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Methodologies
Technical specifications and calculation frameworks for evaluating avoided emissions through wood product substitution.
Technical specifications and calculation frameworks for evaluating avoided emissions through wood product substitution.
General
Forest Tools
Harvested Wood Product Tools
Version 1.0, updated September 2026
The Embodied Carbon Tool enables users to estimate manufacturing greenhouse gas emissions from forest products. The tool uses geographically relevant data from verified Life Cycle Assessments (LCAs) or Environmental Product Declarations (EPDs). The methods that underlie the embodied carbon tool are largely based on the quantification approaches published in the USDA Entity Guidelines Chapter 5: Methods for Managed Forest Systems (Murray et al. 2024) Section 5.2.2. LCA Quantification of HWP Emissions (Cradle to Gate, From Forest to Product Manufacturing Gate) (herein after referred to as the “Entity Guidelines”) .
CCF: Hundred cubic feet
CO2e: Carbon dioxide equivalent
CORRIM: The Consortium for Research on Renewable Industrial Materials
DF: Displacement factor
EC: Embodied Carbon
ECF: Embodied Carbon Factor
ECFR: Embodied Carbon Factor by Region
EPD: Environmental Product Declaration
IPCC: Intergovernmental Panel on Climate Change
ISO: International Organization for Standardization
GWP: Global Warming Potential
HWP: Harvested Wood Product(s)
LCA: Life Cycle Assessment
Metric tonnes: Unit of weight equal to 1,000 kilograms (2,204.6 pounds), or approximately 1.102 short tons (t)
MBF: Thousand board feet
MDF: Medium Density Fiberboard
MSF: Thousand square feet
m3 : Cubic meters
MCF: Thousand cubic feet
NC: North Central (US Region)
NE: Northeast (US Region)
NLS: Northern Lake States (US Region)
PWE: Pacific Northwest, East side (US Region)
PWW: Pacific Northwest, West side (US Region)
PSW: Pacific Southwest (US Region)
RM: Rocky Mountain (US Region)
RMN: Rocky Mountain North (US Region)
RMS: Rocky Mountain South (US Region)
SC: South Central (US Region)
SE: Southeast (US Region)
U.S.: United States of America
USDA: United States Department of Agriculture
The data applied within the Embodied Carbon Pools reflects cradle-to-gate embodied carbon limited to U.S. forests and products, as illustrated in Figure 1 below.
Figure 1: Generic Presentation of Life Cycle Stages of HWPs in LCA Studies. Source: USDA Entity Guidelines, Quantifying greenhouse gas fluxes in agriculture and forestry: Methods for entity-scale inventory, Technical Bulletin 1939, 2nd ed., Chapter 5 (2024) (Section 5-B.2.3 LCA Method Overview and Demonstration).
The sources and sinks of greenhouse gasses (GHG) included within the Embodied Carbon Tool include:
The global warming potential (GWP) values in the Displacement Factor Tool are cradle-to-gate, meaning they cover emissions up until the factory gate (see Figure 1). Thus they do not by themselves represent use, end-of-life, landfill storage or later emissions.
Specifically, the GWP values are based on the A1–A3 “product-stage” life-cycle modules as defined in ISO 21930, which include the following:
The Embodied Carbon Tool was developed to provide users with the comprehensive suite of published embodied carbon data on wood products in the U.S., derived from either third-party verified EPDs or LCAs. Product or manufacturer EPDs are aggregated into four regions in the U.S., which is currently the most granular assessment of industry-wide embodied carbon information.
In some cases, there is no embodied carbon information available for a specific region/product because the product is either not made in that region or published life cycle assessments are not available to include in the database. In these cases, the Embodied Carbon Tool applies more general National U.S. or North American data.
The data are sourced from third party verified EPDs or published LCAs listed in Annex 3.
Uncertainty in the Embodied Carbon Tool’s outputs primarily arise from limitations in the underlying data. Specifically, these limitations include:
The Embodied Carbon Tool offers users two analysis pathways:
Based on the selected pathway, the tool delivers the cradle-to-gate embodied carbon values per inputted unit, separated into the A1 (raw material supply), A2 (transportation), and A3 (manufacturing) modules, following the construction works life cycle stages as defined in ISO 2017.
