While 3D printing no doubt opens some amazing doors when we apply it to the concept of sustainable housing, it also has a natural set of limitations. As Cristopher Brenny notes, writing for Arch Daily, the true sustainability factor of a building is defined by the materials used for construction, as well as access to those resources in nearby areas. Transporting building materials, or previously printed pieces of a structure, only adds to the carbon footprint of a structure.
Brenny points out that if recycled materials are used for construction, they will likely be limited to ABS or PLA plastic (as we discussed in our last post, two very different kinds of plastics). He rightly notes that the desirability of a 3D printed plastic structure, "both practically and aesthetically," is still an unknown quantity. While 3D printed buildings may have dramatic appeal in poverty stricken areas, where there is almost no other alternative for safe, clean housing, its ability to compete with traditional construction methods, when they are viable options, remains to be seen.
Using the example of a 3D printed house being constructed by a group named Dus Architects in Amsterdam, Brenny notes that traditional structures do have some advantages, sustainably speaking, over a printed building. The Dus Architects project is constructed from printed bricks, 2x2x3.5 meters in dimension, which are then back-filled with concrete for stability. Concrete carries a large carbon footprint, especially when opposed to wood, which sequesters carbon by its very nature. While even traditional structures must be reinforced, the limited amount of building materials that can currently be employed in 3D printing leave a builder with few options.
There are, however, other methods for printed construction that add to sustainability. Another project, D-Shape, uses sand as a substrate, mixing with a binder that renders it as hard as marble. In this methodology, there is no need to reinforce the structure with concrete or iron. The availability of sand, gravel, or dust virtually everywhere that a habitable structure may be created further adds to D-Shape's sustainability.
Lest you think that 3D printed structures are the sole purview of high-tech international construction firms, CNET reported in late August on Andrey Rudenko, a contractor with a background in engineering from Minnesota. Rudenko developed his own 3D printer, which he then utilized to build a castle in his backyard. While the structure was far from liveable, measuring just 10 feet by 16 feet with a height of 12 feet, as a proof of concept it was highly successful.
Rudenko's printer extrudes a specialized mixture of concrete, which he also developed, in layers 10 millimeters by 30 millimeters, slowly building up the structure, which he reinforced in key areas with steel or re-bar (necessitated by his use of concrete). The machine is adjustable, able to print layers in different dimensions, depending on the project at hand. Rudenko's next task is to print a full sized house, for which he is seeking investors and a warmer climate, where he can run his printer 24/7 to complete the building.
The 3D printing technology that Rudenko used to build his castle is becoming far more commonplace, and with the convenience of the internet, designs are readily available to any who wish to try their hand at a project. His machine is based on a RepRap project, a free, open-source, self-replicating 3D printer. With a moderate amount of technical knowledge and personal education, the ability to begin sustainable manufacturing in-home is already available to almost anyone.