Green architecture is the raging trend of the hour. This field of design uses natural or recycled materials to create more environmentally conscious and efficient homes, which are not only easier on the pocket. Designer need to make good eco-friendly decisions in their choice of materials. Discover below 10 alternative green building materials for your next project.
Straw has been used for construction since the Palaeolithic era. “Cozy” is how most straw bale constructions can be defined. Straw bales have 3 times the R-Value of conventional home insulation, which gives them excellent fireproofing and sound-proofing qualities.
Straw bale is cheap, the tight packing makes it have 3 times greater fire resistance than traditional walls, is soundproof, non-toxic, resistant to collapse during earthquakes and easy to access and assemble.
However, one major disadvantage of straw bales is that they cannot get wet, which makes them unviable in humid areas. The bales can also attract insects and rodents, and due to the novelty of the material, it can be difficult to get insurance for straw bale constructions.
Invented by accident in the early 2000s, Ferrock shares a lot of building characteristics of concrete and can be used as a replacement. It is made using steel dust that is often a waste product, and silica. When this combination is reacted with carbon dioxide it creates iron carbonate which binds the carbon dioxide present in the atmosphere into the Ferrock.
Ferrock is 5 times stronger than concrete, has higher compression durability, as well as more flexibility which makes it a more stable construction material than concrete. Ferrock is also CO2 negative which means unlike most building materials, it absorbs carbon dioxide instead of emitting it. Ferrock can also survive saltwater without erosion, even becoming stronger due to the presence of chlorides in the water. Lastly, due to its composition from recycled and waste-product materials, it is much more sustainable than concrete.
The constraints of using Ferrock as a mainstream construction material are the high costs in large-scale constructions such as roads, the limited supply of silica and steel dust for scalable production, and a lack of long-term testing of the durability, lifecycle, and resistance in unknown or unfamiliar circumstances or pressure.
Mycelium is a network of fungal threads or hyphae that grow underground but can also grow in the roots of rotting tree trunks. The fibres grow, strengthen and elongate, eventually weaving into each other to form bonds that create a surface. By building stacked layers, mycelium can form dense coatings. Different densities of Mycelium can be grown together, which makes it a fire-resistant material to replace plastics, concrete, and wood. Mycelium can be used in moulded form for facades, furniture, interior pieces, etc.
Mycelium is a highly sustainable material due to its natural growth, waterproofing capabilities, high-temperature resistance and high structural integrity at the appropriate proportions. Dry, Mycelium is lighter but stronger than concrete per unit weight. The intertwined growth abilities eliminate the need for any bonding material. Further, if kept in favourable and stable conditions, bricks made of Mycelium can last for 20 years. Mycelium bricks are prone to environment-based changes such as contraction and expansion if they come in contact with the moisture-laden ground, thus reducing their efficiency as a building material.
Grasscreate or “grass concrete” are concrete systems that are cast on-site and reinforced with videos created by styrene void formers, which are essentially concrete blocks with gaps that are filled with grass.
Grasscrete offers significant structural advantages like high load-bearing, differential settlement resistance, great drainage capacity, and elimination of kerb edges. The relatively lighter weight of Grasscrete also makes it economical to ship globally.
As Grasscrete is grass-based, it comes with disadvantages like the need to be watered, mowed, and fertilized. It is also twice as expensive as asphalt and has shorted lifespan than concrete and asphalt-based blocks.
Hempcrete is a natural building block that is made by mixing the inner woody core of the hemp plant with a lime-based binder. Hempcrete has a high silica content which allows it to bind with lime, making it unique amongst all-natural fibres. It makes an excellent cement-like insulating material with a fraction of the weight of concrete of the same volume. Hempcrete is not a structural element, but an insulting infill which also helps to reduce racking to some extent.
There are many benefits to using Hempcrete, primarily that is an affordable insulation material, it has exceptional moisture handling and resistance, and it can be made from an agricultural byproduct which makes it sustainable and non-toxic. Hempcrete also fits in well with conventional framing techniques.