This entry point enables users to select a primary product for which to estimate the amount of carbon embodied by its use. User data inputs include:
Product: This is a primary or secondary wood product made in the U.S. Users input a volume of material in units that correspond to the default unit provided in the drop-down menu. Users can also select which region the product is derived from one of four regions in the US: Coast, Rocky Mountain, South, North. If there is no regional specific embodied carbon data for a product, users may also select National or North America as options.
Provider: This is the author or owner of the EPD or LCA report.
Production Region: Region-specific EPDs have been separated based on the four regions covered by AWC’s softwood lumber and Glulam EPDs (see Figure 2 below). Ten states do not have any mills represented in the AWC surveys (gray states in Figure 2), and therefore they were assigned to regions with similar product sourcing and utilization profiles. North Dakota, South Dakota, Nebraska, and Kansas were placed in the North Region and Wyoming, Colorado, Utah, Nevada, Arizona, and New Mexico were combined with the Inland Northwest to form the Rocky Mountain Region.
Figure 2: Product pathway regions.
Material Amounts: Users enter a quantity in the units that corresponds to the selected product default unit corresponding to their EPD or LCA report, which is mostly in units of cubic meters (m3).
This entry point enables users to estimate the embodied carbon within material removed from a forest. User data inputs include:
Region: Users select from one of eight regions (see Figure 3):
These regions are based on Smith et al. (2006) regional delineations as described in Figure 1 within that publication, but modified to match those presented in Smith et al. (2006) Table D6. Specifically, the Northern Lake States (NLS) and Northern Prairie States (NPS) are combined to form NC (North Central) and the Rocky Mountain North (RMN) and Rocky Mountain South (RMS) are combined to form a single Rocky Mountain region (RM). Figure 3 shows the adapted regional delineation applied in the FACT Displacement Factor and Embodied Carbon Tools.
Figure 3: Roundwood allocation regions. Adapted from Smith et al. (2006) to reflect data resolution in Smith et al. (2006) Table D6. Pacific Northwest, West (PNW); Pacific Northwest, East (PWE); Pacific Southwest (PSW); Rocky Mountain (RM); North Central (NC); South Central (SC); Northeast (NE); Southeast (SE).
Log Type: A user can enter harvest amounts separately for softwood and hardwood. If a user knows whether the log is considered a sawlog or pulpwood it can enable the “separate sawlog/pulpwood” toggle.
Harvest Quantity: A user enters the volume of harvested log that leaves the site (e.g. is delivered to a mill) corresponding to the log type selected. The user can choose between the following common log units: BF, MBF, CF, CCF, m3, short ton, metric ton.
Fiber Flow: The default values are based on Smith et al (2006) Table D6. A user can override these values with more granular data as long as they still sum to 100%. For example, California, Washington, and Oregon specific fiber flows can be found in the CALFire HWP Carbon Model, HWP Data Visualization under “existing data”: https://github.com/jeremygroom/HWP-C-vR/tree/main/HWP%20Data/ExistingData
After the Embodied Carbon Tool processes the user-supplied data, summary metrics and graphical outputs are presented in the user interface. Those corresponding to each of the two analysis pathways the Embodied Carbon Tool includes are presented below.
Summary metrics:
Graphical outputs:
Figure 4: Bar Chart showing total cradle to gate carbon emissions by life cycle modules
Figure 5: Table showing embodied carbon per unit product
Summary metrics:
Graphical outputs:
Figure 6: Bar chart displaying cradle-to-gate carbon emissions by life cycle modules.
Figure 7: Table showing total embodied carbon by region and product
The data used to create the ratios of harvested log to primary product are from Smith et al. (2006) Table D6.
The non-structural panels in Smith et al (2006) Table D6 were further broken out into particleboard, MDF, hardboard, and fiberboard based on the annual production reported in CORRIM LCA reports for each of these products, and then reallocated using the weighted average across the allocation fractions for nonstructural products (see Table 7 from CORRIM report).
