Methodology for Digital Design and Additive Manufacturing of High Performance Building Façade Segment Optimized to Environmental Constraints AND Impact of Material Characteristics on Construction and Lifecycle Performance of Buildings

Project Team

M. Fischer, S. Billington, V. Bazjanac, N. Mrazovic

Research Update (Summer 2016)

The research has focused on formalizing an assessment framework to evaluate additive manufacturing (AM) vs. conventional manufacturing (CM) methods for building components. This assessment framework is based on lessons learned from two life cycle assessment (LCA) studies of a curtain wall window frame and a bracket used in curtain wall construction carried out with data from Permasteelisa. 

 

The results of the window frame LCA demonstrate that the environmental impacts do not vary greatly between AM and CM (Figure 1). AM consumes more energy by 6.2% MJ, has 84.5% less heat waste, 0.9% less Abiotic Depletion of Fossil Fuels, and 2.4% higher global warming emissions. AM of the full size frame is greatly expensive and time consuming in comparison with CM (Figure 2). The environmental impacts of CM could be potentially reduced by decreasing aluminum extrusion waste (focus on improving the precision and accuracy of the extruded aluminum dimensions to minimize post-processing, e.g., milling). The environmental impacts and the cost of AM could be potentially reduced if using larger aluminum wire sizes without compromising the frame geometry.  

Figure 1:  Environmental impacts of CM vs. AM of the window frame


Figure 2:  Cost of CM vs. AM for the window frame through life cycle stages


The bracket LCA showed that the environmental impacts of AM are at least 40% lower than CM (Figure 3). AM consumes less water and energy than CM, and there are fewer human health, ozone layer, and acidification impacts (Figure 2). Two AM technologies were analyzed for bracket manufacturing: direct metal laser sintering (DMLS) and electron beam melting (EBM). Across three production methods analyzed, aluminum brackets have greater greenhouse gas emissions and consume more energy than steel brackets despite larger transportation payload distance for steel. However, aluminum bracket production requires less water consumption. AM cost of the multifunctional bracket is 4 – 10 times greater than CM (Figure 5). As the greatest environmental impacts come from the raw material processing (in AM and CM), the impacts could be potentially reduced by decreasing initial mass (optimization) of a component rather than locally sourcing material.

 

Figure 3:  Greenhouse gas emission (in kg CO2) of CM vs. AM (DMLS and EBM) for the bracket


 

Figure 4:  Environmental impacts of CM vs. AM (DMLS and EBM) for the bracket; on the left: Energy consumption per bracket (in MJ LHV); in the middle: Human health impact per bracket (in 10e-6 DALY); on the right: Water source depletion per bracket (in m3 water eq.)

 

Figure 5:  Manufacturing cost of CM vs. AM (DMLS and EBM) for the bracket  

 

The assessment framework that is currently under development focuses on the technical applicability or feasibility of additive manufacturing methods and their schedule, cost, and environmental impacts relative to conventional manufacturing methods. It’s current draft version (Figure 6) includes 7 functions: the “applicability analysis (A)”, “gather data for S, E, and C analyses”, “schedule analysis (S)”, “environmental impact analysis (E)”, “cost analysis (C)”, “sensitivity analyses”, and “final results”. The framework requires user inputs about the building component (geometrical constraints and type of material), the information about the project (number of components, geographical locations of CM, and the choice about the AM’s location, type of CM technology used for the component), and about the scope of the assessment (life cycle stages, the information about the CM processes, transportation, the mass and the waste per one component in each stage, and the cost and the schedule either of one CM component or for the project). The information about AM technologies is extracted from an external up-to-date database. The outputs of the last function are used by analyzers or clients to make an informed decision about using AM or CM on a project.

 

 Figure 6: A high-level diagram of the formalized semi-automated framework’s workflow to analyze whether the use of AM technologies to make a type of building component is advantageous or not.

Please contact Natasa Mrazovic (natasam@stanford.edu) if you are interested in this project.

Overview

The first year’s research showed that Additive Manufacturing (AM) technologies, popularly known as 3D printing, are unlikely to take over the construction industry very soon. Nevertheless, the findings from the first year also show that we should attempt to harvest the benefits AM is offering, like mass-production of custom parts, just in time deliveries, and production of components with complex geometries.  

The use of AM in the Architecture-Engineering-Construction (AEC) industry has been limited by technological maturity and cost. However, AM of large metallic building components is almost technologically feasible today. For the foreseeable future, AEC industry practitioners will need a way to assess the applicability, the cost, environmental, and project performance impacts of additively manufactured (AM) specific building components over conventionally manufactured (CM) counterparts. For this purpose I propose to: (1)analyze potential assessment methods in both, AM and AEC fields, for benchmarking AM against conventional manufacturing (CM); (2) develop conceptual analytical assessment framework for AM’s application in AEC; and (3) formalize a methodology for the preliminary evaluation of AM (applicability and cost-effectiveness) to manufacture a specific building component.  The formalized framework will be validated by comparing the results with previously conducted feasibility analyses.

Project Background

Research Motivation & Industry Example

Motivated by AM’s capacity to impact the AEC fields, we developed and conducted a feasibility study (attached) in collaboration with Permasteelisa’s R&D group to evaluate the ability and costs to 3D-print multifunctional curtain wall (CW) segments and large-scale CW components, specifically a one-story metallic frame, as a single element on a construction site to eliminate the cost of extrusion, assembly, transportation and packaging (Figure 1 ) .