Make sourcing local materials a building priority

In the midst of the pandemic, a report by the think tank Circular Economy (The Circularity Gap Report 2020) that humanity was quietly devouring the earth went unnoticed. While the amount of material consumed by humanity had passed 100 billion tonnes since 2017, the proportion being recycled was falling.

This meant that virgin materials were being used up while building waste was growing. Half of this 100 billion tonnes was sand, clay, gravel and cement – all used for building.

Coal, oil and gas made up another 15% and metal ores 10%. The final quarter comprised the plants and trees used for food and fuel. This means that over 60% of minerals extracted were used for building-related activities.

A third of this was wasted, mostly to landfill and mining spoil heaps. From the third of materials still in use after a year, such as buildings and vehicles, 15% was emitted into the atmosphere as greenhouse gases. Nearly a quarter, including plastic, found its way into oceans.

Of the 100 billion tonnes, 40 billion was used for housing while 31 billion tonnes of waste was generated from building and infrastructure. The ONS estimates that the UK’s total household spending on home repairs, maintenance and improvements is around £40bn annually, so much waste can be designed out by British architects.

Non-renewable building materials such as sand are needed for large projects. Sand and clay have become the world’s most trafficked minerals, often by criminal gangs. Extractions put the local ecology and people in danger.

In poor countries, brick production results in over-extraction of clay from agricultural land and pollution. At present, the UK imports granite from India and China, resulting in high embodied energy for the stone. Poor countries and people are the victims, driven by demand from rich nations. Extraction and mining also use illegal labour.

Treating the world’s resources as limitless and believing in a linear economy is driving the planet to disaster. Sourcing local materials should be a priority for all architects, followed by the reduction of material needs.

As many materials cannot be usefully recycled or reused, particularly plastics, stone and concrete, reuse – and particularly recycling – cannot be the preferred solution. Even most bricks can only be downcycled due to the use of cement mortar. 

So when choosing materials, think about embodied carbon, reuse and recyclability, transportation, ethical extractions, supply chains and buildability.

Sumita Singha is a director at Ecologic Architects