Table 2: “Table 7” from CORRIM’s final report to U.S. Endowment representing the re-allocation of nonstructural panels
Table 3: Proportion of total roundwood (softwood/hardwood) in a region converted to a primary wood product.
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Users are given the option to override the default values with their own numbers as long as they add up to 100%. For example, users from CA, WA, and OR may want to use specific values that can be derived from TPO data HWP-C-vR/HWP Data/ExistingData at main · jeremygroom/HWP-C-vR · GitHub and found in the Harvested Wood Products Model V.r (HWP Data Visualization).
At the product level, embodied carbon results are presented based on the user- specified products and quantities and then summed. A carbon factor is also calculated representing the ratio of product embodied carbon divided by the amount of carbon stored in the product. Calculation steps are summarized below.
Equation EC-1: Total Product Embodied Carbon
The embodied carbon factor of a product is the ratio of embodied carbon (GWPFOSSIL) divided by the carbon stored in the product as CO2.
Equation EC-2: Product Embodied Carbon Factor
Using the data in Table 3 provided as input into Equation EC-3, an ECFR is determined for each region, species group (hardwood and softwoods), and roundwood type (sawlog and pulpwood) as follows:
Equation EC-3: Embodied Carbon Factor by Region (ECFR) Calculation for softwood or hardwood
The expanded equation for one region_logtype (e.g. PC SW SL) is:
ECF_region_logtype = (α_SWLumber × ECF_SWLumber )
+ (α_HWLumber × ECF_HWLumber )
+ (α_SWPlywood × ECF_SWPlywood )
+ (α_HWPlywood × ECF_HWPlywood )
+ (α_OSB × ECF_OSB )
+ (α_Particlbd × ECF_Particlbd )
+ (α_MDF × ECF_MDF )
+ (α_Hardboard × ECF_Hardboard )
+ (α_Fiberboard × ECF_Fiberboard)
+ (α_OtherIndus × ECF_OtherIndus)
+ (α_WoodPulp × ECF_WoodPulp )
Where:
α = Sourced from Table 3.
Region = (NE,NC,SE,SC,RM,PNWW,PNWE,PSW)
Logtype = SW (softwood) HW (hardwood) SL (sawlog) PW (pulpwood)
Note: “Other industrial products” represents the average embodied carbon results from the softwood lumber, hardwood lumber, softwood plywood, hardwood plywood, particleboard, OSB, MDF, hardboard, and fiberboard in the region.
Equation EC-4: Downstream Embodied Carbon
The biogenic carbon in the harvested log is converted from the user’s input unit (weight or volume) using the FACT Unit Conversion Methodology.
CORRIM Embodied Carbon Tool Progress Final Report 12.19.24 Appendix A
ISO. 2017. Sustainability in buildings and civil engineering works- Core rules for environmental product declarations of construction products and services. International Organization for Standardization. Second edition (ISO 21930:2017-07) 80pp.
Forest Products Laboratory. (2021). Wood Handbook: Wood as an Engineering Material (General Technical Report FPL–GTR–282). USDA Forest Service.
Murray, L.T., C. Woodall, A. Lister, K. Stockmann, H. Gu, Urbanski, S., Riley, K., Greenfield E., et al. 2024. Chapter 5: Quantifying greenhouse gas sources and sinks in managed forest systems. In Hanson, W.L., C. Itle, K. Edquist. (eds.). Quantifying greenhouse gas fluxes in agriculture and forestry: Methods for entity-scale inventory. Technical Bulletin Number 1939, 2nd edition. Washington, DC: U.S. Department of Agriculture, Office of the Chief Economist.
Smith, James E.; Heath, Linda S.; Skog, Kenneth E.; Birdsey, Richard A. 2006. Methods for calculating forest ecosystem and harvested carbon with standard estimates for forest types of the United States. Gen. Tech. Rep. NE-343. Newtown Square, PA: U.S. Department of Agriculture, Forest Service, Northeastern Research Station. 216 p.
