29 Sustainable Building Materials You Can Use Today

Images of sustainable building materials cut into the shapes of letters which are then used to spell the word "sustainability."

With society becoming increasingly environmentally conscious, more and more people are on the lookout for sustainable building materials to use in their projects.

Not only do eco-friendly buildings significantly increase the resale value of a property in a forward-thinking market, but they can also help you save on maintenance and utility costs.

And more recently, the skyrocketing costs and long supply delays are throwing a wrench in homebuilding as an entire industry. So it may just be a perfect time to start exploring some of these alternatives for building your next home.

Sustainability is one of those buzzwords that gets bandied around by all and sundry these days.

Whether in the context of sustainable building materials, sustainable transport, sustainable food supply, or any other sustainability-related topic that appears in the media or is discussed over the breakfast table, sustainability seems to be on everyone’s lips.

Everyone from Jon Oliver to my ten-year-old daughter talks volubly about carbon footprints and global warming whenever the subject arises.

Two out of every ten of the world’s biggest companies have publicly announced net-zero emissions targets. The United Nations says that to limit global warming to 1.5°C, we must reduce greenhouse gas emissions by 45% by 2030 and hit net zero by 2050.

It’s clear that the corporate world and the international community are taking climate change seriously and taking steps to mitigate the impact of human activity on global temperatures, sea-level rises, and the other impacts accompanying global heating.

Global warming is the highest-profile and furthest-reaching problem that humans face today. But there are many other interrelated issues that we must deal with if we are to achieve environmental sustainability.

In addition to climate change, communities worldwide face issues regarding the use of natural resources, waste production, air pollution, water pollution, deforestation, overfishing, etc.

But what can we do in the construction industry to tackle these issues and become more sustainable to benefit everyone now and in the future?

The answer is “quite a lot.”

According to the UN Environment Programme, the built environment accounts for approximately 40% of global energy use, uses vast amounts of natural resources, and generates a lot of waste that we must dispose of or (ideally) recycle.

So there’s a lot the construction industry can do to achieve sustainability. But, for this article’s purposes, we’ll focus on one particular aspect: the materials we use in construction.

In this article, we’ll be taking a look at some of the top building materials that, for one reason or another, can be considered sustainable, green, or somehow better for the planet than their standard alternatives.

First, we’ll attempt to provide a more precise definition of sustainability and the factors we should consider when contemplating whether to call a building material “sustainable.

What Are Sustainable Building Materials?

A collage of sustainable building materials, including bamboo, sustainable timber, mud bricks and a high-rise building incorporating plants.
Sustainability means meeting our present needs without harming the ability of our descendants to meet theirs. Sustainable building materials can help us to achieve this and safeguard the well-being of future generations.

To better understand what “sustainable building materials” means, it’s helpful to know where the term “sustainable” came from in environmental matters.

Let’s think back to the late 1980s when Ronald Reagan was in Germany, calling for the fall of the Berlin Wall. The United Nations was putting the final touches to an important sustainable development document known as the Brundtland Report.

The Brundtland Report Clarifies What is Meant By Sustainable Development

The term “sustainable development” was coined in 1987 by the United Nations World Commission on Environment and Development in the Brundtland Report published that year.

The report defines sustainable development as “development that meets the needs of the present without compromising the ability of future generations to meet their own needs.”

Sustainability relies on the three pillars of the economy, society, and the environment. The interactions of these factors are illustrated in the following infographic.

Infographic illustrating the dependence that the economy has on society and the environment. There are three diagrams showing the interaction of society, environment and the economy. One shows the three elements as a Venn diagram overlapping equally, the second shows the economy wholly withing society, both of which are within the environment. The third shows a sustainability "roof" supported by the three pillars of social, environmental, and economic stability.
Purvis, B., Mao, Y. & Robinson, D. Three pillars of sustainability: in search of conceptual origins. Sustain Sci 14, 681–695 (2019). https://doi.org/10.1007/s11625-018-0627-5, CC BY-SA 4.0, via Wikimedia Commons

This broad definition has been explicated in subsequent work coordinated by the UN, such as the Earth Summit, which took place in Rio de Janeiro in 1992.

This work culminated in the adoption of the 17 Sustainable Development Goals by the United Nations General Assembly in 2015. These 17 goals cover 2015-2030 and focus on important themes such as poverty, climate change, peace, justice, and environmental degradation.

Definition Of Sustainable Building Materials

The broad aim of sustainable development is worthy – nobody wants to live a life of excess which means their children and grandchildren will be unable to meet their own needs decades from now.

But it is somewhat vague and lacking in detail. So, let’s think about what sustainability means in the context of building materials.

Environmental Sustainability

Building materials can impact the environment in several ways, as follows.

  • Embodied carbon: Materials such as concrete require a lot of energy to produce, which increases the carbon footprint of any construction project that uses it.
  • Depletion of natural resources: Minerals like limestone and iron ore are finite resources that should be preserved.
  • Waste going to landfill: The use of packaging in construction is a particular issue, comprising a third of all construction waste.
  • Transportation: Particularly in remote areas, transportation can be a significant source of greenhouse gas emissions linked to building materials.
  • Hazardous or polluting chemicals: Some materials are manufactured using harmful chemicals. Sometimes chemicals can leach out of building materials or are required for maintenance (e.g., creosote for preserving timbers).
  • Biodiversity impacts: Some raw materials can impact biodiversity, for example, the growth of monocultures or infrastructure interfering with migration routes.

If we can reduce or eliminate any of these factors, we can greatly enhance the sustainability of our building materials.

Model wooden buildings  with green leaves arranged above them to indicate sustainability.
There are several factors that green building materials must possess. These include low embodied carbon, locally sourced and renewable materials, and others.

A building material must satisfy as many of the following factors as possible to be more sustainable.

  • Low energy requirements in the manufacturing process.
  • We should obtain raw materials from renewable sources, such as sustainably managed forests or other crops.
  • Materials preserve biodiversity.
  • Reclaimed materials that we reuse are more sustainable.
  • The material can be reused or recycled at the end of its life.
  • We source the material locally, which cuts down on the energy (and cost) of transportation.
  • No harsh chemicals are used in the manufacture of the material or for its maintenance.

The basic message here is that to deliver truly sustainable development, we must use building materials that do not deplete non-renewable natural resources and which have no harmful impacts on the environment.

Sustainability is wider than that, as shown in the diagrams above, which make it clear that sustainability must take account of social and economic factors as well as the environment.

Social Sustainability

The extraction, manufacture, and use of building materials can be made socially sustainable by ensuring the associated activities align with the following.

  • Promote universal human rights.
  • Ensure people have access to sufficient resources.
  • Communities are healthy.
  • People are safe.
  • No groups are discriminated against or disadvantaged.

Economic Sustainability

Likewise, the use and manufacture of sustainable building materials should be aligned with the following economically sustainable aims.

  • Communities have access to resources they require, including economic resources.
  • The local economic system operates effectively so everyone can make a good living.
  • Companies manage their resources responsibly to be profitable over the long term.

The Fairtrade standards can help us identify products traded on terms that are fair between buyers and farmers, promote social rights for workers, and ensure a fair price for produce.

Using only sustainable building materials is a lofty ambition, which is aspirational at best for most of us. However, applying these principles to our construction projects can go a long way to meeting the needs of the present without hurting the chances of our great-grandchildren doing the same.