Some cons of using hempcrete are that as it occupies more space, walls need to often be thicker which reduces carpet area, it has low compressive strength so cannot be stacked densely, it cannot bear direct loads due to low elasticity and therefore, cannot be used for heavy loads without a support frame.
It is one of the oldest construction methods which involves building floors, foundations and walls using compacted natural materials like earth, chalk, and lime. Rammed earth can easily be produced from suitable local soil. Rammed earth has a high thermal mass, which allows it to regulate temperate by absorbing heat in the morning and releasing it at night. The colours of rammed earth are natural, textured and varied. Rammed earth blocks are also easily repaired by using the same soil mixture to fill in blemishes and cracks.
Using rammed earth requires extensive knowledge of local soil characteristics, and the design considerations and requirements. Rammed earth blocks are not great insulators and require additional insulating material. In areas of high rainfall, rammed earth walls may be prone to erosions. Creating rammed earth structures is labour intensive and does not have scope for correction once built.
Timbercrete is made using sawdust and wood chips which are a by-product of the timber industry. It works as a lightweight insulating concrete material and closely resembles traditional concrete in look, feel and sound absorption capability.
Timbercrete is mouldable and has a low environmental impact as it can be produced from local waste-wood materials. Timbercrete does not have a well-defined process for mixing, which means there are no regulations or quality control enforcements possible. Further, Timbercrete is not yet tested for long-term stress and load-bearing.
Bamboos are the fastest-growing plants in the world, almost 3 times faster than other plants. It has been conventionally used in Southeast Asia and South America where it is most easily grown. Some regions also use bamboo to hold up suspension bridges or places of dwelling. Bamboos are also easy to split, can be shaped into a square shape, and can be bent and cooled to retain desired shapes. A Structural Frame Technique is used for bamboo-based construction where the roof, walls and floor are interconnected for improving stability.
Bamboo has high tensile strength due to axially positioned fibres, is fire resistant up to 4000 Celsius, and is earthquake-proof due to its high elasticity and flexibility. Bamboo can also be easily transported due to its lightweight, which makes it cost-effective.
Some drawbacks of using bamboo are that it required preservation once harvested, it loses much more water and shrinks significantly as compared to other timbers and needs to be well treated against fungus and insects to enhance durability and structural integrity.
Cob is a building material made of subsoil, water and fibrous organic materials like straw or lime. Sometimes cob is also modified with sand or clay to varying its properties based on the construction requirements. Cob is also known by other names like adobe, lump clay, chalk mud and swish. Cob has been used for centuries for creating structures but has recently seen a revival as a building material with sustainability movements.
Cob is extremely inexpensive, provides creative flexibility due to easy moldability and colouring possibilities, and is brilliantly resistant to earthquakes while having high thermal resistance and soundproofing.
It is labour intensive to produce cob, and it is not ideal for wet or humid regions due to being made from mud. Knowledge of cob and its features, as well as expert design skills, are required to use cob effectively. It is often difficult to get permits or insurance for modern buildings made of cob, due to their non-conventional and usually “poor-people” perception. Lastly, cob walls are prone to shrinking after drying, which leads to longer timelines for completion.
Cork is used as a flooring material that uses sheets of ground-up and compressed cork bonded with resins. The bark of the cork oak tree is harvested from the commercial oak tree. Cork flooring can be modified to resemble other materials for floor construction such as marble, concrete and even hardwood.
It is a hypoallergenic and antimicrobial material which makes it great for floors. Cork can also repel dust mites and dirt, improving interior air quality and resisting mildew and moulds. Cork is extremely affordable depending on the finish and quality. It is also an excellent insulator, as the small air-filled chambers in the cork’s cellular structure trap heat and disperse it evenly. Cork flooring can also be refinished to change its look and texture while being eco-friendly and easy to install and maintain.
The problem with cork is that it needs water sealing to avoid water absorption, is easy to damage due to the softness of the material, and is also temperature sensitive, liking expanding and curling up in high humidity. Finally, cork also fades with time with exposure to direct sunlight, thereby being suitable for flooring in areas without large windows or open areas.
Check out some more alternative materials for sustainble construction on the Infurnia Blog.