embedded emissions
{{Short description|Measure of greenhouse gas emissions}}
{{use dmy dates |date=May 2022}}
{{for|the related concept in relation to energy|embedded energy}}
File:CO₂_emissions_embedded_in_global_trade,_OWID.svg
One way of attributing greenhouse gas emissions is to measure the embedded emissions of goods that are being consumed (also referred to as "embodied emissions", "embodied carbon emissions", or "embodied carbon"). This is different from the question of to what extent the policies of one country to reduce emissions affect emissions in other countries (the "spillover effect" and "carbon leakage" of an emissions reduction policy). The UNFCCC measures emissions according to production, rather than consumption.{{cite web
|date=March 10, 2010
|title=House of Commons, minutes of evidence, taken before the Environmental Audit Committee, International Climate Change Negotiations, Rt Hon Edward Miliband MP, Mr Peter Betts and Ms Jan Thompson. Reply to Q39
|author=UK Parliament
|publisher=UK Parliament website
|url=https://publications.parliament.uk/pa/cm200910/cmselect/cmenvaud/uc446-i/uc44602.htm
|access-date=2010-04-05}} Consequently, embedded emissions on imported goods are attributed to the exporting, rather than the importing, country. The question of whether to measure emissions on production instead of consumption is partly an issue of equity, i.e., who is responsible for emissions.{{cite web
|year=2001
|title=Decision-making Frameworks. In: Climate Change 2001: Mitigation. Contribution of Working Group III to the Third Assessment Report of the Intergovernmental Panel on Climate Change (B. Metz et al. Eds.)
|publisher=Cambridge University Press, Cambridge, U.K., and New York, N.Y., U.S.A.
|author=Toth, F.L.
|url=http://www.ipcc.ch/publications_and_data/publications_and_data_reports.htm
|access-date=2010-01-10
|display-authors=etal
|archive-date=2018-10-05
|archive-url=https://web.archive.org/web/20181005032403/http://www.ipcc.ch/publications_and_data/publications_and_data_reports.htm
|url-status=dead
}}
The 37 Parties listed in Annex B to the Kyoto Protocol have agreed to legally binding emission reduction commitments. Under the UNFCCC accounting of emissions, their emission reduction commitments do not include emissions attributable to their imports.{{cite web
|url=http://news.bbc.co.uk/1/hi/sci/tech/4542104.stm
|work=BBC News
|date=December 19, 2005
|title=Trade can 'export' CO2 emissions
|author=Black, R.
|access-date=2010-04-05}} In a briefing note, Wang and Watson (2007) asked the question, "who owns China's carbon emissions?".{{cite web
|url=http://www.tyndall.ac.uk/content/who-owns-chinas-carbon-emissions
|author=Wang, T. and J. Watson
|title=Who Owns China's Carbon Emissions? Tyndall Centre Briefing Note No. 23
|date=October 2007
|publisher=Tyndall Centre website
|access-date=2010-04-05
|archive-url=https://web.archive.org/web/20170202043318/http://www.tyndall.ac.uk/content/who-owns-chinas-carbon-emissions
|archive-date=2017-02-02
|url-status=dead
}} In their study, they suggested that nearly a quarter of China's CO2 emissions might be a result of its production of goods for export, primarily to the US but also to Europe. Based on this, they suggested that international negotiations based on within country emissions (i.e., emissions measured by production) may be "[missing] the point".