I’ve written a more detailed post about how the sustainability of building materials can be assessed, entitled “What Are Sustainable Materials: How To Know for Sure,” which you can read if you’re interested in the principles that underpin this kind of assessment and the available tools and certifications.

Certification Of Building Materials and Projects

Collage of innovative buildings with the LEED Certified marks overlain.
Slide taken from the LEED Promotional Presentation made available on the USGBC website.

To help transform the way buildings are designed, built, and operated, the US Green Building Council (USGBC) created Leadership in Energy and Environmental Design (LEED®). LEED is a voluntary framework of rating systems that seeks to improve the health and environmental performance of the construction industry.

LEED certification is awarded to projects that meet the scheme’s requirements and earn sufficient credits by demonstrating sustainability in materials, waste, water, energy, and other factors.

LEED credits are awarded for things such as the sourcing of raw materials, material ingredients, and waste management. More information is available on the LEED website.

Next, let’s look at some examples of sustainable building materials.

Sustainable Materials – Top Examples of Green Building Materials

Sustainable building materials will not only help to save the planet, but they can help to cut building costs if used appropriately.

Using the most suitable materials is the right thing to do for the environment and, in many cases, is the right thing for the bottom line of your project.

We have compiled a selection of eco-friendly building materials based on existing knowledge and research.

If you think we’ve missed any, please get in touch and let us know.

1. Bamboo

Interwoven bamboo poles forming a wall.
Bamboo is a flexible construction material that can be used for a wide range of applications. These include scaffolding around buildings during construction and structural elements of sustainable buildings.

Builders in China and the rest of Asia have used bamboo for centuries. You can see evidence of its use in artwork that dates back to the twelfth century, but it was a common building material for thousands of years before that.

It is very strong but lightweight, and you can transport and handle it easily. It is ideal for temporarily shoring buildings and providing a safe platform for construction workers operating at height.

But that’s not all that bamboo is good for. It is also widely used in building houses, bridges, and other structures.

Bamboo is a versatile material that can easily bend to almost any desired shape. For example, by treating freshly-cut bamboo with heat, it can be bent into archways or even bent round on itself to form a circle shape.

Bamboo is very fast growing, with some varieties adding 23 inches per day in the right conditions and reaching about 130 feet tall if left to grow to its full height.

It’s typically harvested in three to five years, much quicker than timber, which needs decades to grow. In addition, bamboo doesn’t need to be replanted and will regrow itself after harvesting.

Bamboo is a very sustainable building material, thanks partly to how quickly it regrows after harvesting.

It is also lighter than steel and many other building materials that serve a similar purpose, making transportation costs lower and associated carbon emissions much less.

In parts of the world where it has been a popular building material for centuries, it grows locally, reducing carbon emissions associated with transportation.

A series of platforms, walkways, and handrails using bamboo as the main structural sustainable building product.
Bamboo is a beautiful material to build with and brings character to any structure.

The construction industry is increasingly using bamboo fibers in new and innovative ways, such as in producing composite materials and as reinforcement in cement mortar and concrete. This innovative use of bamboo fiber is more environmentally friendly than thermoplastic composite materials and is a promising area for the future.

If you’d like to learn more about how bamboo can be used to make beautiful homes, why not read our article on bamboo homes?

2. Sheep’s Wool

A closeup of sheep's wool that can be used to insulate a home sustainably.
Sheep’s wool grows back every year, making it a sustainable resource that can be used to insulate your home. Its thermal properties are well-known, having been used for centuries by people to make woolen clothing.

Sheep’s wool has excellent insulation properties – just ask any sheep! They spend all winter on the hillside in freezing cold conditions and in the driving rain without catching their death of cold.

The fluffy fleeces that keep sheep warm in the field in the depths of winter are similar in structure to hair, but the diameter of each follicle is narrower. Wool is also more elastic and wavy than hair, helping to trap air and retain the warmth from the body to keep the animal warm.

People have known about the thermal properties of wool for centuries and have been knitting wooly sweaters to keep us nice and warm since history began. But now, more and more people are using sheep’s wool to insulate buildings, too.

The thermal conductivity of wool is similar to that of more commonly used insulating materials such as polystyrene. However, it is also non-flammable and structurally strong, making it well-suited to the insulation of a building.

Wool is sometimes combined with a polyester adhesive to form batts, much like traditional fiberglass batt insulation. They come in standard sizes, and workers can use them similarly to rockwool or other manufactured batt insulation.

Wool insulation is generally cheaper than fiberglass insulation, with some sources indicating a 50% saving when using wool instead of fiberglass.

The R-Values of these materials are very similar, with blown-in (loose fill) sheep’s wool achieving R 3.6 per inch and batts more like R 4.3 per inch. Blown-in fiberglass is R 2.2-2.7/inch, and fiberglass batts are about R 3.7/inch.

Sheep’s wool is a renewable resource because sheep grow a new fleece each year, starkly contrasting to polystyrene made from oil which is a finite resource.

Another advantage of sheep’s wool as insulation material for buildings is that it absorbs moisture from humid air, which it later releases into dry air. As a result, this property can help control indoor humidity levels and improve indoor air quality.

Sheep’s wool can also be recycled at the end of its service in keeping a house warm. In addition, it can be used as a reinforcement material in concrete and has other potentially promising uses, such as a carbon fiber precursor.

These recycling options further enhance its reputation as a sustainable building material.

3. Straw Bales

A straw bale house in the process of being built. The roof is on but the walls are unfinished, with the straw bales exposed.
Straw bale houses are exceptionally well-insulated thanks to the excellent thermal insulation provided by the bales. Image credit: Colin Rose, CC BY 2.0, via Wikimedia Commons

Straw bales are cuboid shapes made from the stubble left over after harvesting wheat and other cereal crops, such as barley, oats, and rice.

You might have seen them dotted around fields at harvest time because farmers cut the stubble and, using farm machinery, compress the freshly cut straw into a bale bound with twine to keep it all together.

The finished bales allow for easier handling of the straw, which farmers often sell or use for animal bedding on the farm or horse stables. However, using straw bales is gaining popularity among homebuilders keen to minimize their environmental footprint.

Straw bales are very good at providing insulation, and builders use them in construction by stacking them on top of each other to form the walls of a house.

A screenshot of a YouTube video showing the inside of a straw bale house under construction.
Strawbale constructions are a fairly sustainable building method, from sourcing to energy efficiency. FairCompanies.com and Kirsten Dirksen did a great documentary on a straw bale build.

The bales are like bricks of insulation, so it’s not surprising to discover that the R-Value they provide can be up to three times that of conventional insulation in a traditional home.

They are lightweight and easy to handle, so a house’s walls can be stacked over a weekend with a few people on hand to help out.

Workers stack each layer in a running bond, overlapping every other layer to increase stability. Finally, the finished wall is covered with mud to seal the surface and keep pests from taking up residence in the walls.

The bales can provide structural strength to a building, but most codes require a timber-built frame to support the roof, which is built on top of a traditional concrete foundation.

This type of building is very sustainable because the straw comes from a renewable source, a by-product of food production.

Once built, the high level of insulation saves energy and money on the heating and cooling bills, saving your wallet and the environment.

Compressed straw has many sustainability benefits, such as being 100 percent biodegradable and 100 percent recyclable. Once straw panels have reached the end of their life, they can be mulched down and used as compost in gardens or recycled back into panels, ready to be used again.

