A Carbon Negative Paving Block to Tackle Scope 3 Emissions
Deploying scalable carbon negative and carbon neutral materials can drastically reduce upfront carbon in the buildings and construction. Our materials choices — both big and small — can make our 2050 climate goals a reality.
How Built Environments Can Meet The Climate Challenge
“A quarter of a building’s emissions are locked in on the first day the occupants walk through the front doors. Every project team gets just one shot to reduce the upfront carbon of their next building.”
— Jorge Chapa, GCBA
The buildings and construction sector makes an outsized contribution to global carbon emissions with almost 40% of all energy-related global greenhouse emissions coming from built environments. Our most widely used construction materials — cement and steel — are two of the most significant sources of material related emissions, with cement manufacture responsible for 7% of global carbon emissions. With global building stock expected to double, the World Green Building Council (WGBC) identifies decarbonisation of the built environment as one of the most cost effective ways to mitigate climate change. The WGBC’s Net Zero Carbon Buildings Commitment aims to halve emissions produced by the building and construction sector by 2030 and totally decarbonise by 2050.
By 2030, all new buildings, infrastructure and renovations will have at least 40% less embodied carbon with significant upfront carbon reduction, and all new buildings are net zero operational carbon.
By 2050, new buildings, infrastructure and renovations will have net zero embodied carbon, and all buildings, including existing buildings must be net zero operational carbon.
Tackling embodied carbon — the greenhouse-gas (GHG) emissions associated with materials and construction processes through the lifecycle of a building — will be key to meeting these targets.
Scope 3 Emissions and Embodied Carbon
Embodied carbon refers to the greenhouse gas emissions associated with the manufacturing, transportation, use, and disposal of building materials used in construction. The Greenhouse Gas Protocol Corporate Accounting and Reporting Standard splits GHG emissions into three scopes:
Scope 1 emissions are from a company’s operations that are under a facility’s direct control, e.g., on-site fuel combustion;
Scope 2 emissions are from usage of electricity, steam, heat and/or cooling purchased from third parties; and
Scope 3 emissions are upstream and downstream value chain emissions, including upstream supply chain emissions from purchased products, transport emissions, and business travel and downstream emissions from transport of products, usage of sold products and product disposal.
Upfront or “cradle-to-gate” embodied carbon refers to embodied carbon impacts up to the point of purchasing, and are therefore accounted as scope 3 emissions. These are carbon emissions that have already been released into the atmosphere before the building is occupied or the infrastructure begins operation.
At the asset level, upfront carbon will be responsible for half of the entire carbon footprint of new construction between now and 2050, consuming a large proportion of the world’s remaining carbon budget. As operational carbon (energy to heat, cool and power buildings) is reduced, embodied carbon and Scope 3 emissions will continue to grow in importance as a proportion of total emissions.
In addition to the fossil-fuel based, carbon-intensive manufacturing processes of cement and steel, traditional building materials don’t have the ability to remove carbon from the environment. Even if emissions are minimised during construction, the carbon emitted by the building through its lifecycle remains positive. An effective material solution straddles multiple objectives, not only minimising emissions during production and transportation, but also minimising carbon emissions through its lifecycle.
The Innovation Behind Our Carbon Negative Paving Block
“Our Carbon Negative Paving Block can help reduce Hong Kong’s carbon footprint by up to 10%. Compared to a business-as-usual concrete paving block in Hong Kong, we’ve successfully reduced 110% of embodied carbon to create a carbon negative block. Our approach removes carbon dioxide (by up-cycling exhaust gas from industries, which would have otherwise gone into the atmosphere) through a new carbon reactive cementitious material, and an innovative carbon curing technique.”
— Antonio Ng, CEO Formwork IO
To tackle Scope 3 emissions, most green building products on the market today fall into three broad categories; some contain a high percentage of recycled content, some emit less carbon, and a few others absorb and remove carbon. Formwork IO offers a radical alternative, the Carbon Negative Paving Block combines all three attributes into one product.
In collaboration with Nano Advanced Material Institute and the Hong Kong Polytechnic University, we have successfully reduced 110 percent of the embodied carbon to go beyond zero. Through the R&D process, we were able to design out as much as 90 percent of the embodied carbon in our paving block. For the remaining 20 percent, we developed an innovative carbon removal technology that mineralises and permanently locks away carbon dioxide during production. Over 60 percent ingredients are upcycled from industrial wastes and concrete from demolition. The paving block can withstand over 30 MPa in compressive strength.
In comparison, a typical concrete paving block in Hong Kong represents around 1.043 kg CO2 e per unit (100 mm x 200 mm x 60 mm, weighing 3.5 kg). Through our circular lifecycle design approach, we have designed out about 92% of the embodied carbon from 1.043 to 0.075 kg CO2 e per unit. Through carbon removal, we are able to further remove another 18% to reach -0.102kg CO2 e per unit. The final result comes in at -0.102 kg CO2 e per unit, -28.641 kg CO2 e per ton, -63.565 kg CO2 e per m3.
Our life cycle assessment result issued by Hong Kong Polytechnic University certifies Formwork IO’s carbon-dioxide cured paving block as carbon negative, sequestering more carbon dioxide than it emits.
While carbon emissions are a global issue, embodied carbon is region specific. Materials that have a small carbon footprint in one region could entail a larger carbon footprint in another geography. Formwork IO’s Carbon Negative Paving Block was developed with regional supply chains and scalable volumes to ensure the life cycle emissions of our products are minimised.
We Need Bold Leaders to Enact Meaningful Change
The human and environmental impacts of climate change are becoming increasingly hard to ignore. As architects and engineers, property developers and asset managers, we now have a realistic chance of transforming Hong Kong’s urban landscape. Our Carbon Negative Paving Block can help reduce Hong Kong’s carbon footprint by up to 10%. As leaders in our industry and inhabitants of our planet, we recognise that changing our materials choices will be critical to helping decarbonise our energy-intensive sector. The time to act is now.