Materials
Concrete and Brick
In making materials selections, whether for a residential or a commercial project, the building materials utilised are ideally the most sustainable possible. In this article, we examine two common materials (concrete and brick) and how they perform as sustainable materials.
Concrete
While concrete has been a fundamental part of traditional and contemporary building techniques in architecture, there are many studies that highlight the negative impacts of cement-based material production within the construction industry.
For concrete (as well as stone and other ceramic materials) the biggest concern, in relation to sustainability, is the impact of the extraction of the raw materials. Extraction of the materials transforms the ground and thereby changing the surrounding landscapes and ecosystems. In addition, because of the heavy weight of the materials, transportation over long distances can also lead to high energy consumption.
However, there can be advantages to using concrete over other materials.
The strength and durability of concrete can ensure a long life for the material, often with very low maintenance requirements. Additionally, concrete is a material with good thermal mass performance; and used strategically can result in energy savings in terms of both air conditioning and heating.
Concrete also plays a role in resilient design decisions. As a material that does not burn, and one that retains its structural integrity in cases of flood, the use of concrete can lead to minimal wastage of materials in areas that are prone to fire or flood.
Concrete also performs well in comparison to other materials when looking at acoustic performance, durability, and robustness.
Recently, with the advent of new technologies, manufacturers have been using recycled concrete aggregates which helps to reduce landfill and carbon dioxide emissions. There have been some challenges with these sustainable alternatives in matching the strength and durability of traditional concrete but research continues to find solutions to these challenges.
Additionally, it is possible to recycle concrete at the end of a project life. Often the recycling process involves crushing the concrete into concrete rubble. Recycled concrete can be used in many ways including as gravel, paving materials and aggregates.
The case for using concrete as a building material when looking at sustainability is complex and often polarizing. In choosing concrete as a building material, it is imperative to consider the source of the concrete (local is best), the reason for using concrete (for example aiding in flood resilience) and whether using concrete can aid in minimising the use of other materials on the project.
Bricks
Like concrete, bricks are a fundamental material used in both traditional and contemporary buildings.
Made from organic minerals found in shale and clay, bricks are durable and generally require minimal maintenance across the building life span. Like any other building material, locally sourcing the bricks reduces the energy consumption. Choosing to use locally-sourced, recycled bricks makes the material choice better in terms of sustainability.
Bricks have a long life span but also are reusable. Where they are not being reused, bricks are recyclable thereby minimising end of building life environmental challenges.
Like concrete, brick does not burn making it a good choice for buildings in high fire-risk zones. Bricks do absorb water and cavity brick walls can potentially trap water and lead to subsequent mould problems. This is an important consideration when making materials choices in flood prone areas and it become very important that appropriate measures are taken to waterproof the bricks.
Blockwork
Blockwork (concrete blocks) are widely used in building projects.
Because of the cement in blockwork, it has a higher embodied energy than bricks. However, it is worth noting that because the concrete blockwork only needs to be cured in low temperature kilns unlike bricks.
Like bricks, blockwork is fire resistant making it a good choice for buildings in high fire risk zones. Like concrete itself, blockwork copes well in high moisture locations particularly where appropriate waterproofing measures are followed.
Unlike bricks, blockwork will typically be finished with a render or another applied finish for aesthetic reasons. The addition of the render or finish makes the materials choice less sustainable.
Conclusion
Choosing a building material is not always a simple choice. Factors such as design aesthetics, cost-effectiveness, longevity and environmental sustainability all form a part of the decision-making process. Understanding the purpose of the building material, the ease of building with the material and how the material performs as against the building life span become important factors in the material choice.