Recent research confirms that, in 2004, 23% of global emissions were embedded in goods traded internationally, mostly flowing from China and other developing countries, such as Russia and South Africa, to the U.S., Europe and Japan. These states are included in a group of ten, as well as the Middle East, that make up 71% of the total difference in regional emissions. In Western Europe the difference in the import and export of emissions is particularly pronounced, with imported emissions making up 20-50% of consumed emissions. The majority of the emissions transferred between these states is contained in the trade of machinery, electronics, chemicals, rubber and plastics.{{cite journal|title=Consumption-based Accounting of {{CO2}} Emissions|author=Davis, S.K. and K. Caldeira|journal=Proceedings of the National Academy of Sciences of the United States of America|date=March 2010|volume=107|issue=12|pages=5687–92|publisher=Proceedings of the National Academy of Sciences|doi=10.1073/pnas.0906974107|pmid=20212122|pmc=2851800|bibcode=2010PNAS..107.5687D|doi-access=free}}
Research by the Carbon Trust in 2011 revealed that approximately 25% of all {{CO2}} emissions from human activities 'flow' (i.e. are imported or exported) from one country to another. The flow of carbon was found to be roughly 50% emissions associated with trade in commodities such as steel, cement, and chemicals, and 50% in semi-finished/finished products such as motor vehicles, clothing or industrial machinery and equipment.{{cite web|url=http://www.carbontrust.com/resources/reports/advice/international-carbon-flows|title=International Carbon Flows|publisher=Carbon Trust|date=May 2011|access-date=12 November 2012|archive-date=1 August 2018|archive-url=https://web.archive.org/web/20180801094102/https://www.carbontrust.com/resources/reports/advice/international-carbon-flows/|url-status=dead}}
Embodied carbon in construction
The embodied carbon of buildings is estimated to count for 11% of global carbon emissions and 75% of a building's emissions over its entire lifecycle.{{Cite web|last=Berg|first=Nate|date=2021-02-04|title=Energy efficiency is no longer enough. This is the next big challenge for green building|url=https://www.fastcompany.com/90601015/energy-efficiency-is-no-longer-enough-this-is-the-next-big-challenge-for-green-building|access-date=2021-08-12|website=Fast Company|language=en-US}} The World Green Building Council has set a target for all new buildings to have at least 40% less embodied carbon.{{Cite web |last=Rubidge |first=Lloyd |date=2020-10-28 |title=Embodied Carbon: An Architect's View |url=https://positive-impact.africa/embodied-carbon-an-architects-view/ |url-status= |access-date=2021-08-12 |website=+IMPACT Magazine |language=en-ZA}}
A life-cycle assessment for embodied carbon calculates the carbon used throughout each stage of a building's life: construction, use and maintenance, and demolition or disassembly.{{Cite web|last=Westwood|first=Tom|date=2021-08-06|title=Why Embodied Energy is the Elephant in the Room|url=https://www.bristolhousingfestival.org.uk/blog/embodied-carbon|url-status=dead|access-date=2021-08-12|website=Bristol Housing Festival|language=en-US|archive-date=12 August 2021|archive-url=https://web.archive.org/web/20210812165535/https://www.bristolhousingfestival.org.uk/blog/embodied-carbon}}
Re-use is a key consideration when addressing embodied carbon in construction. The architect Carl Elefante is known for coining the phrase, "The greenest building is the building that is already built."{{Cite web|title=Embodied Carbon in Buildings conference speakers|url=https://www.architects.org/embodied-carbon-in-buildings-conference/embodied-carbon-in-buildings-conference-speakers?token=BNFByUeXeuJHhwoyKtg6cwboc08GDdKb|access-date=2021-08-12|website=Boston Society for Architecture|language=en}} The reason that existing buildings are usually more sustainable than new buildings is that the quantity of carbon emissions which occurs during construction of a new building is large in comparison to the annual operating emissions of the building, especially as operations become more energy efficient and energy supplies transition to renewable generation.{{Cite web |last=Architecture 2030 |title=New Buildings: Embodied Carbon |url=https://architecture2030.org/new-buildings-embodied/ |url-status= |access-date=2021-08-12 |language=en-US}}
Beyond re-use, and excluding material extraction, which often accounts for high levels of embodied carbon, there are two principal areas of focus in the reduction of embodied carbon in construction. The first is to reduce the quantity of construction material ('construction mass') while the second is the substitution of lower carbon alternative materials. Typically—where reduction of embodied carbon is a goal—both of these are addressed.
