The surprising environmental impact of concrete

Concrete is one of the world’s oldest and most common construction materials mainly due to its low cost, flexibility, longevity and resilience to extreme climatic conditions, including hurricanes. It is a composite material of fine and coarse aggregate bonded with a fluid cement that cures and hardens over time. A favoured construction product for infrastructure projects worldwide, 30 billion tons of concrete is produced yearly for the construction of roads, railways, bridges, sewage systems, dams and buildings.

We know that the built environment contributes enormously to climate change; the production process for cement, a key component of concrete, accounts for an astonishing 8% of the world’s carbon footprint and buildings alone account for 40% of global greenhouse gas emissions. 2/3 of these emissions relate to the operational use of buildings, whilst 1/3 comes from construction. This includes all aspects of a building’s components, including the foundation, main structure, external fabric and interior fit-out.

In Bermuda, most construction projects utilise traditional building techniques and rely on imports of concrete’s bulk raw materials for new developments. The architecture practice, OBMI Bermuda is committed to reducing the island’s reliance on concrete and finding low carbon solutions through careful site analysis, working with the existing topography and collaborating with local structural engineers. As a practice, OBMI Bermuda is actively looking for alternative materials to specify it’s projects, such as recycled fill materials and aggregates; with crushed glass recently employed as an alternate fill material. Conscientious specification of materials and construction methods at the start of a project are some ways the construction sector can reduce its impact on the environment. OBMI Bermuda has used the geo-web retaining wall system to good effect on several projects around the island; reducing the amount of concrete compared to a traditional retaining wall system.

A growing number of developing technologies help reduce greenhouse gas emissions and the embodied and operational carbon footprint of buildings. Carbon capture technologies can be integrated into concrete production to reduce concrete’s carbon footprint and increase its strength. Even a slight improvement in the carbon footprint of concrete could see huge reductions in global greenhouse gas emissions. A focus has been on the research and development of improving the manufacturing process of cement which accounts for 95% of concrete’s manufacturing emissions.

Though Bermuda is presented with considerable geographic constraints, our architectural, engineering and construction organisations must work together with industry leaders and the government to seriously address the embodied and operational carbon of the buildings we are constructing. We must embrace emerging materials and technologies as viable alternative construction processes and evaluate the procurement of materials to reduce our island’s impact on the climate.