Product Carbon Footprint (Resource)

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[Compilation Overview]

Product Carbon Footprint

What is a Product Carbon Footprint?

A Product Carbon Footprint (PCF) is the sum of (cumulative, aggregate, total) greenhouse gas (GHG) emissions "produced or used" throughout the full life cycle (lifespan) of a good or service ("product"), including production, consumption and end-of-life treatment. It may include atmospheric carbon removal, if any, that is directly associated with producing, consuming the product and/or the end-of-life treatment of the product.[1][2]

Carbon Inventory

Every PCF prepares a greenhouse gas (GHG) inventory (see: Carbon inventory), which is a complete account of all greenhouse gas (GHG) emissions and removals associated with the product. In some cases, a PCF may only cover emissions over a portion of a product's lifespan, e.g., 'cradle-to-gate' (which includes emissions from raw material extraction/cultivation up the point that a product leaves the reporting company's factor gate, i.e., immediately following final production)[3], thus making it a partial lifecycle PCF; or a PCF may only includes certain greenhouse gases, e.g., exclusively Carbon dioxide (CO2), excluding, for example, Methane or Nitrous oxide, if any, which may result in the PCF not being standard compliant. Refer to Product Standard. In some instances, if other greenhouse gases account for an insignificant fraction of the total carbon inventory, they can be excluded while the PCF remains standard-compliant.

Life Cycle Assessment v. Product Carbon Footprint

A Life Cycle Assessment (LCA) involves assessing some or all environmental impacts, typically, for all life cycle stages associated with a product; as such, an LCA typically includes a GHG inventory. The following are available and detailed in the sub-section, Unit of measure, below: Global warming potential (GWP) conversion factors for the 200+ greenhouse gases in life; and The Big Three greenhouse gases, namely, Carbon dioxide (CO2), Methane (CH4), and Nitrous oxide (N2O).

Lifespan and Lifecycle stages

There are three widely recognized product life cycle accounting and reporting standards for "the measurement of GHG emitting processes, their origins, and their composition and amounts" over the full lifespan of a product. Accounting for all business activities and processes over the full lifespan of a product -- and associated emissions and removals -- is often complex and differs widely for various products and product-types.[4]

That said, the full lifespan of a product, as it concerns carbon and environmental impact accounting, can be classified into five life cycle stages. Each stage may have multiple processes associated, as per the process mapping (guideline). In short, the product life cycle stages -- using nomenclature from WC-Compliant assessments -- are as follows:

  1. Pre-manufacture -- including extraction of raw materials and pre-processing;
  2. Product manufacture -- including production and assembly;
  3. Product distribution -- including, packaging, shipping and storing, at distribution hubs and retail sites;
  4. Customer use -- including transporting products from retail sites to consumers and, often, emissions associated with using a final product, e.g., electricity to power laptops or smartphones, electricity to power washing machines and dryers for t-shirts or socks, and gasoline to power vehicles; and
  5. End-of-life (EOL) -- this can take the form of energy required to recycle, reuse and/or dispose of a product; and may include emissions associated with final product decomposition, depending on how the carbon inventory is prepared.

Carbon accounting

Two important concepts to be familiar with, as it concerns product life cycle carbon accounting and reporting, are: (1) accounting for emissions and removals separately, and (2) Carbon dioxide equivalent (CO2e) as the unit of measure. As it concerns emissions and removals, both GHG emissions into the atmosphere, and carbon removals from (out of) the atmosphere -- that are directly associated with a product, over the full life cycle of said product -- are included in the GHG inventory ("carbon inventory").[5][4]

Some emissions/(removals) are caused by activities and/or processes that are not directly associated with a product (e.g., they do not become the product, make the product, or directly transport the product), may nonetheless be allocated to the product carbon footprint (GHG Protocol Product Standard calls them "non-attributable processes), for example, capital equipment, overhead operations (e.g., air-conditioning, lighting), corporate activities (e.g., general and administrative activities), transporting a customers to the retail locations from which they purchase products, and/or transporting employees to and from work. For more, refer to upstream and downstream emissions in Scopes.[5]

Emissions

Emissions are likely the most straight-forward. Generally speaking, human-caused emissions result from (1) fossil fuels (when they're burned), (2) chemicals (when they react), (3) organic biomass (when we burn trees, plants, etc.), and, less widely discussed, (4) destruction of soil organic matter (SOM) (e.g., when topsoil is tilled, which often causes in increases in CO2 fluxes, i.e., releases, topsoil runoff, and/or other aerodynamic pressures). When it comes to product life cycle carbon accounting, as stated at the beginning of this section, emissions must be directly associated with a product to be included in a PCF Assessment or Life Cycle Assessment (LCA). For many if not most goods, most emissions originate from the combustion of fossil fuels (see: 'Historical carbon dioxide emissions' and 'Historical other greenhouse gases' in Remaining carbon budget).

Removals

Removals -- while they can be natural and human-caused, e.g., sequestration and carbon capture technology -- result from almost exclusively photosynthesis, and to a minor extent, from carbonation, especially with concrete; and may include other processes that absorb and/or capture carbon (C) from the atmosphere.[6] When it comes to product life cycle carbon accounting, as stated at the beginning of this section, removals must be directly associated with a product are to be included in a PCF Assessment or Life Cycle Assessment (LCA).

For example, carbon embedded in the wood (raw material) comprising a table (final product), can be considered a removal -- until the wood is finally discarded, and either is burned or left to decompose, both of which result in the embedded carbon being released (emitted) into the atmosphere. The carbon removal at the beginning of the product lifespan, and emissions at the end of the product lifespan, balance each other out (zero out). In this example, the removals associated with wood (biomass) is directly associated with the final product.[7]

Unit of measure: Carbon dioxide equivalent (CO2e)

The Big Three outlines the three most prevalent greenhouse gases; and Greenhouse gas conversion factors explains and details global warming potential (GWP) conversion factors.

