The construction industry consumes 36% of the world’s energy, and uses non-renewable materials that create pollution. Many of the natural materials used in building construction can be sourced on-site, saving on transport costs.
Sheep’s wool, for instance, is a great insulator that can be regrown quickly. Cork is also a hard-wearing material that comes from a renewable source and absorbs carbon dioxide while it grows.
Cob
Cob is an ancient building material which uses a mixture of clay soil, sand and straw in different proportions to form a rock hard, finished structure. It can be used to build anything from cottages and benches, to ovens and houses. It is a versatile material which can be sculpted into unique and beautiful buildings. Cob buildings are extremely durable and if correctly built and maintained will last for generations. Cob buildings need large overhangs and stone or block plinths to minimise the amount of rain that reaches the walls, but when they are properly designed and insulated this is not a problem.
Using natural materials can also be much more environmentally friendly than using industrialised building products. The raw materials can be sourced close to the building site and do not require transportation costs. The material does not need to be heated or treated in factories so fewer carbon emissions are produced. This is especially important if the building is going to be used as a living space.
Cob is a great material for sustainable building because it does not release any toxic chemicals. It is non-toxic and if it is no longer used it will naturally disintegrate back into the earth, leaving no trace of its existence. When it comes to sustainability, few materials can compete with cob.
Clay
Throughout the world clay has been used as one of the most important building materials. It can be found in ceramic works, as well as in traditional and modern construction. It has an ability to solidify under certain conditions, which makes it a durable material for buildings. Many artists of the past and present use it to create their masterpieces. It is also an ideal material for inclusion in a sustainable home or building project.
Clay is a fine-grained natural soil material composed of kaolinite and other clay minerals (hydrous aluminium silicates) and typically with small amounts of quartz, feldspar and organic matter. It has been used as a building material for millennia, especially baked into bricks. It has the advantage of being a readily available, local and renewable resource. It is very adaptable and can be mixed with other natural materials like straw, sand and cement to make combi-materials.
In addition, clay is a relatively cheap material to work with and can be processed in numerous ways. It can be mixed by hand, with a mixer or even stamped by water buffaloes, which is an excellent example of a sustainable, affordable and inclusive building technique. Using clay as a binding agent in the construction of earthbags, cob or rammed earth can help reduce dependence on expensive and heavy concrete or cements.
Cork
Cork is not only an eco-friendly material that has made its way back into the spotlight thanks to manufacturing advancements and increased sustainability awareness, it’s also a highly durable and visually appealing construction material. Whether used for flooring, insulation, walls or structures, cork provides a wide range of energy-efficient functions including thermal and acoustic insulation as well as a natural sound dampener.
The use of cork in building construction has been around for thousands of years. The ancient Egyptians used it for beehives, women’s shoes and even ship hulls, while Romans used it in their houses to keep them warm in winter and cool in summer. It is produced from the bark of the cork oak tree and combines a number of unique properties that make it an excellent alternative to traditional materials.
A green buoyant material, cork is extremely light yet also very strong and flexible. Harvesting the bark does not harm the tree, allowing it to continue to grow while still producing cork. The material is made from a renewable resource, with all parts of the tree being utilised during production.
A recent project by Matthew Barnett Howland showcases a house with a cork facade. The use of cork in this home was intended to promote a connection with nature, which is an essential element of biophilic design and linked to improved wellbeing.
Straw Bale
Straw bales can be a great option for those who want to build a home in a more sustainable manner. The use of straw as a building material can result in significant reductions in wood and concrete use (which can contain harmful chemicals). Additionally, using straw for insulation purposes eliminates the need to install unhealthy materials such as fiberglass which contains formaldehyde or plywood which is often glued with chemically produced products.
The key to a successful straw bale construction project lies in the proper preparation of the bales. First and foremost, the bales must be dry upon purchase. If the straw has any moisture at all it will compress over time when placed under structural loads from floors and roofs. To prevent this, the bales must be precompressed by placing them in a frame that will withstand compression loads such as a conventional ‘buck’.
Another important consideration is the location of the straw. It must be available locally so that it does not require excessive transportation which can also have an adverse environmental impact. Additionally, straw requires a lot of processing so that it can be used as a building material. This is a process that takes up to a month and involves wining, shaping and firing.
The most commonly used straw for building is rice, wheat, barley rye or oat straw which is harvested and baled with a combine harvester. It is best if the straw is from the same area as the construction site as the bales will need to be monitored on a daily basis for moisture. In addition to checking for moisture, it is a good idea to water the bales on a regular basis. However, it is important to note that the amount of water that can be applied to a straw bale should not exceed one gallon per day because excess water could wash away nutrients.