4. Reclaimed Wood

A reclaimed wooden parquet floor in closeup.
Reclaimed wooden parquet flooring can be a great way to add character to your home and be more sustainable at the same time. My neighbor’s floor looks amazing with his re-used oak flooring.

Wood is a common building material used in timber frames to provide structural support for many buildings. We also use it for finishings, floors, doors, and windows – it’s ubiquitous.

Ensuring such a commonly-used material is sourced sustainably goes a long way to improving the sustainability of the building process, which is where reclaimed wood can yield tremendous benefits.

Reclaimed wood is wood that has been used previously in other building projects.

Sometimes it is repurposed for the needs of the new project. For example, a large support beam could be milled to produce smaller sections for decorative purposes or even transformed into a bookcase or desk.

In other cases, an entire floor might be lifted and reinstalled in a different building.

Using recycled wood is one of the best ways to save trees and cut down the amount of lumber in landfills. You can obtain reclaimed wood from excavation companies, retired barns, home remodeling companies and contractors, shipping crates, and salvage yards.

Reclaimed wood is an excellent material for cabinetry, natural-looking flooring, exposed beams, and structural framing.

My neighbor took this approach during a renovation project on his home a few years ago. As a result, he now has a beautiful natural oak parquet floor in his living room, which would have cost a lot more and not been very eco-friendly if he’d used new timber.

Reclaimed wood, which doesn’t involve chopping down any more living trees, is more sustainable than using freshly-cut trees.

Trees are carbon sinks, which absorb carbon dioxide, removing it from the atmosphere where it would otherwise contribute to global warming. Therefore, keeping as many trees alive and growing as possible is vital in mitigating the effects of climate change.

An old rundown barn with faded red colored siding.
Re-using old wood is a very sustainable building practice, but not without its pitfalls.

Reclaimed wood is more sustainable than farm-grown wood, which normally comprises a single tree species. However, this monoculture is bad for biodiversity, and the nature of operations on these plantations can cause environmental problems if not managed appropriately.

Add to this the fact that reclaimed wood has a history of its own, which can be a great talking point for guests. For example, a wooden floor that previously served in a church brings more life to a building than brand-new wood that still smells of the sawmill.

Reclaiming many types of slow-growing wood is the only way to get hold of significant quantities. Longleaf Pine takes 200-400 years to mature and was used in the construction of warehouses and factories in the 18th and 19th Centuries, so there’s a decent supply of reclaimed Longleaf Pine available.

A few things to watch out for when using reclaimed wood include ensuring the supplier has cleaned the wood to remove any inappropriate finishes. Of particular concern is paint on wood in buildings built before 1978 because this might contain lead, which is harmful to human health and the environment.

Also, ensure you remove any nails, screws, or other items that could make working with the wood more difficult.

Another potential drawback of reclaimed or recycled wood is its possible lack of strength. Thus, make sure to assess the integrity of each piece and choose the one that’s most suitable for a specific project.

5. Recycled Wood (Engineered or Composite Wood)

A closeup of a sheet of oriented strand board (OSB) showing the individual strands that it comprises.
Oriented Strand board (OSB) uses offcuts and other wood waste to recycle it into a useful end product that is widely used and very cost-effective.

Recycled wood differs from reclaimed wood because you don’t simply dismantle and refurbish it. Instead, it is processed more heavily, often chipped into small pieces before being formed into usable sheets, as is the case for chipboard (also known as particle board).

The government of California estimates that construction and demolition waste make up about 28% of the solid waste generated in the state. About one-fourth of that is estimated to be wood waste, although the proportion you can reuse as lumber will be much smaller.

Much of the waste wood generated by construction activities is from off-cuts and sawdust, which cannot be reclaimed and reused as lumber.

Instead, this kind of fragmented wood waste can be processed and recycled into building materials such as engineered wood like oriented strand board (OSB).

Modern construction techniques seek to minimize waste by designing buildings around standard timber sizes and using prefabricated off-site panels.

But you should segregate wood waste generated on-site to ensure a clean waste stream that recycling facilities can use to make products that would otherwise end up in a landfill. In addition, on-site segregation ensures that more waste wood is recycled through the system into engineered wood of one type or another.

Engineered wood is made by taking waste wood of the appropriate particle size and binding it together with resin or another binder.

Sometimes green wood that is too thin to be used on its own is used in the manufacture of engineered wood, combining many smaller pieces into a composite unit that is much stronger.

Engineered (or composite) wood includes the following.

  • Particle board: Particle board (aka low-density fiberboard or chipboard) is made from wood chips, sawdust, manmade resin, or other binders, which are pressed and pushed through a die in a process known as extrusion.
  • Medium Density Fiberboard: MDF is similar to particle board but is made with wood fibers instead of sawdust particles, which are bound together with resin under heat and pressure. It is denser and heavier than particle board and even denser than plywood.
  • Hardboard: Hardboard (also called high-density fiberboard) is made from wood waste processed to make pulped wood fibers before being compressed into sheets without glue.
  • Blockboard: Blockboard (sometimes called laminated wood board) is made from strips of natural wood battens sandwiched between two layers of plywood.
  • Plywood: Plywood is made from multiple layers of wood veneer glued together. Each layer’s grain is oriented at a right angle to adjacent layers, increasing the plywood’s strength.
  • Oriented Strand Board (OSB): OSB is made from multiple layers of shredded wood strips bound together with wax and resin adhesives. The layers are cross-oriented to enhance the strength of the final product.
  • Steam-pressed scrim lumber: Scrim lumber uses small diameter logs unsuitable for heavy structural uses and converts them into engineered lumber or sheets by shredding them into long strands and binding them together with adhesive.
  • Glued laminated timber: Glue laminated timber (glulam) is made from layers of lumber arranged with all the grains running along the length of the product and bound together with adhesive.
  • Cross-Laminated Timber (CLT): CLT is made from multiple glued layers of lumber boards stacked with the grain of each successive layer running at 90° to the adjacent layers. This cross-lamination creates a very solid wood panel.

Many of these engineered wood types offer uses for wood that would otherwise be discarded, minimizing waste and improving the sustainability of the construction industry.

Ensuring the resins and adhesives used in their manufacture are eco-friendly further enhances their green credentials.

6. Rammed Earth

A rammed earth wall with the different layers clearly visible.
Rammed earth has a pleasing aesthetic thanks to the layering of the compacted earth used in its construction.

Rammed earth edifices are made using subsoil, normally obtained from the construction site.

The technique has been around for millennia and is seeing something of a resurgence now because it is a more sustainable approach to construction than many of the standard modern approaches, many of which are far more energy intensive.

Rammed earth can form floors, walls, and foundations. It requires using subsoil with the right geological materials, typically a mixture of silt, clay, sand, and gravel.

The subsoil is mixed with water to make it damp enough to work with, and a stabilizer may be added if required. Cement can be used as a stabilizer, but lime has been used or even animal blood.

Once mixed together, the subsoil and stabilizer mixture is poured into a frame or mold, known as formwork, which holds it in place until it is set.

The mixture is poured in thin layers of around four to ten inches, which are compacted with a hand-held tool called a ramming pole, although these days, it is more common for pneumatic tampers to be used, which speed up the process.

After compacting each layer, the next layer is poured, and the process is repeated until the wall or slab reaches the desired height.

A tan wall made out of rammed earth.
Rammed earth has been used in construction for thousands of years and still has much to offer despite the advent of modern building practices.

