The 1,200-square-foot home includes three bedrooms, two full bathrooms, and a covered front porch. However, the concrete walls of the house only took 28 hours to build – due to their printing, which shortened the standard construction schedule by at least 4 weeks. Using robotic computer technology and a patented concrete mix, Habitat for Humanity recently completed the first of several 3D-printed homes planned 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 worked as a laundry supervisor for 5 years at a local hotel, however, her total income is less than 80% of the average income in the area. Needless to say, becoming a homeowner seemed so far-fetched – until you were accepted into one of the 3D-printed homes from Habitat for Humanity. “My son and I are so grateful,” she said at the home dedication ceremony. “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 the people who need them.
3D printing is a fairly new technology in the construction sector, with the goal of improving the economy and mitigating environmental impacts. It is an innovative area that combines the knowledge of traditional building and digital fabrication. Elimination of formwork as well as many other major benefits has great potential and caught the attention of the construction industry.
Why 3D printing?
- Saves up to 15% per square foot in construction costs for contractors.
- Provides better temperature retention, reducing heating and cooling costs for homeowners.
- It is resistant to hurricane and hurricane damage.
3D-printed homes are already being built and sold to the general public.
How 3D printed homes are built
The concept of additive manufacturing – the more technical term for 3D printing – dates back to the 1980s, but has become more and more popular in the past decade. 3D printing starts with a digital home design file. Large robotic arms on a rotary produce fully functional homes that, layer by layer, deposit materials to build the house in three dimensions, one layer at a time.
For Ms. Stringfield’s home, Habitat for Humanity, Alquist used a patented extrusion and concrete mix machine to print the exterior and interior walls, which were reinforced with steel during the printing process. Next, the outer walls were closed with a transparent or colored layer that prevents moisture from moving through the concrete. The contractor incorporated traditional siding on the roof trusses and used standard bricks on the porch columns.
Homeowners can choose a standard gray concrete color or choose from a range of attractive earth tones to give the home a custom look.
After Alquist finished printing the walls, traditional builders built the roof, run plumbing and wiring, and install interior floors and other finishes. Through the Williamsburg branch of Habitat, contractors, subcontractors and other volunteers donated their time to complete the remaining parts of the house.
Life cycle assessment of 3D printed homes
The Life Cycle Assessment (LCA) framework is used to determine the environmental loads of raw material extraction and manufacture, as well as energy consumption during the construction and operation phases. Want stats? A study conducted in the United Arab Emirates looked at the construction of a 3D-printed single-storey house for a comparative assessment against traditional concrete construction.
The economics of the selected structural systems were examined by life cycle cost analysis (LCCA), which mainly included construction costs and energy savings. Environmental efficiency analysis was used to aggregate the results of the LCA and LCCA into a single framework to aid decision-making by selecting the most optimal and environmentally efficient alternative.
The results revealed that homes built using additive manufacturing and 3D-printed materials were more environmentally friendly. The traditional construction method had higher effects when compared to the 3D printing method with GWP 1154.20 and 608.55 kg CO2eq, non-carcinogenic toxicity 675.10 and 11.9 kg 1.4-DCB, and water consumption 233.35 and 183.95 m3, respectively.
The 3D printed home was also found to be an economically viable option, with a 78% reduction in total capital costs compared to traditional building methods. The combined environmental and economic results revealed that the overall process of the 3D-printed house had a higher environmental efficiency compared to the concrete-based construction. The main results of the sensitivity analysis showed that up to 90% of environmental impacts can be mitigated in 3D-printed mortar by reducing cement ratios.
Environmental Impact of 3D Printed Homes
Alquist — the company behind 3D printing for Habitat for Humanity — uses the technology to create designs while lowering the cost of housing and infrastructure in economically struggling and underserved communities. Every Alquist home comes equipped with Virginia Tech’s Raspberry Pi monitoring system, which monitors the indoor environment, provides security and emergency management, optimizes energy consumption, and analyzes occupant comfort and space use.
Alquist also installs a 3D printer in the kitchen of every home it builds. The homeowner receives a downloadable computer file that allows him to print knobs, light switch covers, and other replaceable parts.
While 3D-printed homes remain uncommon, the Williamsburg home symbolizes the potential of affordable homes that limit the use of natural resources such as trees. Every new home built by Habitat for Humanity Peninsula and Greater Williamsburg is EarthCraft certified. EarthCraft is a volunteer green building program that serves as a blueprint for healthy, comfortable homes that reduces utility bills and reduces environmental impacts.
Each home built by Habitat for Humanity Peninsula and Greater Williamsburg is a collaborative effort between volunteers, home sponsors, and home buyers. Participating families save at least 300 hours of labor to build their own and other families’ homes, and this is called race equity. Habitat’s homebuyer program resulted in monthly mortgage payments of no more than 30% of Ms. Stringfield’s income, including property taxes and home insurance.
3D printed homes are flexible in nature, cost effective and have robust construction. It can help make homes more affordable and is likely to become another tool in the toolkits to combat homelessness and the effects of the climate crisis.
Interested in learning more about the capabilities of 3D printing? Check out these articles: Hydro models, EV parts, and carbon fiber bikes.
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