Carbon dioxide (CO2) overwhelmingly accounts for most human-caused greenhouse gas (GHG) emissions. Since CO2 is the most prevalent on a 100+ year timescale and has the largest greenhouse effect, other non-CO2 GHGs are converted into the common unit, Carbon dioxide equivalent (CO2e), using conversion factors based on their global warming potential (GWP) relative to CO2 over a particular timeframe (e.g., 20-year, 100-year or 500-year). Global warming potential (GWP) conversion factors convert non-CO2 greenhouse gases (GHGs) into the equivalent measure of Carbon dioxide (CO2), thus yielding the CO2-equivalent (CO2e) measure of any GHG. For example, one metric ton of Methane (CH4) has around the same GWP as thirty metric tons of carbon dioxide (CO2), and is therefore represented as 30 MtCO2e. This is similar to converting monetary amounts of different currencies into a single base currency in order to compare them.

Carbon capture and offsets

Human-caused carbon capture, e.g., human-caused removals by carbon capture and storage (CCS) technologies, unless directly associated with product manufacture, are excluded from a PCF assessment or Life Cycle Assessment (LCA). In almost all instances, carbon offsets and avoided emissions are excluded from an assessment because both "occur outside the boundary of [a] product's life cycle."[5] Carbon capture and carbon offsets may be products in and of themselves, but they typically are not directly or indirectly associated with producing or consuming a product, and thus are excluded from a product carbon footprint. Typically, offset certificates are bought by producers or consumers to offset the carbon footprint of a product. For example, carbon captured by virgin forest (from which many carbon offsets are created), can be reported on separately, i.e., as a stand-alone product. Associating this carbon capture with another product, however -- that is in no way directly associated with said virgin forest -- is not in-line with internationally accepted product life cycle accounting and reporting standards.

Resources

The Compilation (Guideline) provides a basic outline of requirements for WC-Compliant PCF assessments -- including an outline of how to use the following guidelines when preparing an assessment:

  1. Streamlined PCF (Guideline)
  2. Product Standard PCF (Guideline)
  3. Streamlined (what does this term mean exactly?).
  4. Product Life Cycle Accounting and Reporting Standard (by GHG Protocol).

Other guides and books:

  1. Guide (free): Product Carbon Footprinting for Beginners.[3]
  2. Book (paid): Carbon Footprint Analysis.[4]
  3. Book (paid): The Handbook of Carbon Footprint Accounting.[8]

Select Wikipedia pages:

  • Carbon footprint [4]
  • Carbon accounting [5]
  • Life-cycle assessment (LCA); also called Cradle to Grave (C2G) [6]
  • Life-cycle cost analysis [7]
  • Life-cycle greenhouse gas emissions of energy sources [8]
  • End-of-life (product) (EOL) [9]
  • Cradle-to-cradle design [10]
  • Regenerative design [11]

References

  1. CarbonTrust, 2019. "Product Footprint Certification." Accessed 2019/10/20; Archived 2019/10/20.
  2. PCF World Forum, 2012. "PCF World Forum Executive Summary #1 'Product Carbon Footprint (PCF)'". Published on August 13, 2012. <https://issuu.com/thema1/docs/pcf_world_forum_executive_summary__1_product_carbo>. Accessed on April 4, 2020.
  3. 3.0 3.1 World Resources Institute (WRI) and World Business Council for Sustainable Development (WBCSD). Greenhouse Gas Protocol Product Life Cycle Accounting and Reporting Standard. September 2011. <https://ghgprotocol.org/product-standard>.[1] Cite error: Invalid <ref> tag; name ":3" defined multiple times with different content
  4. 4.0 4.1 4.2 Matthew John Franchetti and Defne Apul. Carbon Footprint Analysis: Concepts, Methods, Implementation, and Case Studies. CRC Press. Taylor & French Group, 2013.
  5. 5.0 5.1 5.2 World Resource Institute (WRI) and World Business Council for Sustainable Development (WBCSD). Greenhouse Gas Protocol Life Cycle Accounting and Reporting Standard. September 2011. <https://ghgprotocol.org/product-standard/>.[2]
  6. Note: Carbonation is when "CO2 diffuses into the pores of cement-based materials" and sequesters; it is highly dependent on the exposure time in the service (useful) life of concrete, which is typically assumed to be the average lifespan of a building (which some put at approximately 50 years). The figure could be as much as 43% of emissions from concrete being sequestered over the full life cycle of its use and reuse. Source: Xi, Fengming, Steven J. Davis, Philippe Ciais, Douglas Crawford-Brown, Dabo Guan, Claus Pade, Teimao Shi, Mark Syddall, Jie Lv, Lanzhu Ji, Longfei Bing, Jiaoyue Wang, Wei Wei, Keun-Hyeok Yang, Björn Lagerblad, Isabel Galan, Carmen Andrade, Ying Zhang, and Zhu Liu. "Substantial Global Carbon Uptake by Cement Carbonation." Nature Geoscience 9, no. 12 (2016): 880-83. <https//doi.org/10.1038/ngeo2840>.[3]
  7. While the three internationally recognized product life cycle accounting and reporting standards account for some classifications of embedded carbon (e.g., carbon in fruit/vegetable products that individuals consume) differently, i.e., the PAS 2050 excludes some embedded carbon in certain food products, generally speaking, the three standards include all emissions and removals directly associated with the product.
  8. Arnaud Brohé. The Handbook of Carbon Accounting. Greenleaf Publishing Limited, UK, 2016.