Homes of the Future?

A First: A Fully 3D-Printed House Made from Bio-Based, Low-Carbon Materials

One of my recent articles focused on the big potential of 3D-printed houses. However, the printing process used up until now has only created walls. Carpenters are still needed to install doors and windows, and build the roof. On the plus side, just printing wall panels produces walls of greater tensile and flexural strength and in half the time of traditional practices.

Modular building, panelized construction, and building with structural insulated panels (SIPs) have received attention as new technologies with potential to speed up production and reduce waste. Widely used in some countries, these innovations have been slow to be incorporated in the U.S. While 3D printing could just be another one of these new approaches, it could actually help solve the construction industry’s labor and supply-chain issues.

One building company, Mighty Buildings, has produced the first 3D-printed net-zero home using printed components. The one sustainable drawback of its process, as well as that of all other 3D efforts, is that they use concrete for their walls. The production of cement, the binder in concrete, accounts for around 8 percent of all greenhouse-gas emissions worldwide. In addition to high embodied carbon, concrete has poor insulative properties. Fortunately, new concrete mixes are being fed into the 3D-printing nozzles that are showing promise of reducing emissions by half or more. 

The latest campaign in green building is to utilize materials that have low embodied carbon while avoiding materials such as spray and rigid foam, steel, and concrete — all currently being used in 3D-printed houses. However, 3D printing may be on the cusp of conquering this challenge: The University of Maine has produced a prototype printed house made entirely of bio-based, low-carbon materials. The materials exuded by its printer are composites of wood fibers and bio-resins. About 60 percent of the material is wood flour by weight and the rest is resin. According to the team, this building is fully recyclable.

Another breakthrough with the BioHome3D is that all components — floors, walls, and roof — are printed and with high R-values (insulation values). Culminating decades of research by the university team, the printed material resists decay and rot because of the resin that prevents water intrusion. When it is time to recycle, the building can be ground up and sent through a printer to produce another house. Wall and roof sections are printed with an inner and outer layer connected by a truss-like reinforcement. The cavity between the two layers is filled with cellulose insulation. This design allows for increasing the wall thickness and improving the insulative performance as needed.

Construction is a traditional industry, slow to change. It is, however, moving toward net-zero performance buildings. Maybe it will also start making houses that are carbon storage units.

Heat Pumps Are Becoming a Part of Our Future

Lower-Income Families Can Now Have Better Health, Reduced Utility Bills, and More Comfort

Nearly half of residential buildings in the U.S. were constructed before 1973, when building code energy standards were virtually nonexistent. As a result, most homes and residential buildings still rely on old technologies for heating and cooling: furnaces and boilers for heating and big rooftop air conditioning units for cooling.

Heat pumps, however, are gaining traction. The same piece of equipment can provide heating and cooling. Heat pumps are powered by electricity but have efficiencies 3-5 times that of fossil-fuel heating systems. Despite the name, heat pumps do not generate heat; they move it from one place to another. In heating mode, they absorb latent heat energy from the outside air, even cold air, and transfer this heat to indoor air. The condenser and evaporative coil, which are located outdoors, use a liquid called a refrigerant to soak up heat and move it indoors or capture it indoors and release it outside, depending on where heat or coolness is needed. The source of thermal energy for a heat pump can be the air (an air-source heat pump) or the ground (a ground-source heat pump). 

Refrigerators are heat pumps but with the condenser located at the back or bottom of the appliance. We feel heat around a refrigerator because it is pulling heat out of the cold air inside the unit, thereby making it even cooler. A big plus that heat pumps offer is improved indoor air quality because there is no combustion.

There are also heat-pump water heaters and heat-pump clothes washers and dryers. Efforts are underway to create a household system where one compressor placed outside can power these various heat-pump services. 

It has been known for decades that saving energy is cheaper than creating fossil-fuel energy. Investing in such efficiencies has among the best return-on-investment. In 2021, Americans spent an average of $1,380 per year on energy bills. Installing efficient windows; preventing air leaks; insulating roofs, attics, crawlspaces and walls; and changing existing lighting to LEDs, together with investing in heat pumps, can cut utility bills by more than half.

The Inflation Reduction Act that President Biden signed into law last August invests $369 billion in climate reducing strategies over the next decade — a big part of which will go for energy retrofits and electrification of homes for moderate-income and disadvantaged families. The many jobs created by doing these retrofits and improvements will be local and primarily benefit small companies. 

If buildings around the globe are electrified and the sources of that electricity are from renewables, by 2050, one-sixth of the world’s total greenhouse-gas emissions would be eliminated.