Rammed earth is very strong and durable and can meet building regulations for strength, insulation, water resistance, etc. Evidence of its durability can be seen in historic structures that are still standing 2,000 years after they were originally built.

Rammed earth is a very sustainable building material because the raw materials can be sourced locally, often on the site itself. As a result, the energy requirements for handling and forming rammed earth edifices are very low, and very little waste is produced.

These days, rammed earth can be seen in luxury homes creating durable and dramatic walls which look very much like sedimentary rock. In addition, rammed earth walls or floors can be used as thermal storage. This allows the sun to warm them during the day and gradually release the warmth in the cool evenings.

It’s worth investigating whether rammed earth is the right choice for your next sustainable building project.

7. Earthbag

Earthbag home under construction. It is being built in a dome shape with small openings at the front.
Earth homes are very sustainable thanks to the use of natural materials with low embodied energy that are typically available on the construction site itself. Image credit: DVIDSHUB, CC BY 2.0, via Wikimedia Commons

Earthbag construction is a very sustainable method of house building that entails stacking bags filled with earth, generally dug up from the construction site itself.

The approach is simple and can be easily learned by novices, although you must take care to follow the process correctly to avoid problems down the line.

Polypropylene bags are a good choice for earthbag buildings because they are fire-resistant and waterproof. You fill the bags with earth taken from the site, and the best mix contains a good mix of dirt, sand, and clay.

The filled bags are laid next to each other, sometimes on a concrete foundation and sometimes on a simple rubble trench. Each successive course of bags is laid in an overlapping manner and held in place with barbed wire that runs between each course.

Sometimes twine is also used to hold layers together, and it’s possible to reinforce corners by hammering rebar through the layers of bags.

The upper courses can be narrower in diameter to form a dome, which avoids making a separate roof. However, make a timber-framed roof on top of the last course of bags if you want.

Modern building materials often use a lot of energy in their manufacture and must be transported miles from the factory to the construction site. This high embodied energy makes for a pretty hefty carbon footprint, not to mention the harmful chemicals often used to make or maintain them.

In contrast, earthbag homes have a very low carbon footprint because the raw materials (mainly earth) require no processing and minimal handling. If you can get enough earth from the construction site, there is no fuel used in the transportation of materials save for the bags and barbed wire, which are very lightweight.

The completed walls are finished with plaster, and you can paint them in your choice of color. The final R-value of an earthbag wall is R-26 to R-30, which is in the range of a straw bale wall. This is a very high level of insulation, which makes the completed building very eco-friendly, too.

8. Cob

A cob house built in Wales, UK. The walls are round and have colorful decorations embedded.
Cob is a very versatile material to build with, allowing walls to be molded into any shape and windows added as you go. You can even add decorative flourishes embedded straight into the wall. Image credit: Lizzie Wynn, Project Manager – Bwyd Bendigedig Port / Incredible Edible Porthmadog, CC BY-SA 4.0, via Wikimedia Commons

Cob uses subsoil mixed with straw and clay to make buildings with thick walls laid in layers to form a monolithic structure.

There’s a saying that a good cob house needs “a good hat and a good pair of boots” to ensure it stands up to the weather over time.

The “boots” are a metaphor for the foundation of the building, which can be a well-drained rubble trench, bricks, stone, or poured concrete.

Above the foundation, a stem wall (also called the plinth) raises the cob off the ground. It separates the cob structure from the ground, avoiding saturation with water that can lead to structural issues and even collapse.

The “hat” of the house is the roof, and cob houses generally have a large overhang, which helps to protect the walls beneath from erosion caused by rain. They are also an attractive design feature that adds character to cob homes.

The subsoil for the cob mix is generally taken from the construction site if it is of the right composition. In many parts of the world, you can take suitable soil from 15-24 inches below ground level.

A pair of woman's dirty hands holding some dirt and cob material.
Only use cob if you don’t mind getting some dirt under your fingernails.

The best soil to use must have a clay content of between 10-25% and include well-graded aggregates, including fine silts to coarse gravel, without too many larger stones, which can cause cracking in the final structure.

You make a typical cob mix from four parts subsoil, three parts straw, and one part water. The mixture is prepared by laying down a layer of straw, wetting it with water, covering it with a layer of subsoil, and then adding a final layer of straw. The whole lot is then mixed together by “treading,” traditionally done by teams of workers and animals.

The cob is laid in 3-6 inch thick layers to form walls that are typically 3 feet thick and up to two stories high. Many finish the walls with lime wash, which protects them from the elements and gives them a pleasing appearance.

Cob houses are sustainable because they use locally-sourced materials requiring minimal energy. A backhoe loader might help to speed things up on site but is not a large source of carbon emissions compared to standard-built homes.

Cob homes also have a lot of thermal mass, which evens out diurnal variations in temperature, in addition to providing good insulation, which minimizes carbon emissions from heating and cooling.

They also absorb and release moisture, helping to control humidity levels and improve indoor air quality.

9. Adobe

An elegant adobe wall made from adobe bricks and cement. There are rows of stones set into the mud mortar.
Adobe walls can have a very good-looking appearance and are very sustainable.

Adobe is Spanish for “mudbrick,” and buildings have been built using this material for thousands of years, with evidence of its use in countries worldwide.

The bricks are made with sand, clay, and organic material (typically straw). The bricks are unfired, saving the energy you would need to heat a kiln, as is the case for standard house bricks.

The first step in making the adobe bricks is to run the soil through a screen to eliminate larger lumps of aggregate. If the soil on the construction site has the right particle size distribution, this cuts down on the work required to prepare the materials.

If your soil is too sandy or contains too much clay, you can adjust this by adding more sand or clay-rich soil as required.

I’ve seen adobe bricks made in New Mexico using local soil and a process that uses 3-gallon buckets to measure out the various ingredients. That process uses four buckets of water, two buckets of straw, seven buckets of clay-rich soil, and seven buckets of coarse sand.

You mix the materials in a metal trough and then pour the mixture into wooden forms, which serve as molds for the bricks.

You then leave the bricks to dry for a day before removing them from the wooden forms and standing them on their sides to dry further. After air-drying for about a week, they are ready for use. The bricks are used to build the walls of houses and are very easy to work with.

They are held together by mud mortar, although in many areas, code requires the first course of adobe bricks to be held in position by cement mortar. You must also fully stabilize the bricks to prevent them from dissolving if water leaks into the structure.

Adobe houses are sustainable because they are constructed using local materials and have low embodied energy.

The thick walls have high thermal mass, which helps stabilize the temperature within the building. This thermal mass reduces heating and cooling costs or, with the right design and suitable climate, eliminates them altogether.

10. Recycled Plastic

A man working on a wall of multicolored, recycled plastic bricks.
The recycled plastic brick developed by a team in the Netherlands can be used worldwide for washing facilities and homeless shelters. Image credit: Recycle Rebuild open-source: recycled brick.

Plastic waste is a real problem, with an estimated 13 million tonnes of plastic waste entering the world’s oceans every year.

Inappropriately managed plastic waste harms the health of ecosystems, people, and economies. The UN warns that the problem is getting worse, with 12 billion tonnes of plastic waste expected to be in the natural environment or landfills by the middle of the century.

Anything we can do to reduce this colossal amount of plastic waste is a good thing. The construction industry is already making better use of waste plastic in its supply chains.

Several companies are using a carbon-neutral, non-toxic manufacturing process to make construction materials out of recycled plastics, reusing old material results in a 95 percent decrease in greenhouse gas emissions as compared to concrete blocks.