Often, the most significant scope for reduction of construction mass is found in structural design, where measures such as reduced beam or slab span (and an associated increase in column density) can yield large carbon savings.{{Cite web |author-link=Buro Happold |title=Embodied Carbon Sensitivity Study |url=https://www.istructe.org/IStructE/media/Public/Resources/case-study-embodied-carbon-routes-to-reduction-20200406.pdf}}
To assist material substitution (with low carbon alternatives), manufacturers of materials such as steel, steel re-bar, glulam, and precast concrete typically provide Environmental Product Declarations (EPD) which certify the carbon impact as well as general environmental impacts of their products.{{Cite web|date=2015-05-15|title=Embodied Energy and Carbon|url=https://www.ice.org.uk/knowledge-and-resources/briefing-sheet/embodied-energy-and-carbon|access-date=2021-08-12|website=Institution of Civil Engineers (ICE)|language=en}} Databases that aggregate the embodied carbon values from EPD's and other sources such as academic studies, provide the embodied carbon values of many materials in one location, however the number of variables included in calculating the embodied carbon of building materials makes the values in the databases difficult to compare. {{cite journal |last1=Vaughan |first1=Josephine |last2=Evans |first2=Rebecca |last3=Sher |first3=Willy |title=Embodied Carbon Inventories for the Australian Built Environment: A Scoping Review |journal=Buildings |date=2024 |volume=14 |issue=3 |page=840 |doi=10.3390/buildings14030840 |doi-access=free }}
Minimizing the use of carbon-intensive materials may mean selecting lower carbon versions of glass and steel products, and products manufactured using low-emissions energy sources. Embodied carbon may be reduced in concrete construction through the use of Portland cement alternatives such as Ground granulated blast-furnace slag, recycled aggregates and industry by-products. Carbon-neutral, carbon positive, and carbon-storing materials include bio-based materials such as timber, bamboo, hemp fibre and hempcrete, wool, dense-pack cellulose insulation, and cork.{{Cite web|last=Varriale|first=Fabrizio|date=2021-05-27|title=The other side of the coin: Understanding embodied carbon|url=https://www.rics.org/en-hk/wbef/megatrends/natural-environment/the-other-side-of-the-coin-understanding-embodiehttps://www.rics.org/en-hk/wbef/megatrends/natural-environment/the-other-side-of-the-coin-understanding-embodied-carbon/d-carbon/|url-status=|access-date=2021-08-12|website=RICS World Built Environment Forum}}{{Cite web|last1=Knopps|first1=Abigail|last2=Jain|first2=Diksha|title=Carbon-Positive Materials: No Longer Far-Fetched, Increasingly Available – My amast|url=https://amast.com/elementor-32898/|url-status=|access-date=2021-08-12|website=AMAST|date=14 December 2020 |language=en-US}}{{Cite web|last=Pak|first=Anthony|date=2020-11-01|title=Embodied Carbon: Key Considerations for Key Materials|url=https://www.canadianarchitect.com/embodied-carbon-key-considerations-for-key-materials/|url-status=|access-date=2021-08-12|website=Canadian Architect|language=en-US}}
A 2021 study focused on "carbon-intensive hotspot materials (e.g., concrete foundations and slab floors, insulated roof and wall panels, and structural framing) in light industrial buildings" estimated that a "sizable reduction (~60%) in embodied carbon is possible in two to three years by bringing readily-available low-carbon materials into wider use".{{Cite web|last=Kriegh|first=Julie|date=2021-02-17|title=Carbon-Storing Materials: Summary Report|url=https://carbonleadershipforum.org/carbon-storing-materials/|url-status=|access-date=2021-08-12|website=Carbon Leadership Forum|language=en-US}}
Embodied carbon policy and legislation
