Exploring the Use of Organic Materials in Building: Beyond Hobbit Homes and Basic Mud Structures
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In the pursuit of a greener future, the construction industry is increasingly turning to natural materials for building projects. This article explores some of the most sustainable options and key factors to consider when choosing these materials.
Natural materials such as bamboo, rammed earth, hempcrete, reclaimed wood, recycled steel, and cork are gaining popularity due to their renewable nature, low embodied energy, and environmental benefits.
Bamboo, for instance, grows extremely quickly (3–5 years) and regenerates naturally without replanting, making it highly renewable. Rammed earth, especially when unstabilized and locally sourced, has low embodied energy compared to conventional materials.
Materials like rammed earth offer excellent thermal mass, regulating indoor temperature and lowering heating/cooling needs. Hempcrete is resistant to pests and mold, and rammed earth is fireproof and durable against loads.
Recycled steel reduces demand for new raw materials and saves energy compared to virgin steel. Bamboo also acts as a carbon sink by absorbing CO₂ rapidly. Natural and non-toxic materials like rammed earth avoid harmful off-gassing and can regulate indoor humidity, promoting healthier indoor environments.
Some materials, such as rammed earth and reclaimed wood, add a natural, rustic charm and connect buildings to their local context. Using local materials reduces transportation emissions and supports sustainable supply chains.
Straw bale construction, which dates back 400 years in Germany, is another sustainable option. When protected from the elements correctly, straw bale insulation can easily last for decades. Straw homes have been built since the Stone Age, roughly 2.5 to 2 million years ago.
In Nebraska, straw bale homes really took off due to the scarcity of trees and abundance of wheat. In Europe, estimates suggest that the top 7 European countries constructing wooden houses are currently Germany, UK, Sweden, Finland, Austria, Italy, and Estonia.
When it comes to CO₂ storage, the use of engineered wood products in the European building sector could have the potential to store roughly 46 million tonnes of CO-eqv. per year in 2030.
It's important to note that every location in the world is slightly different in terms of temperature, humidity, air quality, wind strength, rainfall, etc. Therefore, it's crucial to consider climate suitability when choosing materials.
Cork represents 1% of Portugal's GDP with annual exports totalling over €1,346 million. Europe produces 144 million tonnes of straw as a waste product from wheat every year.
Architects, planners, designers, local authorities, and individuals can make a real difference with the materials they choose. A life cycle analysis is a leading tool for the assessment of impact that products and services have on the environment.
In summary, the choice depends on balancing environmental impact, climate suitability, structural needs, and desired aesthetics to achieve genuinely sustainable construction outcomes.
Interestingly, most cob (mud) homes found in the UK are between 200 and 400 years old. Around half of the world's population still live in homes made of earth. Mud has been the world's primary building material for 10 millennia and is still used by 1/3 of the world's population for housing.
The first mud-based mix used for construction (cob) can be traced back to the 11th century in northern Africa. Hemp-based structures date back to Roman times. Hemp currently makes up less than 0.5% of the 3.3 million tonnes of insulation materials used annually (2020).
Savings of up to 75% can be made in energy and fuel costs compared to a conventional house when using straw. Raw earth has 1/40 the carbon footprint of concrete. In 2002, 1 in 6 homes built in the UK were constructed using timber frame methods. By 2014, 1 in every 3 detached homes were built with a timber frame.
Bamboo can sequester 6-13 Mg (metric ton) per ha per year, or up to 600 tonnes per hectare over a 30-year period. Outside of Europe, the USA, Canada, Japan, Australia, and parts of East-Asia are among the top builders of wood houses.
In 2015, the European wooden house industry was worth €7.74 billion. The cost of a small house with two rooms made of straw bales may cost around £10,000 to build, and a large 3 bedroomed house up to £40,000.
In conclusion, the guide presented here is based on the ACAN online seminar on natural materials from July 2021. By considering factors such as renewability, embodied energy, thermal performance, durability, carbon footprint, health and indoor air quality, aesthetic and cultural compatibility, local availability, and sourcing, we can move towards more sustainable construction practices.
Science plays a crucial role in the development of environmental-science strategies to mitigate climate-change effects. For instance, technological advancements in engineered wood products could potentially store 46 million tonnes of CO-eqv. per year in the European building sector by 2030, contributing to the reduction of carbon emissions. Additionally, understanding the thermal performance, durability, and carbon footprint of natural materials like bamboo, rammed earth, and straw bale is essential in the pursuit of sustainable technology for environmental-science applications in the construction industry.