Recycled plastic building materials are a sustainable option because they repurpose plastic waste and turn it into a functional product used in construction.

A mix of virgin and recycled plastic can be used to create polymeric timbers, which can be used to make picnic tables, fences, and other similar structures.

In addition, plastic from two-liter bottles can be spun into fiber to produce carpets. Last but not least, reused plastic can be used to make products like PVC windows, PVC manholes, cable pipes, floors, and roofs.

Plastic does not corrode or degrade quickly and is water resistant, making it an ideal building material. In addition, it provides thermal and electrical insulation and will last a long time.

On the downside, it is not as strong as many commonly used building materials, so it can’t easily be used for structural or weight-bearing purposes. It also doesn’t hold screws or nails well.

Waste plastic can be mixed with other materials to overcome these strength-related limitations and allow its use in situations where strength is essential.

In India, an enterprising company mixes recycled plastic with foundry sand to form silica plastic blocks.

Using foundry sand and plastic waste in a single product is a double whammy in helping the environment because foundry dust is also a waste material and causes heavy metal pollution of the soil and water environment if left in disposal heaps.

Another innovative organization, this time based in the Netherlands, has designed an “open source recycled brick.” The brick looks like an oversized Lego brick made from 100% recycled plastic.

It is hollow and doesn’t need mortar thanks to the tight interlocking teeth, allowing structures to be built very quickly. Its creators envisage the brick being used worldwide for cheap structures like washing facilities and homeless shelters.

Recycled plastic is also being used as an experimental concrete additive, with promising results showing irradiated plastic increases concrete strength by up to 15% when used as an additive.

Recycled plastic can make many building materials, such as roof tiles, insulation, and even structural lumber.

The more plastic diverted from landfill or prevented from being dumped in the environment, the better. This is a massive opportunity for the construction industry to make its supply chain more environmentally friendly.

11. Cork

A house made entirely from cork and held together by gravity. There are several triangular domes with skylights at the top.
This house is made entirely from cork. However, cork can be used in any house to provide an aesthetically pleasing and warm floor or wall. Image credit: Dezeen

Portugal is one of the biggest producers of cork in the world, with hundreds of thousands of hectares of cork in production.

Cork is the bark of the Cork Oak Tree and can be harvested every nine years by peeling off the outer bark with a special cork axe. The cork oak tree regenerates its outer layer every nine years, making it a renewable resource.

A tree with cork stripped away from its trunk, exposing the raw wood underneath.
Cork will regrow readily and can be harvested again in about nine years’ time.

Once stripped from the trees, the harvested cork is left out in the open for six months to weather, improving the cork’s quality.

Cork has a long history in the construction industry, with evidence of its use for roof sheeting in Roman times. It was also one of the first materials used as a rigid insulation board.

Architects use cork for its sustainability credentials and to create engaging sensory experiences in their homes. Cork has a visually appealing texture and is warm to the touch, making it an exciting material to build with.

You don’t need to be a wine connoisseur to know that cork plays a big role in the wine industry, being used to seal wine bottles.

However, you might not know how wasteful this process is, with only 25% of the cork material used in the corks destined for wine bottles. This inefficient use of the material means that 75% of the cork is left over and goes to waste.

The waste cork is granulated and then dry-steamed so that the granules bond together in their natural juices, making it a pure, plant-based product.

Cork is very lightweight and has low permeability to liquids and gases, so you can build a very airtight home using it. It is also a fantastic thermal insulator, making it a great material for minimizing your heating and cooling requirements.

Add to this the fact that it uses a recycled waste product from the manufacture of cork stoppers for wine bottles, and you have a very sustainable material that can be used in your next building project.

Check out this award-winning home built entirely from cork.

The first house entirely built with cork is in Eton in the UK. The walls are built with interlocking blocks of cork that rely on gravity to keep everything in place. Check out the video featuring the architect who designed it and who also now lives in this amazing house. https://youtu.be/divQz511Xvc

12. Recycled Steel

Recycled steel rebar stacked together horizontally.
Rebar is used to reinforce concrete and improve its strength. Sourcing recycled stell for this purpose will reduce the environmental footprint of your building project.

Steel is an incredibly strong and durable material favored by the construction industry for its load-bearing properties and ease of handling.

It is used in structural sections to provide frames for many types of buildings, reinforcing bars in concrete, cladding outside structures, and fixtures and fittings inside a building. It is a very versatile construction material.

Steel contains low carbon levels (0.12-2.0%), although sometimes the iron is alloyed with other materials to enhance its properties for particular uses. For example, stainless steel, corrosion-resistant and long-lasting, is alloyed with chromium and used widely in commercial kitchens.

The type of steel most used in construction is plain carbon steel, also known as mild steel.

The production processes used in steel manufacture are very energy-intensive, with the steel industry making up six percent of the energy used across the whole manufacturing sector in the US.

Many of the steel manufacturing processes rely on coal, a non-renewable natural resource responsible for the emission of greenhouse gases into the atmosphere, causing global warming.

Given the high energy requirements for steel production, it is very beneficial to use reclaimed or recycled steel whenever possible.

Steel can be reused many times, and using bolts to attach individual steel beams allows for easy disassembly for reuse at the end of a building’s life.

Steel also lends itself to recycling, where it is melted down in a furnace and used to make new items, such as car fenders, bicycle frames, and many other everyday objects.

Add to this the fact that it is environmentally inert and does not cause pollution when in direct contact with the environment.

You can see that reclaimed or recycled steel is an environmentally-friendly building material worthy of consideration in your next building project.

13. Precast Concrete

Precast concrete slabs stacked on hardstanding and separated by pieces of wood.
Precast concrete often has a smaller carbon footprint than on-site concrete and results in less wastage.

Concrete of any type has a fairly significant carbon footprint, so you might be surprised to see it on this list.

However, sometimes the project you’re working on requires it. In those circumstances, you should consider precast concrete, which is often a better option in terms of the environment.

Concrete is one of the most common building materials in the world and is used everywhere, from houses to office blocks and car parks to football stadia.

It has incredible compressive strength and can take on any shape you can think of, which makes it extremely versatile.

The manufacture of cement, a key ingredient of concrete, is where most of the carbon footprint comes from, with each tonne releasing 600 kg of carbon dioxide during its production.

Anything we can do to reduce these emissions can significantly affect the final product’s sustainability. And that’s where using precast concrete can make a difference.

Precast concrete simply means concrete that has been formed using a mold in a factory and travels by truck to the site, where it is lifted into place.

The main environmental advantages of precast concrete come down to efficiencies of materials usage.

Because it is made in a factory under controlled conditions, it produces less waste. There is no need for on-site formwork, and the molds in the factory can be reused thousands of times, helping to make the process more efficient and less wasteful.

The controlled conditions of the factory also ensure that bad weather or unexpected frosts cannot impact the curing process, avoiding rework and wastage.

When demolition crews take down concrete buildings, the concrete can be recycled and is often broken up and used for the foundations of new buildings. This helps to improve the sustainability of concrete, ensuring that it remains higher up the waste hierarchy.

14. AshCrete

An ashcrete block, which is similar in appearance to a gray concrete block.
Ashcrete is more sustainable and more resistant to sulfate attack than concrete. It also uses less water in production. Image credit: Ashcrete Techologies.

