News Treehugger Voices Community of 3D-Printed Net-Zero Homes Proposed for California 3D-printed, sustainable, healthy, solar-powered, what's not to love? By Lloyd Alter Lloyd Alter Facebook Twitter Design Editor University of Toronto Lloyd Alter is Design Editor for Treehugger and teaches Sustainable Design at Ryerson University in Toronto. Learn about our editorial process Published March 23, 2021 10:03AM EDT Mighty Home Share Twitter Pinterest Email News Environment Business & Policy Science Animals Home & Design Current Events Treehugger Voices The press release starts with a bang: "Palari Group, a development company dedicated to re-imagining real estate through innovative and sustainable building strategies, and Mighty Buildings, a construction technology company that is revolutionizing the construction industry by using 3D printing and robotic automation to create beautiful, affordable, and sustainable homes, today announced they had secured a site and commenced development of the world's first community of 3D-printed zero net energy homes located in Rancho Mirage, California." Alexey Dubov, co-founder and COO of Mighty Buildings says: "This will be the first on-the-ground actualization of our vision for the future of housing - able to be deployed rapidly, affordably, sustainably, and able to augment surrounding communities with a positive dynamic." Basil Starr, founder and CEO of Palari, says: "3D printing allows us to build faster, stronger and more efficiently, making it integral to our platform of streamlining home-building process centered on sustainability of construction, materials, and operations." LA Times screen capture The media are all excited, calling it the future of housing. "All energy needs will be supplied by solar power," notes The Hill, "and owners will have the option to install Tesla Powerwall batteries and electric vehicle chargers for a 'fully integrated electric car-home experience.'" According to Mighty Buildings, the houses will get built twice as quickly, with 95% fewer labor hours, and 10 times less waste. They will have Darwin by Delos state of the art wellness tech. It pushes so many Treehugger buttons: 3D printing, beautiful, healthy, and sustainable. So what's not to love? When you go to the Mighty Homes website, you can see two basic construction concepts: a Mighty Mod Studio that is 3D-printed as a complete unit, and then there is the Mighty Kit system which is being used in the Rancho Mirage project. But before we look at the Kit, we have to go back to define what a 3D-printed house actually is. 3D printing is defined as "a process of making three-dimensional solid objects from a digital file. The creation of a 3D-printed object is achieved using additive processes. In an additive process, an object is created by laying down successive layers of material until the object is created. Each of these layers can be seen as a thinly sliced cross-section of the object." Mighty Homes The Mighty Kit homes are not laid up with successive layers. They are made of prefabricated panels composed of various components, a version of what is called structural insulated panels or SIPs that are then assembled on site. Panel Detail. Mighty Homes In this case, the body of the SIPs is 3D-printed out of glass-fiber reinforced thermosetting plastic that is hardened with ultraviolet light, filled with polyurethane foam, braced with a steel frame, and finished inside with drywall. Extruded plastic panels. Royal Plastics They are using a 3D printer to make the plastic panel, but this makes no sense; 3D printing is slow and expensive and usually used for complex forms. These panels could be made more quickly and cheaply using extruded plastic panels, which is exactly what Vic de Zen has been doing at Royal Plastics for 30 years in Canada and the Caribbean. Why would you 3D print this?. Mighty Homes So yes, a 3D printer is used, albeit for no good reason because there are way better ways to make a panel, but under no definition I have ever heard of would this be considered a 3D-printed house, it is a 3D-printed component. A foam and plastic sandwich. Mighty Homes Then there is the question of sustainability. The General Services Administration explains that "the basic objectives of sustainability are to reduce consumption of non-renewable resources, minimize waste, and create healthy, productive environments." This is a foam and plastic sandwich made entirely of non-renewable materials. Thermoset plastic panels are not recyclable, and the plastic resins are made from fossil fuels. The polyurethane foam insulation is essentially a solid fossil fuel. Nowhere in this world are they considered sustainable materials. Mighty claims that there are "savings of 2.3 tons of CO2 emission per 3D printed home" but sprayed polyurethane has the highest embodied carbon and greenhouse gas emissions of any insulation, 3 kilograms of CO2 equivalent emissions for every kilogram of insulation. As for it being a healthy home, the reinforced plastic and the foam outgas volatile organic compounds and are full of flame retardants. In summary, it's not really 3D-printed, it is definitely not sustainable, and throwing in a Darwin system doesn't make it healthy. I will not get into the details of the site plan; renderings are often not representative of the final result, but Twitter is agog. Now to be fair, this writer is really biased, and tends to recommend avoiding plastics and suggests using natural materials, has expressed reservations about 3D-printed houses before, and has some skepticism of Delos and its wacky ideas about healthy homes, not to mention a bias against auto-centric single-family suburban development in the desert. Finding it all wrapped together in one neat package like this is a rare treat, so I should point out that the roofs do have solar panels, it's not all a hot mess.