Understanding Embodied Emissions

Decarbonizing societal infrastructure, including computing, has emerged as a grand challenge for the 21st century, and thus has seen increasing research attention in recent years. Reducing the carbon emissions of societal infrastructure, whether it be a commercial building or cloud datacenter, generally has two important aspects: reducing operational emissions---the carbon emissions from day-to-day operations---and reducing embodied emissions---the carbon emissions from construction and deployment. These different types of emissions are formally defined for companies in the Greenhouse Gas Protocol (GHG) as (i) Scope 1 emissions, which represent a company's direct emissions, e.g., from directly burning fossil fuels, (ii) Scope 2 emissions, which represent a company's indirect emissions from purchasing and using energy, primarily in the form of electricity, and (iii) Scope 3 emissions, which are indirect emissions that result from all other upstream and downstream activities, such as from purchased goods and services. Collectively, Scopes 1 and 2 capture a company's operational emissions, while Scope 3 captures its embodied emissions.