AshCrete is concrete that aims to be more sustainable than varieties that use only standard Portland cement. It uses ash from coal-fired power stations and smelting processes to enhance its strength, reduce costs, and lower the amount of embodied carbon it contains.

It was invented by Pliny Fisk III, part of the husband-and-wife team in charge of the Center for Maximum Potential Building Systems, and an associate professor at Texas A&M’s College of Architecture.

Fisk is an expert in sustainability issues, and AshCrete tackles the twin sustainability problems associated with concrete. Namely the large carbon emissions of the concrete manufacturing process and the disposal of the residue from power generation at coal-fired power plants.

It is common practice to add Supplementary Cementitious Materials (SCMs) to concrete during production.

Fly ash is a popular SCM. It has a smaller particle size than Portland cement, which means it fills more of the voids in concrete, increasing the strength and decreasing the permeability of the final product.

Fly ash contains toxic metals such as aluminum, cadmium, arsenic, and mercury, which can harm human health and the environment. However, the leaching of metals from the fly ash decreases significantly when bound in the concrete.

Leachability testing and careful assessment of AshCrete’s suitability for the intended use case are important to avoid potential risks to human and environmental health.

The amount of fly ash to be added to concrete depends on the project’s specific requirements but historically ranged between 15% and 25%.

More recent studies have shown that much higher proportions (40%-60%) can produce concrete with good durability and mechanical properties suitable for use in applications requiring structural strength.

Advantages of AshCrete also include a reduction in the amount of water required in its production compared with standard concrete and improved long-term strength development.

Concrete incorporating high proportions of fly ash is more resistant to sulfate attack, which is desirable in high-sulfate groundwater or soil conditions.

Incorporating fly ash decreases production costs, diverts material from landfills, and reduces the amount of virgin aggregate used, which makes AshCrete more sustainable than standard concrete using only Portland cement.

15. Ferrock

Ferrock paving slabs lain on sand.
Ferrock can be used to make paving slab, building blocks, or any other building material where concrete would normally be used. Image credit: Material Transformations – UMN

Invented by accident by David Stone in 2002 during his time as a Ph.D. student at the University of Arizona, Ferrock is a more sustainable alternative to standard concrete that uses waste steel dust as one of its key raw materials.

The best way to describe ferrock is as a largely iron-rich ferrous rock. It’s made with recycled material such as waste steel dust and silica from ground-up glass. When it comes to building homes, ferrock is generally used as a substitute for cement.

The best thing about ferrock is that it traps and absorbs carbon dioxide as part of its drying and hardening process.

Ferrock is about five times stronger than concrete made with Portland cement and is excellent in applications where temperatures exceed 1,000 °F.

It is also well-suited to applications in marine environments because it is chemically inactive. In fact, Ferrock increases in strength when exposed to saltwater.

Another advantage Ferrock has over ordinary cement is that it sets faster. Normal concrete goes off in around 1-2 days, reaching its full strength after about a month. Ferrock, on the other hand, completely hardens in just one week.

Approved for use in walls, sidewalks, slabs, and pavers, Ferrock has a small foothold in the market. However, it doesn’t have approval for use in bigger structures, roads, and other important infrastructure. Ferrock’s lack of official approvals is partly because it is relatively new, and its life cycle is not fully understood.

It is made from 95% recycled materials, including waste steel dust (60%), fly ash (20%), silica fume (8%), limestone (10%), and oxalic acid (2%). In addition, it mainly uses waste products from other manufacturing processes, making it much more sustainable than concrete made with ordinary Portland cement.

In addition to recycling various waste streams from industry, Ferrock is also carbon negative, meaning it is a net absorber of carbon dioxide over its lifetime.

Compare this to regular cement, the production of which emits huge amounts of CO2 into the atmosphere and accounts for 8% of total carbon dioxide emissions. The benefits of Ferrock in terms of CO2 emissions are apparent.

16. Hempcrete

A house made from hempcrete. It has two stories and solar panels on the roof.
This house built in the Highlands has been made from hempcrete. The hempcrete gives the walls very high insulation properties. Image credit: Tommygibbons46, CC BY-SA 4.0, via Wikimedia Commons

Hempcrete is a bio-composite comprising a mixture of water, lime binder, and the wood-like core of the stems of the hemp plant.

The hemp component of hempcrete has the appearance of wood chips, almost like you’d expect to see as a raw material for OSB or chipboard. The lime binder is a specialized blend of limestone, which is a natural cement made from limestone.

The ingredients are mixed in batches, often in a special, industrial-sized mixer on the construction site. The mixed hempcrete then goes into wooden forms that hold the mixture in position as it is leveled and tamped down to create the wall.

The walls are built up one layer at a time, pouring mixed hempcrete into the wooden forms and tamping it down as the job proceeds.

You firmly tamp down the edges of each layer next to the wooden forms, leaving the middle of the walls looser. This looser packing in the middle ensures sufficient air is trapped within the wall to provide the high insulation values that hempcrete can provide.

This type of construction gives R-values of R-2.5 to R-3 per inch, which is very insulating, easily providing an R-30 wall if built 10 inches thick, which is impressive.

Hempcrete is not load-bearing, so a wooden frame is typically included in the wall. Building this frame in the middle of the wall avoids cold bridging effects that would otherwise come from timbers extending through the walls.

Once set, the organic matter in the hempcrete reacts with the low-alkalinity lime binder, which renders it inert and prevents it from decaying or attracting mold growth. Instead of decaying like plant matter usually does, the hemp in the hempcrete behaves more like stone, essentially inert.

A damp proof course is essential to prevent moisture from rising into the hempcrete walls, which could cause damage over time.

Hempcrete is sustainable because it contains mainly hemp plants, a fast-growing and renewable crop. The hemp plants also absorb CO2 as they grow, sequestering it in the hempcrete.

In addition, as the hempcrete cures, it absorbs even more CO2, making it carbon negative and very eco-friendly.

Once you build these walls, they serve as a very effective insulation layer, which keeps HVAC costs down in the house.

Hempcrete has a relatively high thermal mass. Hence, it evens out diurnal variations in temperature, absorbing heat during the day and releasing it overnight, making for a very comfortable living space.

The finished hemp walls are also fireproof, which is a fantastic safety benefit.

Not only does hempcrete contain very low embodied carbon, but it also helps to conserve energy by providing excellent thermal insulation and minimizing heating and cooling requirements. This makes it one of the most sustainable building materials you can use.

17. Oriented Structural Straw Board (OSSB)

Sample shots of oriented structural straw board (OSSB). The randomly oriented straw fibers are clearly visible.
The random orientation of the straw fibers in OSSB help to give it its structural strength. Image credit: istraw

Oriented Structural Straw Board (OSSB) is an engineered board made from agricultural residue left behind after crops such as wheat, rice, and barley.

Not to be confused with straw bale construction, which uses the intact bales of straw to form walls for buildings, OSSB is made by processing the straw to remove very fine particles and shredding the longer strands of straw to cut them to the correct length for the next stage of the process.

The straw pieces pass through a press, compressing the straw fibers together to form them into a board shape.

Heat is applied at this process stage to raise the straw’s temperature to around 400°F. The high temperature causes the straw to release lignin, which binds the fibers together, although some processes use an adhesive to bind everything together.

Finally, the straw board is rolled and faced with paper, creating a smooth board cut to standard lengths ready for sale.

The finished board is suitable for internal and external walls and can bear loads thanks to its high structural strength. It is also capable of holding nails and other fixings very well.