A variety of policies, regulations, and standards exist worldwide with respect to embodied carbon, according to the American Institute of Architects.{{Cite web|last=American Institute of Architects|date=2020-01-15|title=Policies for Embodied Carbon: An International Snapshot|url=https://www.architectmagazine.com/practice/policies-for-embodied-carbon-an-international-snapshot_o|url-status=|access-date=2021-08-12|website=Architect Magazine}}
Eight states introduced procurement policies related to embodied carbon in 2021: Washington, Oregon, California, Colorado, Minnesota, Connecticut, New York, and New Jersey.{{Cite web|last=Lewis|first=Meghan|date=2021-07-10|title=States Act to Reduce Embodied Carbon in Public Procurement|url=https://carbonleadershipforum.org/states-act-to-reduce-embodied-carbon/|url-status=|access-date=2021-08-12|website=Carbon Leadership Forum|language=en-US}}
In Colorado, HB21-1303: Global Warming Potential for Public Project Materials (better known as "Buy Clean Colorado") was signed into law July 6, 2021. The law uses environmental product declarations (EPDs) to help drive the use of low-embodied-carbon materials.{{Cite web|last=Rocky Mountain Institute|date=2021-07-22|title=Colorado Passes Embodied Carbon Legislation — The Most Important Climate Solution You've Never Heard of|url=https://cleantechnica.com/2021/07/22/colorado-passes-embodied-carbon-legislation-the-most-important-climate-solution-youve-never-heard-of/|url-status=|access-date=2021-08-12|website=CleanTechnica|language=en-US}}
"In Europe, embodied carbon emissions have been limited in the Netherlands since 2018, and this is scheduled to happen in Denmark, Sweden, France and Finland between 2023 and 2027."{{Cite web|last=Arnold|first=Will|date=2021-07-23|title=We need a Part Z to regulate embodied carbon|url=https://www.building.co.uk/comment/we-need-a-part-z-to-regulate-embodied-carbon/5112954.article|url-status=|access-date=2021-08-12|website=Building|language=en}}
"On May 10, 2023, Toronto became the first community in North America to require lower-carbon construction materials in new construction projects, limiting embodied carbon from new city-owned municipal building construction. New buildings must now limit upfront embodied emission intensity — emissions associated with manufacturing, transporting, and constructing major structural and envelope systems — to below 350 kg CO2e/m2."{{cite news |title=Toronto Limits Embodied Carbon in New City Buildings |url=https://www.theenergymix.com/2023/05/14/toronto-limits-embodied-carbon-in-new-city-buildings/ |access-date=15 May 2023 |publisher=The Energy Mix |date=14 May 2023}} The new requirements are currently voluntary for non-city-owned buildings.
See also
References
External links
- [https://www.architects.org/embodied-carbon-in-buildings-conference/conference-resources?token=BNFByUeXeuJHhwoyKtg6cwboc08GDdKb Resources: Embodied Carbon in Buildings], Boston Society for Architecture
- [https://www.aia.org/articles/70446-ten-steps-to-reducing-embodied-carbon Ten Steps Towards Reducing Embodied Carbon] {{Webarchive|url=https://web.archive.org/web/20230426011434/https://www.aia.org/articles/70446-ten-steps-to-reducing-embodied-carbon |date=26 April 2023 }}, The American Institute of Architects
- [https://carbon-positive.org/sessions/ Carbon Positive Reset! 1.5 °C 2020 Teach-In]
- [https://materialspalette.org/ Carbon Smart Materials Palette]
- [https://www.metsec.com/decarb/low-embodied-carbon-steel/ What is Low Embodied Carbon Steel] voelstapine Metsec
- [https://www.istructe.org/resources/guidance/making-your-steel-specification-more-sustainable/ Making your steel specification more sustainable] Institute of Structural Engineers
- [https://healthymaterialslab.org/material-collections/low-carbon-materials List of Low Embodied Carbon Materials] Healthy Materials Lab at Parsons School of Design
Category:Climate change policy
Category:Greenhouse gas emissions