People Can Make Rain

Reversing Destructive Land-Use Patterns Can Improve Local Water Cycles

Through an examination of tree rings dating back 2,500 years, scientists have determined that from the 1500s until the 1970s, California was uncharacteristically wet. The latter 130 years of this period cover the modern development of the state. Understandably, planning parameters have been based on overly optimistic figures for rainfall. Not only are our expectations outside the long-term range of weather patterns, but we are making the climate hotter and drier through human-induced climate change.

There are two moisture cycles in nature. The most widely understood one is rain flowing down rivers to the sea, where it evaporates from the ocean surface, condensing into clouds that drift over land to rain again. This, however, only accounts for about half of rainfall. The second cycle is a smaller, more local one. Moisture evaporates from plants, trees, and the soil, making clouds overhead and subsequently falling as rain in the region.

To make clouds, microscopic particles are needed. These were thought to be inert minerals like dust. Only within the past 50 years have scientists begun understanding that bacteria can also be nuclei around which water vapor can coalesce. Studies have shown that cloud-making bacteria exist in every part of the world. One study of cloud-water revealed 28,000 different species of bacteria. Plants and algae create conditions for microbe propagation, of which some become lifted by winds and attract water vapor. Bacteria multiply rapidly and are among the most resilient organisms on the planet.

The knowledge that microbes from plants and soil play a central role in rain cycles over land has profound implications. For example, the removal of vegetation by overgrazing or exposing bare soil in monocrop farming can create conditions for drought. Conversely, the restoration of a plant-rich ecosystem could increase precipitation. Cloud-seeding bacteria can be deliberately cultivated to boost water cycles. 

Reversing destructive farming, ranching, and forestry practices creates opportunities to restore carbon stocks in soil, plants, and trees. Healthy, carbon-rich soils store a great deal of water and foster abundant microbial communities, leading to increased evaporation, water vapor, and clouds. Evaporation is usually seen as a loss, something to be minimized. We need to change this perspective and start seeing it as a source of precipitation.

A Dutch company, Water Makers, has a project to transform the upper half of the Sinai desert from brown to green, filled with farms, plants, animals, and forests. Centuries ago, the Sinai was green with life, before degrading activities by people dried it out.

With droughts and wildfires in California ever more frequent, it is time to start transforming our industrial agriculture and landscape into carbon-sequestering soils and plants, thereby improving the local rain cycles.

Coming Soon: Plant-Based Roads

Plant-Derived Material Can Make Our Roads Carbon-Negative

With all the attention focused on shifting from fossil fuels to renewables, there has been less emphasis on the hundreds of other products made from petroleum and finding substitutes for them. Some of the more common commodities are plastics, shoes, lubricants, paints, sports equipment, synthetic fibers for clothing, and building materials, including roofing.

One ubiquitous product is bitumen, a fossil-fuel-derived binder that holds asphalt aggregate together. A company in Norway is recycling old, damaged roads by using a plant-based binder instead of bitumen. Currently, it has applied this process only to repairing roads. Because Norway is far north, its roads suffer from repeated freeze-thaw cycles. The non-petroleum bioasphaltic binder it employs is lignin — a wood-based material essential to creating structure for trees and plants. The company utilizes a machine called the Carbon Crusher to grind up the top layer of damaged roads before applying the lignin to rebind the ground-up aggregate into a new, durable top layer. 

Approximately 18 billion tons of asphalt make up U.S. roads. All these roads need to be maintained. Asphalt is energy- and resource-intensive, contributing substantially to climate change. Lignin, one of the most abundant natural polymers, is an ideal substitute for crude oil bitumen. Because trees capture CO2 as they grow, using lignin on roads sequesters carbon. This significantly shrinks the carbon impact, especially for road repair. When the road aggregate is recycled, as in Norway, the use of new material is avoided and their associated carbon emissions from production and transportation, often making the entire process carbon-negative.

The process of rehabilitating roads with lignin is faster, cheaper, and more durable than what has been the case with standard bitumen repairs. The biggest plus, however, is its environmental benefits. In Norway, they are finding that lignin is more flexible than bitumen, allowing the repaired surfaces to adapt better to the harsh weather, preventing cracks and making the repairs last longer.

Sweden and the Netherlands are also repairing roads with lignin. The process is starting to be applied to building new roads, but with fewer environmental advantages. The ultimate aim, however, is to stop building new roads — which incentivizes more driving — and focus on better care of existing highways.

It is critical that substitute products, processes, and technologies be found for the myriad of common petroleum-based products that dominate our modern life. What is now underway for asphalt is an instructive model.