That was the vision that led the Skanska USA Commercial Development team and its industry partners to develop the Embodied Carbon in Construction Calculator (EC3), a tool for calculating and evaluating the carbon emissions embodied within a wide array of building materials. Launched in 2019, EC3 has been used on every Skanska USA commercial development project since 2020 to calculate possible reductions in carbon emissions. It is also rapidly transforming the wider US industry.
Details of more than 16,000 materials
While owners and operators have long been able to establish the operational carbon footprint of a building by analyzing energy consumption, it has been far more difficult to determine the level of embodied carbon in building materials.
EC3 relies on environmental product declaration (EPD) data to quantify the carbon footprint of more than 16,000 building materials ranging from concrete, steel and gypsum through to carpets and windowpanes. It is searchable by material performance requirements and design specifications, project location and global warming potential. The tool is open-source and free to use.
As well as listing conventional materials, EC3 lists lower-carbon alternatives which, in many cases, can be substituted without any loss of material performance and often for the same price. These can include various forms of lower-carbon concrete, in which materials such as slag and fly ash substitute a proportion of the cement. By using the tool at the design stage and by making appropriate material purchasing decisions, builders and designers have been able to make major reductions in the amount of embodied carbon in projects.
Take the case of our 1550 on the Green office tower, currently being constructed in Houston in the USA. Through the use of EC3, reductions were achieved in the embodied carbon in materials including aluminum, roofing material, carpeting and ceiling tiles. However, the largest carbon reduction have come from concrete and rebar. The foundation of the building, for example, was created using a concrete mix in which 55 percent of the cement was replaced by fly ash. The overall result of these efforts was a 34 percent reduction in carbon emissions from materials.
(It should be noted that the total embodied carbon figure for a building takes into account a range of carbon sources on top of carbon related to construction materials. Emissions from these sources accumulate throughout the building’s lifespan and include emissions related to things like maintenance during its working life, and demolition and disposal at the end of its life.)
Massive potential for carbon reduction
The potential carbon reductions from using EC3 are significant when you consider that about 230 billion square meters (2.4 trillion square feet) of floor area will be added to global housing stock between 2020 and 2060. Over the average life cycle of a new building, roughly half of its carbon will come from embodied carbon. Considering that materials used for construction are estimated to consume 75 percent of all new materials annually by volume, the case for reducing the embodied carbon in building materials is clear.
Work on EC3 began in 2016 through a project funded through Skanska’s Innovation Grant program. Working with the University of Washington’s Carbon Leadership Forum, Skanska’s Stacy Smedley established orders of magnitude around embodied carbon in building materials.
We then partnered with software developer C Change Labs to develop a solution that would enable the building industry to easily access and view carbon emissions data for construction material. Initial development was jointly seed-funded by a second Skanska Innovation Grant, and by Microsoft, a Skanska client.
In 2018, together with our co-creators, we made the decision that EC3 should be a free, open-source platform to be available to as many users worldwide as possible. Today thousands of designers, builders and building owners and operators use the tool, which is made available through Building Transparency, a US-based non-profit organization.