Smook, G. A. (2016). Handbook for Pulp and Paper Technologists (4th ed.). TAPPI Press.
U.S. Endowment. 2024. CORRIM Embodied Carbon Tool Progress Report Final Report 12192024
Terms specific to this methodology are defined below. See the main FACT Glossary for general terms and for the sources from which definitions are adapted.
Allocation: Partitioning the input or output flows of a process or a product system between the product system under study and one or more other product systems. In wood products accounting, allocation determines how processing emissions are apportioned between primary products such as lumber and the coproducts generated alongside them, including chips, sawdust and mill residues. (Adapted from ISO 14040:2006/Amd 1:2020)
Biogenic carbon: Carbon contained in or originating from living or recently living biological material, such as trees, other vegetation, soils and wood products. It is part of the natural carbon cycle and distinct from fossil carbon released from coal, oil and natural gas.
By-product: A secondary or incidental product generated from a process whose primary purpose is to produce another product.
CO2e (Carbon dioxide equivalents): A common unit that allows the climate effects of different greenhouse gases to be compared and summed. The quantity of a greenhouse gas is multiplied by its global warming potential (GWP), which expresses its warming effect timbrelative to carbon dioxide over a specified time horizon, conventionally 100 years. The result is reported as the mass of CO₂e that would produce an equivalent climate effect. (Adapted from ISO 14067)
Cradle-to-gate: A system boundary that covers production from raw material extraction through manufacturing, ending when the product leaves the factory gate. It includes raw material supply and upstream production, transport to the factory, and manufacturing. It excludes distribution, use, and end-of-life. (Adapted from ISO 21930:2017)
Declared unit: The quantity of a construction product for use as a reference unit in an EPD based on LCA, for the expression of environmental information needed in information modules. When the precise function of the product or scenarios at the construction works level is not stated, or is unknown, a declared unit may be used instead of the functional unit. (Adapted from ISO 21930:2017)
Embodied Carbon: The greenhouse gas emissions associated with producing a material or product.
In FACT, embodied carbon is evaluated on a cradle-to-gate basis, including emissions associated with raw material extraction or harvest, transportation of those materials to the manufacturer and manufacturing of the finished product. It does not include emissions associated with product use, transportation beyond the manufacturing gate, or end-of-life treatment. Embodied carbon also does not include carbon stored in the product itself. (Adapted from American Wood Council, AWC's LCA, EPDs, GWP, and Other Abbreviations Explained)
Life Cycle Assessments (LCA): A method for systematically evaluating the environmental inputs, outputs, and potential impacts associated with a product or process over a defined portion of its life cycle. The scope of an LCA depends on the system boundary selected. In FACT, LCA results are used on a cradle-to-gate basis, covering stages from raw material extraction or harvest through production of the finished material or product.
Life Cycle Inventory (LCI): A phase of life cycle assessment involving the compilation and quantification of inputs and outputs for a product throughout its life cycle. (Adapted from ISO 14040:2006/Amd 1:2020)
Life Cycle Impact Assessment (LCIA): A phase of life cycle assessment aimed at understanding and evaluating the magnitude and significance of the potential environmental impacts for a product system throughout the life cycle of the product. (Adapted from ISO 14040:2006/Amd 1:2020)
Product Categories:
Lumber softwood: Construction lumber is wood that has been sawn from logs and dressed or surfaced to standard dimensions for use in structural and general building applications, such as framing walls, floors, and roofs. Commonly produced from softwood species such a pine, fir, spruce, and hemlock. (Source: Forest Products Laboratory. (2021). Wood Handbook: Wood as an Engineering Material (General Technical Report FPL–GTR–282). USDA Forest Service.)
Dimension lumber, studs cut from a round log. Conversions based on a nominal 2x6, actual 1.5 x 5.5.
Plywood softwood: Plywood is an engineered wood panel product made by bonding together thin sheets of wood veneer (ply) with adhesive under heat and pressure. The grain direction of each ply is typically rotated 90 degrees relative to the adjacent layers. (Source: Wood Handbook, chapter 10)
Softwood veneers bonded together with adhesive and cured under heat and pressure. Veneers are peeled from round log.
