It is well understood there are two types of carbon emission throughout the life cycle of a building - Operational and Embodied Carbon. The former refers to the carbon dioxide emitted from a building's energy consumption (such as heating, lighting, etc.), essentially when it is in "operation". Embodied Carbon, however, is associated with those emissions from construction activities and use of building materials throughout their lives - from manufacturing, transportation, installation, maintenance and disposal. Another important distinction about Embodied carbon emission is that it cannot be reduced once the building is built! Currently, it makes up 11% of global GHG emissions every year and is expected to become a more significant contributor to global warming!
Between now and 2060, it is estimated that the world's population will be doubling the amount of building floor-space.* With the new energy codes and other legislations demanding higher energy performance from and electrification of new construction, as well as the increasing use of renewable energy, much of the carbon footprint of these buildings will shift to the embodied carbon associated with building materials. The projected amount of embodied and operational carbon emission from global new construction will almost match up in 2050.* Tackling the source and impact of embodied carbon has therefore become a key focus of the building industry and A+E community's collaborative efforts to get to carbon neutrality!
* Architecture 2030 and Carbon Leadership Forum
If concrete were a country, it would be the third largest emitter of greenhouse gases on Earth, behind only China and the United States. Its key ingredient - Cement - contributes to 7% of the world's total CO2 emission. Emission from cement production is also one of the most difficult emissions to eliminate due to existing policies and infrastructure.
There are many ways that architects can look at to make significant impacts through our design and construction process. One way would be reusing existing buildings instead of constructing new ones. The more we reuse the existing buildings, the less of an impact it has on the environment because we use less virgin materials thus avoiding the release of carbon into the environment through their lifecycle (extraction, processing, manufacturing, and transport). Also this would help in decreasing the amount of waste associated with the demolition of existing buildings. Renovation and reuse projects typically save between 50 and 70 percent of the embodied carbon compared to constructing a new building from scratch.
Here are a few technologies, innovations and practices that can help to reduce or “neutralize” the carbon impact of concrete:
Supplementary cementing materials (SCMs) are commonly used alternates to cement that not only reduce the carbon emission of concrete but also contribute to the properties of hardened concrete through hydraulic or pozzolanic activity. Typical SCMs are fly ashes, slag cement (ground, granulated blast-furnace slag), and silica fume. These cement alternatives can be used individually with portland or blended cement or in different combinations. They are often added to concrete to make concrete mixtures more economical, reduce permeability, increase strength, or influence other concrete properties.
For the Moffett MT2 Building 6 project, DES’ worked with their construction partners to target 50% cement replacement in concrete (both office building and parking garage except for the post tensioned slab which remains at 30% recycled content):
PLC, also known as Type 1L cement, is a type of blended cement that contains between 5 and 15% limestone. It replaces some of the clinker in the cement, which is the main energy-intensive ingredient, with limestone, and can result in 10% reduction of carbon emissions from conventional cement's production. Concrete mixes designed with PLCs are compatible with all supplementary cementing materials.
LC3 is a new type of cement that is jointly developed by the École Polytechnique Fédérale de Lausanne (EPFL), Indian Institute of Technology (IIT) Delhi, and a few other research institutions. It is based on a blend of limestone and calcined clay. LC3 can reduce CO2 emissions by up to 40%, and is made using limestone and low-grade clays which are available in abundant quantities. Apparently, the manufacturing process does not require capital intensive modifications to existing cement plants. About 40 cement companies in 25 countries are already interested in producing LC3 as a low-carbon cement alternative.
Carbon sequestration converts CO2 into a mineral which is then trapped onto the concrete.
CarbonCure is an emerging carbon sequestration technology that is capable of performing just as effectively as fly ash when it comes to concrete strength. It traps the CO2 from the cement manufacturing process, converts them into carbonates and injects them into concrete mixes. Once injected into the wet concrete mix, the CO2 reacts with calcium ions from cement to form a nano-sized calcium carbonate mineral that becomes permanently embedded in the concrete. CO2 mineralization improves concrete’s compressive strength, enabling better concrete, while reducing the concrete’s carbon footprint.
If you are interested in finding out more about low or neutral carbon concrete innovation and best practices, check out these links below:
https://www.neuconcrete.org/resources
https://www.shapedbyconcrete.com/#roadmap-to-carbon-neutrality
https://materialspalette.org/concrete/
DES does not endorse these products and technologies.
This blog post originates from a low-carbon design presentation by the DES sustainability team. Special thanks to Jyothsna Giridhar and Waibun Lee for some of the content materials and low-carbon concrete research.
