How to Choose the Right Materials for your Eco-Friendly Building?
As the population increased, the resources started to decline. We are presently in the generation who are leading a very unsustainable lifestyle that depletes most of our natural resources. Rather than living with nature, we are living against nature.
When we are in the urge to protect the remaining environment ,we need to adopt more eco-friendly practices , change the pattern of production and consumption and conserving the resources for long term.
One can choose their own eco-friendly material according to certain criterias and the type of building to be built. A building can be eco-friendly, through its materials and construction techniques.
Criteria for choosing eco-friendly building Materials -
Climatic conditions and thermal comfort
Ease of Construction
Strength and durability
Local availability of material
Less embodied energy of the material
Rapidly renewable material
Material from recycled content
1.Climatic conditions and thermal comfort
The climatic conditions may severely impact the selection of building materials. It is important to know the conditions of a region along with the behavior of particular building material in that climate. For example, thick mud walls have high thermal mass (thermal mass- the ability of a material to absorb and store and release the heat energy) and reduce indoor temperature fluctuation. Hence, they are preferred in hot and dry regions where the diurnal fluctuation (variation between a high temperature and a low temperature that occurs during the same day) is high.
Passive cooling in this climate is usually more effective. We cannot blindly suggest materials based on the macroclimate, rather we should analyze other factors such as micro-climate, average temperature, annual rainfall, humidity levels, Fog, Mist, and much more. Thus, the climatic conditions may even greatly influence your decision in regard to the selection of building materials.
We can scientifically understand thermal comfort by comparing the specific heat values of different materials :
Specific Heat is the amount of heat per unit mass required to raise the temperature by 1degree celsius
Specific Heat of Concrete: 0.75 J/kgK
Specific Heat of Glass :0.84 J/kgK
Specific Heat of Steel: 0.49 J/kgK
Specific Heat of Brick: 1.05 J/kgK
Specific Heat of Clay :1.26 J/kgK
2.Ease of Construction
According to each site's material availability, climate, Contours, Labour availability one can choose their desire method of Construction.
In places where there is a lack of skilled labour, Earthbag Construction is a go-to method. In a site of abundant mud availability, mud walls is a good option. According to the availability of water and skilled labourers, one can choose Wet Mud Methods like Cob, Adobe or Dry Mud Methods like Rammed Earth, Earthbag, Compressed Mud Blocks.
Simpler methods can be chosen like Interlock brickwork or exposed Brickworks.
Availability of Stones in the vicinity will be a great virtue to use for foundations. Sometimes, skilled works like Madras Terrace Roof or Chettinad Plasters will require highly skilled labourers, who availability and costs are to be checked.
3.Strength and durability
The strength of a material is its ability to withstand load without any deformation. Every eco-friendly material needs to be stabilized in order to increase its compressive and tensile strength. Especially when we are building load-bearing structures we need to analyse the compressive strength of the materials. Again the strength also depends on how effective it responds to climate, the type of load that is to be experienced on the building, quality of the raw materials and the construction technique.
Durability of a building material is the capacity of a material to be functional without excessive maintenance and to perform well over its design lifespan. Their eco-friendly nature, doesn’t mean to compromise on its durability. It must last longer for the best energy conservation, waste removal and also for reducing the cost of rework and repair. A durable product will have lesser chances of getting spoilt which will improve your profit margin by preventing constant fixtures and replacements. For example, bamboo is one of the popular eco-friendly materials which is known for its light-weight and strength. Contradicting to this, untreated bamboo can last 2-6 years internally, and less than a year if exposed to rainfall. So, to increase the durability it needs to be treated to resist insect attacks and internal decaying.
4.Local availability of material
The products used must be locally produced as this will help in reducing the cost of transportation energy as well. Transporting goods from other areas will waste natural resources like petrol and diesel. It will also boost the economy of the local government as the goods are locally produced.
5.Less embodied energy of material
Embodied energy is an assessment of the energy required to manufacture any building material. This includes energy required to extract raw materials from nature, energy used to transport raw materials to manufacturing units and the energy used in manufacturing activities to provide a finished product.
The embodied energy can be reduced by 30% when local materials are used.
The embodied energy of Concrete Masonry - 508GJoules
The embodied energy of Mud Brick - 370GJoules
Always choosing locally produced materials will lead to choosing less embodied energy.
6.Rapidly renewable material
The earth’s resources are getting reduced at a disturbing rate and hence the need to use renewable resources. When we use the resources from the earth, the ecosystem is disturbed and many animal and plant species become extinct. We can use material that are rapidly renewable or reused and hence we can reduce the usage of non-renewable resources associated with building construction .
7.Materials from recycled content
We need to check the recyclability of the product that is used for the building. This would include assessing the material as to whether it can be reused for any other purpose. If the material cannot be reused and will go as a waste afterward cannot be considered eco-friendly. You must also check whether the material used is made in combination with recycled material or is an entirely recycled material to fit into the recycled category. For example Fly ash bricks, bamboo.
Cost is completely a personal choice. One can choose their eco-friendly material according to their needs and affordability.
No matter what the core material is, it makes the most difference on what plaster is being applied on the outside and inside. The reflectivity, absorptivity, emissivity, colour of the plaster can decide the heat transfer and humidity control . Surface treatment and the selection of surface material can help in reducing the heat load . For example, for hot dry climate light, colored or shiny surfaces is used to reflect a large part of incident solar radiation , thus much less heat will actually enter the building. Go for eco-friendly finishes like mineral colors, mud and lime-based finishes instead chemical paints and sleek finishes respectively.
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