The 1,200 square foot home has three bedrooms, two full bathrooms and a covered porch. Still, it took only 28 hours to build the home’s concrete walls – that’s because they’re printed, reducing the standard building plan by at least 4 weeks. Using automated computer technology and a patented concrete mix, Habitat for Humanity recently completed the first of many planned 3D-printed houses in Williamsburg, Virginia and elsewhere.
The new owner, April Stringfield, and her 13-year-old son are happy to know the home will be theirs. Ms. Stringfield has worked as a laundry supervisor for 5 years at a local hotel, but her income is less than 80% of the area’s median income. Needless to say, becoming a homeowner seemed out of reach – until it was accepted into one of Habitat for Humanity’s 3D-printed houses. “My son and I are so grateful,” she said at the inauguration of the home. “I’ve always wanted to be a homeowner. It’s a dream come true.”
Habitat for Humanity has built hundreds of thousands of affordable homes for people who need them.
3D printing is a fairly new technique in the construction sector, with the aim of improving the economy and mitigating the environmental impact. It is an innovative area that combines knowledge of traditional construction with digital manufacturing. The elimination of formwork plus several other major benefits has great potential and has captured the attention of the construction industry.
Why 3D printing?
- It saves up to 15% per. square feet in construction costs for contractors.
- It provides better temperature retention, reducing the cost of heating and cooling for homeowners.
- It is resistant to tornado and hurricane damage.
3D-printed houses are already being built and sold to the general public.
How to build 3D-printed houses
The concept of additive manufacturing – the more technical term for 3D printing – dates back to the 1980s, but has become much more popular in the last decade. 3D printing begins with a digital file of a house design. Large robotic arms on a swivel produce fully functional houses, as they layer by layer deposit material to build the house in three dimensions, one layer at a time.
To Ms. Stringfields Habitat for Humanity Home, Alquist used a patented concrete mixing and extrusion machine to print exterior and interior walls, which were reinforced with steel during the printing process. Afterwards, the outer walls were sealed with a clear or tinted coating that prevents moisture from transferring through the concrete. The contractor built traditional side cladding on the gables and used standard brick on the porch posts.
Homeowners can choose a standard gray concrete color or choose from a variety of attractive earth colors to give the home a custom look.
After Alquist finished printing the walls, traditional builders constructed the roof, ran plumbing and wiring, and installed interior floors and other finishes. Through the Williamsburg chapter of Habitat, contractors, subcontractors, and other volunteers donated their time to complete the rest of the house.
Life cycle assessment of 3D-printed houses
The Life Cycle Assessment Framework (LCA) is used to quantify the environmental impact of raw material extraction and production as well as energy consumption during design and operational phases. Do you want statistics? A study conducted in the United Arab Emirates looked at the construction process of a single-storey 3D-printed house to perform the comparative assessment compared to traditional concrete construction.
The economics of the selected structural systems were examined through life cycle cost analysis (LCCA), which mainly included construction costs and energy savings. An eco-efficiency analysis was used to aggregate the results of LCA and LCCA into a single framework to assist in decision making by selecting the optimal and most eco-efficient alternative.
The results revealed that houses built using additive manufacturing and 3D-printed materials were more environmentally friendly. The conventional construction method had greater impacts compared to the 3D printing method with a global warming potential of 1154.20 and 608.55 kg CO2 equivalents, non-carcinogenic toxicity 675.10 and 11.9 kg 1,4-DCB and water consumption of 233 , 35 and 133 m2. .
The 3D-printed house also proved to be an economically viable option with a 78% reduction in total capital costs compared to conventional construction methods. The combined environmental and economic results revealed that the overall process of the 3D-printed house had higher eco-efficiency compared to concrete-based construction. The main results of the sensitivity analysis showed that up to 90% of the environmental impacts in 3D print mortars can be mitigated with decreasing cement ratio.
Environmental impact of 3D-printed houses
Alquist – the company behind Habitat for Humanity 3D printing – uses the technology to create design while lowering the cost of housing and infrastructure in economically needy and underserved communities. Each Alquist home is equipped with Virginia Tech’s proprietary Raspberry Pi-based monitoring system, which monitors the indoor environment, provides safety and emergency management, optimizes energy consumption and analyzes residents’ comfort and space utilization.
Alquist also installs a 3D printer in the kitchen of every home it builds. The homeowner receives a downloadable computer file that allows them to print buttons, light switch covers, and other replaceable parts.
While 3D-printed houses are still uncommon, the Williamsburg house symbolized the potential of affordable homes that limit the use of natural resources such as trees. Each new home built by Habitat for the Humanity Peninsula and Greater Williamsburg is EarthCraft certified. EarthCraft is a voluntary green building program that serves as a plan for healthy, comfortable homes and works to both reduce consumption bills and minimize environmental impacts.
The construction of each home built by Habitat for the Humanity Peninsula and Greater Williamsburg is a collaboration between volunteers, house sponsors and the buyers of the home. The participating families provide at least 300 hours of work building their own and other families’ homes, called sweat capital. Habitat’s homebuyer program resulted in monthly mortgage repayments of up to 30% of Ms. Stringfields income, including her property taxes and homeowners insurance.
3D-printed houses are inherently resistant, cost-effective and have a robust construction. They can help make housing more affordable and are likely to become another tool in the toolkits to combat homelessness and the effects of the climate crisis.
Interested in learning more about the possibilities of 3D printing? Check out these articles: hydropower prototypes, EV parts and carbon fiber bikes.
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