The resin used in manufacturing OSSB doesn’t contain formaldehyde and does not emit VOCs, which helps safeguard the indoor air quality of the buildings it is used in.

The straw board has very low embodied energy and uses a by-product of food crops as its main raw material that would otherwise have gone to waste. This makes it a very environmentally friendly, sustainable building material.

18. Timbercrete

A modern timbercrete house with large windows and a wooden porch.
A timbercrete house in Aukland with large windows and a wooden porch. Image courtesy of Houzz . Photo by Specky’s WorkshopDiscover house exterior design inspiration

Invented by Australian Peter Collier, he first used Timbercrete to construct his own house in 1995.

Collier, a potter, sculptor, artist, and ceramic technician was looking for a cheap material with excellent structural and aesthetic qualities. But, as an artist, he also wanted to create unique and new material.

Timbercrete has good load-bearing capacity, and the manufacturing process can be modified slightly to ensure the specific engineering needs of different projects can be met.

It is bulletproof, lightweight, and can be screwed or nailed without pre-drilling, making it popular with workers.

It has good thermal properties, with the standard blocks achieving an R-value of R-1 per 25 mm thickness and the “super insulator block” reaching R-4. It also has workable thermal mass, which helps to even out temperature extremes, keeping the indoor space comfortable around the clock.

These well-balanced thermal properties outperform many traditional building materials and allow Timbercrete homes to have a single skin, which greatly simplifies construction and means separate wall insulation, vapor barrier, or drywall are not required.

Timbercrete is made from timber waste, sand, cement, binders, and a few other materials, which, when combined, can be molded into any desired shape. In addition, the blocks do not require firing, which keeps embodied energy low, reducing carbon emissions.

No trees are felled to provide wood specifically for Timbercrete because all of the wood material comes from waste produced at sawmills, discarded wooden pallets, and plantation waste.

Providing a route for this waste material to be used rather than simply disposed of helps create a circular economy, which is more sustainable and better for the planet.

One of the innovations I particularly like is the creation of Timbercrete’s cleverly designed “service blocks,” which have channels and cutaways that allow services such as plumbing and electrical lines to run inside the wall.

The combination of Timbercrete’s low embodied energy, recycled raw materials, and excellent thermal insulation makes it a very sustainable building material.

19. Recycled Rubber

Recycled rubber flooring being laid on an interior floor.
Recycled rubber is a great material for use as flooring. It is popular in gyms because of its shock-absorbing and sound-deadening properties.

Rubber is used throughout the modern world and was first used in the Mesoamerican region that makes up modern-day Central America. It was introduced to Europe in the 1700s, where one of its first uses was as the “rubber” used to remove pencil marks from paper.

Natural rubber comes from the milky white colloidal material that oozes out of plants such as dandelion and rubber trees.

Demand has long since outstripped the production capacity of natural rubber, and these days, synthetic rubber is produced on an industrial scale using petroleum by-products.

Rubber is very useful in the construction industry for flooring, waterproof coatings, shingles, insulation, adhesives, mulch for gardens, and impact-absorbing mats in playgrounds and gyms. It is a very versatile material.

Rubber has excellent durability, water resistance, and other properties that make it useful for buildings. However, it has a large carbon footprint, with estimates of carbon emissions in rubber products producing between 1-1.5 tons of CO2 equivalent per ton of product, which is even higher than cement at 0.93.

Using recycled rubber in manufacturing helps lower rubber production’s carbon footprint and minimizes the use of virgin materials, making it more sustainable.

Recycled rubber products are available from several manufacturers, including flooring from recycled tires by Itstru Technology, Ecore, and roofing materials from Euroshield.

20. Newspaper Wood

A closeup of newspaper wood showing the grain-like effect that the ink showing at the edges of each layer produces.
Newspaper wood is a fascinating material in terms of design, thanks to its appearance, which is a bit like natural wood but subtly different. The grain visible in newspaper wood comes from the exposed ink at the edge of each layer of paper.
Image Credit: The New Motor

Everybody knows that newspaper comes from wood, but until Dutch designer Mieke Meijer developed newspaper wood in 2003, the reverse of this process was not possible.

Before newspaper wood, you could only turn paper collected for recycling into more paper and cardboard.

The creation of newspaper wood takes a different approach. Instead of sorting, pulping, de-inking, and then processing it back into paper, the paper is reconstituted into a solid block.

The paper is sourced locally and comprises mainly undistributed newspapers – literally yesterday’s news.

The old newspaper is wound around a drum and glued together in a process that creates a newspaper “log,” complete with grains.

When the glued log has set, the material can be cut and sanded in the same way as normal wood, exposing the edges of the layers of newsprint in a way that resembles the grain of natural wood.

Although newspaper wood resembles standard wood, it is not as strong and is unsuitable for heavy structural parts of a building. However, it is suitable for building furniture and decorative finishes, such as wood cladding, skirting boards, and the like.

It can also be a veneer, which can be applied to more robust base materials that can then be used in more heavy-duty applications.

Newspaper wood using locally sourced waste paper cuts down on transportation costs and fuel usage, minimizing the carbon footprint of this upcycled material, which adds design interest to any project.

Finding alternative uses for wastepaper helps to promote the circular economy and earns newspaper wood the right to call itself sustainable.

21. Plant-Based Polyurethane Rigid Foam

A builder applying plant-based rigid polyurethane foam to a blockwork wall.
Plant-based polyurethane rigid foam insulation is a more sustainable alternative to synthetic, petrochemical-based foams. It is also better at insulating your home, so it makes great sense to use it.

Rigid foam insulation is widely used in construction to insulate buildings, prevent air leaks, and control moisture.

It has excellent thermal efficiency, with R-values between R-3.6 and R-8 per inch of thickness, depending on the type of foam in use.

Many foams available on the market today are made from oil-based petrochemicals. These mineral oil-based foams cause environmental concern because they are derived from non-renewable fossil sources, and their production requires large amounts of energy.

However, the pressure to address the global climate and biodiversity crises has encouraged a shift from petroleum-based polyols to plant-based polyols like lignin.

These plant-based raw materials can make polyurethane foams with a smaller environmental impact and lower carbon emissions.

Another approach is to use natural fiber, such as jute or sisal, to reinforce the foam matrix.

Polyurethane foams made using such ingredients have higher thermal insulation properties than petroleum-based foams.

This makes the production of the foam boards more environmentally friendly and enhances the finished product’s performance, helping to cut down on heating and cooling requirements and lowering the carbon footprints of the homes.

22. K-Briq

A small stack of multi-colored K-Briqs on a table in a lab.
The K-Briq is a fantastic example of the circular economy working as it should. These bricks are made from construction waste and are sent back out to site to build new buildings. Image courtesy of KENOTEQ

The K-Briq was developed in a collaboration between Kenoteq, Construction Scotland Innovation Centre (now BE-ST), Heriot-Watt University, and Hamilton Waste Recycling. It aims to be a simple, environmentally-friendly, and innovative product that helps to reduce the amount of construction waste going to landfill.

It contains over 90% recycled demolition and construction waste. Its raw materials are inert, meaning they do not leach pollutants when they come into contact with water and, therefore, would not pose a severe risk of pollution to the environment.

These inert materials are blended with some waste plasterboard and proprietary ingredients. The mixture is then pressed together under high pressure to form the K-Briq.