It is well understood there are two types of carbon emission throughout the life cycle of a building - Operational and Embodied Carbon. The former refers to the carbon dioxide emitted from a building's energy consumption (such as heating, lighting, etc.), essentially when it is in "operation". Embodied Carbon, however, is associated with those emissions from construction activities and use of building materials throughout their lives - from manufacturing, transportation, installation, maintenance and disposal. Another important distinction about Embodied carbon emission is that it cannot be reduced once the building is built! Currently, it makes up 11% of global GHG emissions every year and is expected to become a more significant contributor to global warming!
Between now and 2060, it is estimated that the world's population will be doubling the amount of building floor-space.* With the new energy codes and other legislations demanding higher energy performance from and electrification of new construction, as well as the increasing use of renewable energy, much of the carbon footprint of these buildings will shift to the embodied carbon associated with building materials. The projected amount of embodied and operational carbon emission from global new construction will almost match up in 2050.* Tackling the source and impact of embodied carbon has therefore become a key focus of the building industry and A+E community's collaborative efforts to get to carbon neutrality!
* Architecture 2030 and Carbon Leadership Forum
If concrete were a country, it would be the third largest emitter of greenhouse gases on Earth, behind only China and the United States. Its key ingredient - Cement - contributes to 7% of the world's total CO2 emission. Emission from cement production is also one of the most difficult emissions to eliminate due to existing policies and infrastructure.
There are many ways that architects can look at to make significant impacts through our design and construction process. One way would be reusing existing buildings instead of constructing new ones. The more we reuse the existing buildings, the less of an impact it has on the environment because we use less virgin materials thus avoiding the release of carbon into the environment through their lifecycle (extraction, processing, manufacturing, and transport). Also this would help in decreasing the amount of waste associated with the demolition of existing buildings. Renovation and reuse projects typically save between 50 and 70 percent of the embodied carbon compared to constructing a new building from scratch.
Here are a few technologies, innovations and practices that can help to reduce or “neutralize” the carbon impact of concrete:
Supplementary cementing materials (SCMs) are commonly used alternates to cement that not only reduce the carbon emission of concrete but also contribute to the properties of hardened concrete through hydraulic or pozzolanic activity. Typical SCMs are fly ashes, slag cement (ground, granulated blast-furnace slag), and silica fume. These cement alternatives can be used individually with portland or blended cement or in different combinations. They are often added to concrete to make concrete mixtures more economical, reduce permeability, increase strength, or influence other concrete properties.
For the Moffett MT2 Building 6 project, DES’ worked with their construction partners to target 50% cement replacement in concrete (both office building and parking garage except for the post tensioned slab which remains at 30% recycled content):
PLC, also known as Type 1L cement, is a type of blended cement that contains between 5 and 15% limestone. It replaces some of the clinker in the cement, which is the main energy-intensive ingredient, with limestone, and can result in 10% reduction of carbon emissions from conventional cement's production. Concrete mixes designed with PLCs are compatible with all supplementary cementing materials.
LC3 is a new type of cement that is jointly developed by the École Polytechnique Fédérale de Lausanne (EPFL), Indian Institute of Technology (IIT) Delhi, and a few other research institutions. It is based on a blend of limestone and calcined clay. LC3 can reduce CO2 emissions by up to 40%, and is made using limestone and low-grade clays which are available in abundant quantities. Apparently, the manufacturing process does not require capital intensive modifications to existing cement plants. About 40 cement companies in 25 countries are already interested in producing LC3 as a low-carbon cement alternative.
Carbon sequestration converts CO2 into a mineral which is then trapped onto the concrete.
CarbonCure is an emerging carbon sequestration technology that is capable of performing just as effectively as fly ash when it comes to concrete strength. It traps the CO2 from the cement manufacturing process, converts them into carbonates and injects them into concrete mixes. Once injected into the wet concrete mix, the CO2 reacts with calcium ions from cement to form a nano-sized calcium carbonate mineral that becomes permanently embedded in the concrete. CO2 mineralization improves concrete’s compressive strength, enabling better concrete, while reducing the concrete’s carbon footprint.
If you are interested in finding out more about low or neutral carbon concrete innovation and best practices, check out these links below:
https://www.neuconcrete.org/resources
https://www.shapedbyconcrete.com/#roadmap-to-carbon-neutrality
https://materialspalette.org/concrete/
DES does not endorse these products and technologies.
This blog post originates from a low-carbon design presentation by the DES sustainability team. Special thanks to Jyothsna Giridhar and Waibun Lee for some of the content materials and low-carbon concrete research.
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