What does sustainable mean?

There is no universally agreed definition of sustainability. In fact, there are many different viewpoints on this concept and on how it can be achieved.

Etymologically, the word sustainability comes from sustainable + ity. And sustainable is, for instance, a composition of sustain + able. So if we start from the beginning, to <sustain> means “give support to”, “to hold up”, “to bear” or to “keep up”.

What is sustainability, then? Sustainable is an adjective for something that is able to be sustained, i.e, something that is “bearable” and “capable of being continued at a certain level”. In the end, sustainability can perhaps be seen as the process(es) by which something is kept at a certain level.

Nonetheless, nowadays, because of the environmental and social problems society is facing, sustainability is commonly used in a specific way.

Therefore, sustainability can be defined as the processes and actions through which humankind avoids the depletion of natural resources (which is influenced by the way societies are organised) to keep an ecological balance so that society’s quality of life doesn’t decrease.

In this way, we can say that resources exploitation, manufacturing operations, the direction of investments, technological developments, wealth distribution, institutional changes, among others, are being sustainable if they don’t hurt the ecosystem services and if they allow for society’s quality of life not to decrease.

How does it relate to building materials?

In building, environmentally-friendly materials (also known as green building materials) are those in which, for their production, placing and maintenance, actions of low environmental impact have been performed. ... These materials also have to be natural (soil, adobe, wood, cork, bamboo, straw, sawdust, etc.)

Nine sustainable building materials:

1. Green thermal insulation

2. Structural insulated panels

3. Recycled metal

4. Reclaimed wood

5. Engineered wood for cross-laminated timber buildings

6. Precast concrete slabs

7. Bamboo

8. Cork

9. Cement made out of recycled plastic

Current trends

Modular Construction Techniques to Eliminate Waste
Modular construction is a sustainable technique that builders are using to design structures faster, at a more competitive cost, and with maximum resource efficiency. Modular structures can be built within a controlled environment where wastage of resources is minimised and pollution is controlled.

Flexible Space Design to Improve Functionality
Flexible and dynamic construction is another sustainable design technique, which involves making a space functional for more than one purpose.
This dynamic design trend first started with reception areas being designed to also act as a lounge for both guests and employees. The technique is also expanding into hallways, classrooms, stairways and dining locations. Builders are trending towards designing offices to also become liveable apartments, hotels to become condos, and retail spaces to double up as community centres. 

Hidden and smart technology
As smart homes become even smarter and our lives centre more on technology, the seamless integration of sustainable and technological aides will become more prevalent.
Home automation is continuing to rapidly increase in popularity, with the smart home technology expected to have close to 42% household penetration by 2023. Not only does home automation make our lives easier, it makes it easier to further improve energy efficiency.
Roofing materials that act as solar panels, bench tops that charge your devices, new battery storage technology that reduces your need for always-on electricity will all help to reduce the energy consumption of your home. Coupled with advancements in automated systems that sync your environment to its optimum levels and maintain an equilibrium, these additions will become mainstream in 2020 and beyond.

Cost
Any definition of sustainability must necessarily take economics into account. Not just broader economic questions of productivity and economic growth, but the real-world cost of making and building things, and the cost of maintaining them throughout their useful lifespan. It also needs to be considered how long that lifespan is. A house made of wood may be relatively cheap to build, but ongoing costs such as painting must be factored in, and the total lifespan of wooden buildings is considerably less than brick or concrete constructions, though of course, the material itself is renewable within the lifespan of the building. The question of what is a more functional building is a further consideration, which relates to the final factor to consider.

Durability 
A key factor in designing sustainable spaces is specifying materials that last, add to the durability of the structure and minimise energy requirements of the project. To this end, weather barriers and a range of other protectants are an essential part of any sustainable building.

Top 3 sustainable building materials

1. Straw Bales

Cost: The cost of materials, including bales - these vary depending on where you are, but generally about $5-$7 per bale (delivered)

Straw bale building is a nod to the days when we built our homes from natural and locally-sourced materials. Instead of relying on technology and manufactured materials, we use what the earth provides. Straw bales are used to replace concrete, plaster, gypsum, and other building materials in walls. When sealed properly, they have a high insulating ability. As a renewable resource, straw is both sustainable and affordable.

2. Bamboo

Cost: Container-grown bamboo, on average, sells for $30 each, but can go up to $90 depending on the type.

The recent popularity of bamboo amenities such as furniture and utensils may make it seem trendy, but it has been used in construction for millennia. Its combination of light weight, tensile strength, and renewability make it an ideal replacement for expensive imported materials and an alternative to rebar and concrete construction, especially in areas with easy access to locally-sourced bamboo.

3. Recycled Plastic

Cost: $0.50 – 1.50 per kg for virgin PET, $0.20  - 0.30 per kg  for recycled PET, 0.06 – 0.08 per kg for mixed plastics.

Plastic is emerging as one of the more sustainable construction materials. Instead of sourcing, mining and milling new components, researchers are producing concrete made from ground-up trash and recycled plastics. This practice reduces greenhouse gas emissions and provides a positive new use for plastic waste that would otherwise be clogging landfills.

Where can you buy sustainable building materials?

Green Building Supply

1. ArchiBlox Designs World's First Prefabricated Carbon Positive House

Australian company ArchiBlox has released its design for the world’s first carbon positive prefabricated house. Representing a new movement in ArchiBlox houses, the carbon positive house provides the option for a more environmentally-conscious design, through both reducing embodied energy that accompanies new-home construction and maintaining positive-energy production. The groundbreaking product line began its first installation on February 8 at Melbourne’s City Square.

2. Colour House

3. S House

Vietnam's Vo Trong Nghia Architects has been tinkering away at the issue of providing practical, sustainable, and most importantly, cheap, homes. The result is the S House, a US$4,000 dwelling part-built using local, easily-obtained materials, including Palm leaf thatching and bamboo.

The interior of the S House is very basic and measures just 30 sq m (322 sq ft), with one large interior space. The building is prefabricated and can be disassembled into multiple small pieces for easy transport by local builders. Vo Trong Nghia Architects is still working on the design of the S House but the eventual plan is to mass market it.