The K-Briq is a charming example of the circular economy because it uses construction and demolition waste, which is processed to turn back into a building product, closing the loop.

According to BE-ST, the K-Briq is more robust, lighter, and lasts longer than a traditional clay-fired brick costing less to manufacture.

Since the K-Briq is not fired in a kiln like a traditional house brick must be during manufacture, the K-Briq has much lower embodied carbon, making it a far more sustainable alternative.

The K-Briq also uses no cement, the manufacture of which is very carbon-intensive, further enhancing its environmental credentials.

The K-Briq has one-tenth of the emissions caused by a standard brick, which, combined with the fact that it is made from 90% recycled material, makes it a very sustainable option for your next building project.

23. Mycelium

Mycelium insulation panels made by BIOHM. They are a marbled brown and white in color with a natural appearance.
The mycelium insulation panels made by BIOHM are a sustainable, renewable alternative to other types of insulation rigid foam boards that have much higher embodied carbon. Image courtesy of BIOHM.

Interest in mycelium as a building material has increased in recent years thanks to its sustainability and potential uses.

Mycelium is the name given to the structure of root-like filaments that branch out from fungal spores, which the fungus uses to obtain nutrients. These filaments are surprisingly strong and durable, which are valuable properties required in building materials.

You can mix mycelium with organic substrates, such as agricultural waste like hemp hurds, oat hulls, wood chips, or cotton burrs, as the first step in manufacturing.

The mixture is then placed into molds and left for a few days in a controlled environment, which allows the mycelium to grow, quickly filling the void space in the mixture.

After about a week, the items are popped out of the molds and allowed to grow for a couple more days, forming a smooth, velvet-textured surface around their outsides.

After the production’s growing phase, the items go into a kiln, where the heat dries out the material, killing the fungal spores and ceasing the growth process.

The end material lasts three decades, provided it remains in dry, temperature-controlled environments. This is probably its biggest current drawback as far as its use in the construction industry is concerned because most applications require longer lifespans than this.

However, it is acceptable for some applications, such as temporary housing or exhibitions. Mycelium serves as a packaging material because that application doesn’t require as long a service life as in construction.

It is also used to produce insulation panels, acoustic sound-proofing products, and floorings, for which the relatively short lifespan might be less of an issue.

Improvements in the production process will improve the lifespan of these products, and there is already work looking at improving the strength of mycelium bricks and panels that might lead to their use in structural applications in the future.

Two mycelium mushrooms growing from the forest floor.
Mycelium is the vegetative part of a fungus that runs below the ground. It is a solid, environmental-friendly material that’s resistant to water, fire, and mold.

For now, though, mycelium is an experimental material for building.

Its sustainability advantages include being non-toxic, water resistant, fire retardant, and having low embodied energy.

At the end of its life, it will compost in soil within 45 days, provided it is shredded into 1cm3 pieces. The substrate is often from agricultural waste, the reuse of which is another plus in terms of sustainability.

Hopefully, we’ll see this fascinating, sustainable material used more widely in the future.

24. Solar Shingles

A screenshot taken from Austin Flack's YouTube video on Tesla solar roof tiles. It shows an aerial view of a single-story house with the shingles installed.
Austin Flack did an awesome one year review video on Youtube, covering basically everything you’d want to know about the Tesla solar roof tile system.

Solar roof shingles are small, custom shingles designed to blend in seamlessly with conventional roof tiles.

Such shingles aren’t just aesthetically appealing; they function as durable roof tiles and solar panels. Thus, your roof will stay safe from the elements while still absorbing sunlight for energy consumption.

One option that you can consider is Tesla Solar Tiles.

25. Smart Glass

During winter, warm sunlight flowing through the window can seem to be the best thing in the world. However, during summers, the same sunlight can feel uncomfortable, invasive, and harsh. Plus, it can also increase your electricity bills due to heavy dependence on air conditioning.

Smart Glass windows offer a great solution to this problem. Smart windows or smart glass refers to glazing or glass whose light transmission properties change depending on heat or light is applied. In simple words, the glass becomes translucent during the summer to block certain wavelengths of the sun and transparent during winter to allow the warm rays to flow inside.

A traditional-looking tan commercial building with dark tinted glass in the windows.
Smart glass allows the sun’s warmth to enter the building during the winter but reflects it during the summer.

Windows that can change the glass translucency can result in annual cost savings in cooling and heating and avoid the hassle and cost of installing blinds or light screens. With smart glass, you can even prevent fabric fading as it blocks almost 99 percent of harmful ultraviolet rays.

26. Plant-Based Polyurethane Rigid Foam

Plant-based rigid foam is usually used as furniture material and insulation. It is made with bamboo, hemp, and kelp, making it highly resistant to heat and moisture. In fact, its thermal resistance and insulation properties are even better than fiberglass.

A man on scaffolding installing polyurethane insulation in a wall of a house.
Plant-based polyurethane offers great insulation coupled with sustainability.

Another advantage of plant-based polyurethane is that its excellent at protecting against pests and mold.

27. Enviroboards

Fire-resistant Enviroboards are made up of sawdust, fiber cloth, and magnesium. They are usually used for roof lining, underlay systems, and wall lining. Eco-friendly fire board products are more robust than conventional boards. Plus, their water-resistant nature prevents them from warping over time.

A stack of white insulation Enviroboards with a black background.
Image courtesy of Enviroboards.

Because of its green manufacturing – natural dying and curing process, Enviroboards don’t release extra carbon emissions.

All in all, Enviroboards are a robust and versatile product suitable for several uses in refurbishment and construction projects.

28. Clay Brick

Clay brick is a natural material made using water and clay from the earth. It is eco-friendly, recyclable, and doesn’t release any harmful chemicals when in the landfill.

A pile of red and brown colored bricks.
Clay has a lot of thermal mass, which helps to even out temperatures over a short time period.

Moreover, clay brick is an energy-efficient and sustainable building material. During summer, it keeps your house cool, and during winters, it traps heat for a longer period.

29. Shipping Containers

Shipping containers are an excellent example of some truly top-quality waste in our society. There are hundreds and thousands of containers all over the globe, and they are generally only used for shipping purposes for about 15 to 20 years, after which they’re disposed of off even though they are still in excellent condition.

A lot of stacked old shipping containers sitting on the ground.
Surprisingly good as the basis for sustainable homes, shipping containers are becoming increasingly popular.

Such containers aren’t just spacious – they are incredibly durable, reasonably inexpensive, and environment-friendly (as they are reclaimed material). Thus, it doesn’t come as a surprise that these very durable containers are paving their way into the green construction scene.

Shipping containers have been used to build stores, houses, emergency shelters, artist studios, hotels, schools, apartment buildings, labs, and almost anything else you can think of.

Final Thoughts On Sustainable Building Materials

We are all aware of the impact our lifestyles are having on the planet, and most of us are doing our best to minimize our contribution to global warming and pollution of the environment.

The construction industry is one of the largest contributors to greenhouse gas emissions. According to Architecture2030, the built environment is responsible for just under 40% of global greenhouse gas emissions.

The production of building materials themselves is a significant contributor to emissions and a massive user of raw materials. Some estimates state that half of all raw materials used worldwide go into building products, and many cannot renew themselves.

Using more sustainable building materials and technologies can minimize the impact on our environment of constructing new buildings and renovating existing buildings.

If some of the materials mentioned in this article inspire you to build your next project more sustainably, please share them with us. We’d love to hear from you.

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