Particleboard: An engineered wood product made by compressing wood particles—such as wood chips, sawmill shavings, or sawdust—together with a synthetic resin or other suitable binder, then hot-pressing the mixture into flat sheets. (Source: Source: Forest Products Laboratory. (2021). Wood Handbook: Wood as an Engineering Material (General Technical Report FPL–GTR–282). USDA Forest Service, chapter 10)
Medium density fiberboard (MDF): An engineered wood product made by breaking down softwood or hardwood residuals into fine wood fibers, combining them with a wax and resin binder, and forming the mixture into panels under heat and pressure. (Source: Source: Forest Products Laboratory. (2021). Wood Handbook: Wood as an Engineering Material (General Technical Report FPL–GTR–282). USDA Forest Service, chapter 10)
Oriented strand board (OSB): An engineered wood panel product made by compressing layers of thin, rectangular wood strands together with a waterproof resin binder under heat and pressure. The strands in each layer are aligned, or "oriented," in a specific direction, and successive layers are typically arranged perpendicular to one another. (Source: Source: Forest Products Laboratory. (2021). Wood Handbook: Wood as an Engineering Material (General Technical Report FPL–GTR–282). USDA Forest Service, chapter 10)
Usually made of low density hardwood species but can be made with softwood species.
Hardboard: An engineered wood product made by breaking wood down into fibers and then reconstituting them into panels under heat and pressure, without adding a synthetic binder in the traditional sense—the panel is typically held together through the natural adhesive properties (lignin) of the wood fibers themselves, activated during hot pressing. (Source: Source: Forest Products Laboratory. (2021). Wood Handbook: Wood as an Engineering Material (General Technical Report FPL–GTR–282). USDA Forest Service, chapter 10)
Fiberboard: Cellulosic Fiberboard falls within the engineered wood products category or wood insulation board in which wood elements of varying sizes are held together by an adhesive bond using a vegetable starch binder. Used in building constructions for roofing substrates, structural wall sheathing, sound-deadening board, and other specialty-materials in North America.
Other industrial products: In the Embodied Carbon Tool, this category is represented as the average of the values for the known product categories.
Wood pulp: A fibrous material produced by mechanically or chemically separating wood into its constituent cellulose fibers, derived from either hardwood or softwood species (or a blend of both), each contributing different fiber characteristics—softwoods typically yielding longer fibers that provide strength, and hardwoods yielding shorter fibers that improve smoothness and printability. Depending on further processing, wood pulp may be classified as unbleached, retaining its natural brownish color and higher lignin content, or bleached, in which the pulp is treated to remove residual lignin and impurities, producing a whiter, purer fiber suited for higher-grade paper products. (Source: Smook, G. A. (2016). Handbook for Pulp and Paper Technologists (4th ed.). TAPPI Press.)
Product Category Rules (PCR): A set of specific rules, requirements and guidelines for the development of type III environmental declarations for one or more product categories. (Adapted from ISO 14025)
System boundary: The set of criteria determining what is included in, and excluded from, an assessment.
In greenhouse gas inventory accounting, the system boundary specifies which activities, greenhouse gases and carbon pools are included. It operates alongside spatial boundaries, which delimit the geographic area assessed; sector boundaries, which determine where emissions and removals are reported; and temporal boundaries, which establish the accounting period. (Adapted from Murray et al. 2024)
In life cycle assessment, the system boundary specifies which processes and life cycle stages are included in the product system. For example, a cradle-to-gate boundary includes raw material extraction or harvest through product manufacturing. (Adapted from ISO 14044/Amd1:2017/Amd2:2020.)
EPDs are regularly updated, and therefore future iterations of the Embodied Carbon Tool will seek to incorporate them based on the following criteria:
Figure 8: Declaration Page Example
Every EPD is standardized, to a degree, as there are required sections per ISO 14025 Environmental labels and declarations – Type III environmental declarations – Principles and procedures standard. The “owner” of the EPD has the flexibility to add additional information about the product based on their objectives. Below are some key elements to look for in an EPD.
