Corruption in the construction industry is not just a theft of tax revenue, it is a motivation for environmental crime: billions of tonnes of CO2 pumped into the atmosphere for projects which may have little social value and often pushed through despirte the opposition of affected local residents and with deep concerns among environmental licensing authorities.
Although the dangers are becoming clearer, this pattern continues to repeat itself. India and Indonesia are just entering their high-concrete phase of development. Over the next 40 years, the newly built floor area in the world is expected to double. Some of that will bring health benefits. The environmental scientist Vaclav Smil estimates the replacement of mud floors with concrete in the world’s poorest homes could cut parasitic diseases by nearly 80 per cent. But each wheelbarrow of concrete also tips the world closer to ecological collapse.
British thinktank Chatham House predicts urbanisation, population growth and economic development will push global cement production from 4 to 5bn tonnes a year. If developing countries expand their infrastructure to current average global levels, the construction sector will emit 470 gigatonnes of carbon dioxide by 2050, according to the Global Commission on the Economy and Climate.
Concrete 4: The dirtiest business
This violates the Paris agreement on climate change, under which every government in the world agreed that annual carbon emissions from the cement industry should fall by at least 16 per cent by 2030 if the world is to reach the target of staying within 1.5C to 2C of warming. It also puts a crushing weight on the ecosystems that are essential for human wellbeing.
The dangers are recognised. A report last year by Chatham House calls for a rethink in the way cement is produced. To reduce emissions, it urges greater use of renewables in production, improved energy efficiency, more substitutes for clinker (which is produced in heated ovens) and, most important, the widespread adoption of carbon capture and storage technology – though this is expensive and has not yet been set up in the industry on a commercial scale.
Architects believe the answer is to make buildings leaner and, when possible, to use other materials, such as cross-laminated timber. It is time to move out of the “concrete age” and stop thinking primarily about how a building looks, said Anthony Thistleton.
“Concrete is beautiful and versatile but, unfortunately, it ticks all the boxes in terms of environmental degradation,” he told the Architects Journal . “We have a responsibility to think about all the materials we are using and their wider impact.”
But many engineers argue that there is nothing nearly as good as concrete. Steel, asphalt and plasterboard take more energy to make than concrete. The world’s forests are already being depleted at an alarming rate even without a surge in extra demand for timber.
Phil Purnell, a professor of materials and structures at Leeds University, said the world was unlikely to reach a “peak concrete” moment.
“The raw materials are virtually limitless and it will be in demand for as long as we build roads, bridges and anything else that needs a foundation,” he said. “By almost any measure it’s the least energy-hungry of all materials.”
Instead, he calls for existing structures to be better maintained and conserved, and, when that is not possible, to enhance recycling. Currently most concrete goes to landfill sites or is crushed and reused as aggregate. This could be done more efficiently, Purnell said, if slabs were embedded with identification tags that would allow the material to be matched with demand. His colleagues at Leeds University are also exploring alternatives to Portland cement. Different mixes can reduce the carbon footprint of a binder by up to two-thirds, they say.
Arguably more important still is a change of mindset away from a developmental model that replaces living landscapes with built environments and nature-based cultures with data-driven economies. That requires tackling power structures that have been built on concrete, and recognising that fertility is a more reliable base for growth than solidity.