The Carbon Cost of Concrete

The Carbon Cost of Concrete

World’s most used building material produces bigtime CO2 emissions

Sustainable construction is no longer a ‘nice-to-have.’ With global temperatures rising and urgent warnings to cut emissions from the IPCC, the construction industry must take action to reduce its hefty contribution to greenhouse gas production and increase sustainability. 

Are there ways to improve sustainability in construction? Options range from creating more energy-efficient buildings to responsibly sourcing materials and choosing more carbon-friendly materials, like low carbon concrete. Cement, the main ingredient in concrete mix, is a particularly offensive player when it comes to sustainability.

Did you know the impact of carbon concrete?

If the cement industry were a country, it would be the third-largest carbon dioxide emitter in the world, behind only the US and China.

Choosing low carbon concrete is an opportunity to massively decrease the cement industry’s carbon footprint. At scale, sustainable concrete has the potential to reduce over 70% of the cement industry’s greenhouse gas emissions by 2050, the equivalent of 4% of world-wide all GHG emissions. That’s major impact!

Why do we need low carbon concrete?

Simply put, because concrete production makes a lot of CO2, and we make a lot of concrete.

Concrete is the most widely used construction material in the world. It is the second most used material in the world after water. The global population continues to grow. To meet these demands for housing, sanitation, business and commerce needs, big construction projects which rely heavily on concrete as the main building material are underway on nearly every continent. 

As a result, the concrete industry is growing steadily—at an annual rate of 8%—at a time where there’s a pressing need to cut global emissions, and quickly. Emerging markets like India and Brazil are urbanizing and expected to further drive the demands for concrete, yet the industry is facing societal, financial, and increasingly, regulatory pressure to decrease emissions rapidly.

Why does cement production emit so much CO2?

It’s the sheer scale of the manufacturer and use of concrete that makes it a top contributor to global greenhouse gas emissions—the industry is responsible for 7% of worldwide CO2 emissions. 

The majority of concrete’s carbon footprint comes from the production of clinker, a main component of cement. Producing clinker results in chemical and thermal combustion processes called calcination creates 50% of the processes’ GHG emissions. Because this CO2 comes from a chemical reaction, it can’t be eliminated by switching to more energy-efficient fuels. Today there are a few options for low carbon cement mixes that either eliminate or decrease the amount of clinker in cement mixes. Substitutes such as fly ash and blast-furnace slag are used instead. 

High fuel requirements are another big contributor to cement production’s big carbon footprint. Heating the kilns to high temps required to make cement is responsible for another 40% of emissions created.

Low carbon cement mixes options

  • Use "cleaner" ingredients than ordinary concrete—ingredients that reduce the number of GHGs emitted during production
  • Are produced in plants powered by clean energy
  • Are available at competitive prices
  • Outperform ordinary concrete in terms of material strength

Challenges low carbon concrete faces

Cement, invented by Joseph Aspdin in 1840, has remained essentially unchanged since then. Architects, engineers, contractors, and project managers have historically been hesitant about new building materials for obvious reasons, and innovation has long taken a back seat in the cement industry. 

Additionally, the big players in the concrete industry are wary of new products that challenge existing business models.

Recommendations for sustainability in the construction industry

Work with contractors, architects, and project managers who focus on sustainability and have the expertise and experience to design and manage green construction projects. Our team at The Bridge Group has a dedicated Sustainability Manager poised to assist on your project. 

A confidential technology company of ours recently expanded its headquarters with a focus on productivity, collaboration, and sustainability. It includes open spaces to foster collaboration as well as quiet, focused workspaces and a rooftop garden with walking paths. The highly sustainable campus was designed to reduce environmental impact from every angle, including building materials like low carbon concrete. 

If you’re in the Bay Area and seeking a low carbon concrete option, we highly recommend Central Concrete. Central Concrete is an industry leader in sustainable concrete solutions, providing various EPD mixes designed for performance beyond strength.

In order to reduce the carbon footprint of concrete, Central Concrete uses cement ingredient replacements, recycled fresh concrete, and recycled concrete aggregate. They also use CarbonCure technology, an innovative mix that contains captured recycled waste CO2. 

In order to reduce the environmental impact of the concrete used in projects, design standards should be updated to support the use of Type III EPD certified cast-in-place concrete. A final word to Project Managers and Architects- be certain to ask your concrete provider whether they provide a low carbon concrete mix! 

What’s your experience using a low carbon concrete mix for a project, if any? Share in the comments below.