For example, in Table 4 below, the values on the orange line are the EC values that would be entered into the Embodied Carbon database. These values are for Inland Northwest Softwood Lumber.
Table 4: Example Cradle to Gate LCIA Results for 1m3 of Inland Northwest softwood lumber - Absolute Basis (AWC 2024, INW-EPD-Final2-07222025.pdf) | ||||
|---|---|---|---|---|
Core Mandatory Impact Indicator | Total | A1 | A2 | A3 |
GWPTOTAL [kg CO2 eq] | 71.35 | (2,004.51) | 11.07 | 2,064.79 |
GWPBIOGENIC [kg CO2 eq] | 0.00 | (2,024.63) | 0.00 | 2,024.63 |
GWPFOSSIL [kg CO2 eq] | 71.35 | 20.12 | 11.07 | 40.16 |
ODP [kg CF-11eq] | 7.74E-07 | 1.26E-07 | 1.85E-08 | 6.30E-07 |
AP [kg SO2 eq] | 0.74 | 0.42 | 0.06 | 0.26 |
EP [kg N eq] | 0.23 | 0.03 | 0.00 | 0.20 |
SFP [kg O3 eq] | 23.82 | 12.10 | 1.76 | 9.95 |
FFD [MJ, surplus] | 121.15 | 35.07 | 20.81 | 65.27 |
ADPFOSSIL [MJ, LHV] | 920.70 | 234.14 | 138.54 | 548.01 |
The carbon (C) storage in product values reflects the amount of carbon, displayed as CO2e, that is physically stored in the product at the time of production. This is taken directly from the product’s EPD (if they have one), which tracks biogenic carbon as it enters the product system as a removal (negative value)(e.g., a log) and leaves the system as an emission from the product and coproducts (positive value). The table below is required in all wood-based EPDs and normally found after the reporting of the impact indicators (table above). If the EPD scope is cradle-to-gate, the biogenic carbon will be reported under A1-A3, A5, C3/C4, and the full value of the “carbon storage in product” will be reported as an emission under C3/C4. In the case of Inland Northwest Softwood Lumber (see Table below), the carbon storage is 863.02 kg CO2e = Biogenic carbon emission from the product.This is the carbon stored in the final product.
Table 5: Example Biogenic Carbon Inventory Parameters for Inland Northwest Softwood Lumber (AWC 2024, INW-EPD-Final2-07222025.pdf) | |||||||
|---|---|---|---|---|---|---|---|
A1 | A2 | A3 | A5 | C3/C4 | Total | ||
Biogenic Carbon Removal from Product | BCRP [kg CO2] | (2,025.76) | 0.00 | 0.00 | 0.00 | 0.00 | (2,025.76) |
Biogenic Carbon Emission from Product | BCEP [kg CO2] | 0.00 | 0.00 | 934.65 | 0.00 | 863.02 | 1,797.68 |
Biogenic Carbon Removal from Packaging | BCRK [kg CO2] | 0.00 | 0.00 | (1.72) | 0.00 | 0.00 | (1.72) |
Biogenic Carbon Emission from Packaging | BCEK [kg CO2] | 0.00 | 0.00 | 0.00 | 1.72 | 0.00 | 1.72 |
Biogenic Carbon Emission from Combustion of Waste from Renewable Sources Used in Production | BCEW [kg CO2] | 0.00 | 0.00 | 228.08 | 0.00 | 0.00 | 228.08 |
For calculating carbon content of wood, use the oven dry, 0% MC density of the product. In this example of Inland northwest softwood lumber, the oven dry density is 470.74 kg/m3. Wood contains about 50% carbon, therefore, 470.74 kg/m3 of softwood lumber contains about 235.37 kg/m3 of carbon. Because we want to compare the carbon storage in wood to the carbon emissions released (EC), convert the carbon in the wood to CO2. This is done by multiplying the carbon content of the product, 235.37 kg/m3, by the molecular weight ratio of carbon dioxide to carbon, which is 44/12. Therefore, 235.37 kg/m3 X 44/12 = 863.02 kg of CO2 in the product.