, 2009) (McGraw Hill Contruction, programming and design phases have to be more 2011). robust and better informed than in traditional con- One of the approaches to Mass Customization struction to minimize the possibility of last-minute and prefabrication is ”Box Prefabricates”. Building design changes. Furthermore, designers do not think designs that can afford a high level of modulariza- about spaces or modules only in a three-dimensional tion are standardized into a group of box modules, paradigm. In addition to the length, width, and which are large space prefabricates enclosing whole height of a space or a module, designers may also 108 | eCAADe 35 - FABRICATION - MANUFACTURING - Volume 2 Figure 3 consider orientation, cost, number of floors, and nat- The general ural lighting, among a group of parameters (n). De- framework of the signers have to navigate the full extent of varieties proposed tool of these n-dimensional spaces in order to make well- informed design decisions, a process that could be very daunting and labor intensive. Even in ordinary design problems, the architect may contemplate very few solutions like few needles in the haystack of all the configurations satisfying the boundary condi- tions of the design problem (Galle, 1981). While us- ing geometric parametric modelers can help design- ers, explore multiple design parameters more quickly and efficiently, they do not possess the ability to ex- plore the entire set of possible solutions, nor do they offer the rich data environment enabled by Building Information Modeling (BIM) platforms. The problem BACKGROUND can be further complicated by the lack of interac- Related work tion with prefabrication experts early on the design Retik and Warszawski (1994) presented a knowledge- project, leading to significant flows in project plan- based system that encapsulates prefabrication ex- ning, misinformed design decisions and unnecessary pertise for the automated detailed design of prefabri- rework. cated buildings. This system receives the preliminary By providing a platform that can generate an architectural design and then produces solutions for exhaustive list of all possible design configurations partitioning the building into modular components. and the outcomes of these configurations in a Huang and Krawczyk (2007) proposed a web-based rich BIM environment, stakeholders can make more design system that can generate design options for informed decisions with regard to prefabrication- modular houses based on the client’s needs, cap- based projects, and easily utilize the BIM models to tured via an online questionnaire. Diez et al. (2007) any (n) number of analyses necessary for a given presented an automatic modular construction soft- project. The intent of the research summarized here ware environment ”AUTMOD3” that offers two meth- is to provide a platform that enables the production ods of modular design; the architects can input ar- of this exhaustive list for a given project in a modular chitectural plans that can be processed to obtain construction scheme, with the scope being limited to the modules needed for a house design, or they can Box Prefabricates. The range of input parameters in- make the design from scratch using a catalogue of 3D tegrates the input from prefabricators, owners, and parametric modules. El-Zanfaly (2009) built a user in- the architects. The visual and numerical output can terface to produce alternatives for modular housing be sorted, filtered, and viewed in different ways that arrangements. Through the interface, the user can serve as a basis for the decision making process in the vary the design parameters and specify a number of early design stages and design brief. The aim of this alternatives. The system will then produce 3D alter- process is not to automate the design of the entire natives based on stochastic search. Kwiecinski et al. building with all details. Instead it serves as a way for (2016) proposed a design method based on shape stakeholders to rapidly assess hundreds or thousands grammars, focusing