Energy experts and leading developers and architects are increasingly paying attention to embodied carbon in buildings. Embodied carbon refers to the total amount of greenhouse gas emissions generated by burning fuels throughout a building’s life cycle, from raw material extraction to disposal. It includes emissions generated during mining, processing, manufacturing, transportation, and even waste management. Essentially, it is the energy “embodied” within the physical structure in the process of creating it. Embodied carbon should not be confused with operating carbon emissions, which refers to heating, cooling, illuminating and otherwise powering the building during its use.
The amount of embodied carbon depends on many factors, such as the type of fuel used in all the stages of the creation of the thing, the amount and type of materials selected, the distance and mode of transportation, method of disposal, and so on. It is usually expressed as an annualized amount calculated by dividing the total embodied carbon by the expected life of that physical product. Regarding buildings, larger houses have greater embodied energy than smaller ones, and very old Victorian structures we love in Newton have lower embodied energy than the less durable recent construction (though the latter have lower operating energy owing to the modern building methods).
All Things Produced Have Embodied Carbon Footprints
The concept of embodied carbon applies to all physical products in our daily lives: furnishings, clothing, toys, vehicles, appliances, books, including food. In other words, our consumption practices – what and how much we acquire — are an important contributor to our personal carbon footprint. How important? In the case of buildings, the annualized embodied carbon in many cases equals the operating carbon emissions.
In 2021, the Oregon Department of Environmental Protection calculated statewide carbon emissions in two ways. One included only the emissions generated within the state from direct use of fuels and electricity (territorial emissions). The second approach entailed adding up territorial emissions and embodied carbon in products consumed within the state but manufactured elsewhere; and subtracting products and fuels produced in Oregon but exported from the state (consumption-based emissions). The graph below compares the results over time.
Based on territorial emissions (green triangles), Oregon seemed to make some progress toward climate goals starting around the year 2000. But consumption-based emissions radically change the picture; the real carbon impact of Oregon has been relentlessly increasing since 1990 (black circles). In other words, consumption of products made outside the state is a large and growing contributor to the total carbon footprint of Oregon.
Targeting Local Energy Use Reduces Only a Part of Newton’s GHG Emissions
Traditionally, greenhouse gas emissions inventories, including the one developed by Newton Energy Commission in 2020, have covered only territorial emissions. If a product is imported from the outside of Newton – whether it is the neighboring municipality or China – its embodied carbon is not included in the calculations. On the other hand, the embodied carbon of the mass of products imported from China and other countries, is included in the inventories of those coutnires, even though they make them for us and do not use them within their national borders.
How big is the missing part of emissions in Newton? We do not know. Calculating consumption-based emissions is complicated and not reliable for small geographic areas such as Newton. But we do know some things about residents’ lifestyles that allow us to get a general idea.
It has been well established that carbon emissions of households –both embodied and operating– increase with household income. We also know that Newton has a high average income. The average size of residential homes is also large and is getting larger in new construction. These homes are filled with furnishings. Newton residents also travel a lot by air to remote destinations abroad (this is not counted in either territorial or embodied carbon, but it should). In short, Newton’s GHG emissions would be much greater than what the 2020 Inventory shows if it truly reflected the lifestyles and consumption patterns of its residents.
The policy implications of this reality for the municipality are unclear. But if we in Newton are to have an honest conversation about our collective responsibility toward the world and the Commonwealth, we need to include the topic of household consumption.
Halina Brown is Professor Emerita of the Environmental Science and Policy Program at Clark University and Chairperson Emerita of the Newton Energy Commission. She can be reached at HBrown@clarku.edu.
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