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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.
Forest Stand Carbon
Harvested Wood Product
The displacement factor tool enables users to evaluate the potential avoided emissions from using wood products instead of functionally equivalent alternative products and systems. The methods that underlie the displacement factor 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)(herein after referred to as the “Entity Guidelines”) Section 5.2.2. Avoided Emissions or Emission Reductions from HWP Substitution and expanded upon in Droog et al (in review). The methods also are compatible with ISO 13391 Part 3 (ISO 2025).
CCF = Hundred cubic feet
CO2e = carbon dioxide equivalent
DF = displacement factor
ISO = International Standards Organization
GWP = global warming potential
MBF = Thousand board feet
MDF = Medium Density Fiberboard
MSF = Thousand square feet
M3 = Cubic meters
MCF = Thousand cubic feet
A user has three choices for their analyses: End-use (representing wood product end-uses), Product (representing typical U.S. wood products), and Forest (representing harvested logs from US forests).
End-Use: A user can select from five broad wood product end-use categories: construction- buildings, construction- repairs, furniture, energy, packaging.
End-Use Category: Within each end-use category, a user can select from an array of sub-categories, which represent current data in the data-base. If there is not a sub-category user can select from five broad wood product
Reference Material: This is the wood material selected by the user, against which all other non-wood materials are compared. The properties of this reference material, such as its GHG emissions, carbon storage, and lifespan, are then used as inputs for the displacement factor calculation. The Reference Material is selected through a drop-down menu and only includes relevant wood material in the selected end-use subcategory.
Material Quantity: This is a number that corresponds to the unit associated with the reference material (e.g. m3). This number is used to calculate the substitution benefit.
Material types: This drop-down menu shows the different alternate material types to compare to the reference material. In some cases, there is only one alternate material type. In other cases you can choose which material to compare or select “all.”
Product: This is a wood product (e.g., softwood lumber, OSB) selected from a drop-down menu of eleven commodity wood products adapted from USFS GTR 289 (Alderman 2022). The displacement factor and substitution benefits are calculated as a weighted average of the different end-uses that the selected product goes into in the United States.
Quantity: A user enters a quantity in the units that correspond to the selected product default unit. The products and units are based on the USFS standard units for reporting U.S. wood products and are listed below:
[ Table ]
Table 1: Wood Products and their associated default units
Region: A user selects from one of four regions in the US: Pacific Coast, Inland Northwest, South, North
[ Map ]
[ Map ]
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 and then reallocated to the four regions. Much work is being done to update these values to represent a more current mix of products and distributions. 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
Material Name: This is the non-wood material the displacement factor is calculated against the reference material. Some reference materials have multiple non-wood alternatives and in this case all of them are displayed. Some of the “non-wood alternatives” can in fact include wood (e.g. redwood decking and pine decking).
Displacement Factor (kg CO2/kg CO2). The quantity of potentially avoided greenhouse gas emissions due to the displacement relative to the quantity of biogenic carbon within the wood-based product which is displacing the alternative product(s) (ISO 2025).
Estimated Potential Substitution (Kg CO2e): indicates how much GHG emissions could potentially be saved by using wood instead. This value will scale as the material quantity changes, which then shows the impact of scaling the material usage.
GWP (kg CO2 equivalent): The embodied carbon associated with manufacturing and transportation of the material. This value increases proportionally with the quantity of the material.
Kg Wood biomass (kg): The amount of biomass stored in the wood-materials (in kg). This value is constant.
Lifespan (years): The service life of the material. This value does not change with material quantity. Note: the lifespan of pallets is in trips not years.
Source: The citation (e.g., published life cycle assessment) from where the GWP, wood carbon, and lifespan information is derived.
Average Displacement Factor: If there is more than one “non-wood” alternative, a representative DF is calculated by taking the average of all the displacement factors in that category.
Product Name: The wood products the user selected from the input menu.
Quantity: The quantity of material the user input for each product (expressed in the default unit associated with the product.
Displacement Factor (unitless): The weighted average of all the average end-use DFs in which the product is used.
Upper Limit (unitless): The 90% confidence interval above the DF
Lower Limit (unitless): The 90% confidence interval below the DF
Weighted DF, Upper Limit, and Lower Limit are displayed on a graph
Estimated Potential Substitution (kg CO2e): indicates how much GHG emissions could potentially be saved from the inputted quantity of product. This value will scale as the product quantity changes.
Weighted DF: The displacement factor of all the inputted products weighted by their volume of input.
Total Estimated Substitution: The total potential GHG savings based on the quantities of inputted products.
Log Type: The log types selected from the user in the input menu
Region: The region that corresponds to the users input
Displacement Factor (unitless): The weighted average of all the downstream representative end-use DFs from which the log type is made
Upper Limit (unitless): The 90% confidence interval above the DF
Lower Limit (unitless): The 90% confidence interval below the DF
Estimated Substitution (kg CO2e): indicates how much GHG emissions could potentially be saved from the amount of harvested log. This value will scale as the product amount quantity changes.
Total Weighted DF: The displacement factor of all the inputted regions/log types weighted by their volume of input.
Total Estimated Potential Substitution (kg CO2e): The total potential GHG savings based on the quantities of user inputs.
The data used for generating estimates of displacement factors and substitution benefits are limited to US forests, products, and end-uses.
Biogenic Carbon Storage - represents the carbon stored in harvested logs or wood products.
Fossil carbon emissions- represents the fossil emissions in cradle to gate life cycle assessments.
The life cycle assessments or life cycle databases from which the GWP values are derived are cradle to grave, meaning they including A1, A2, A3, A4, A5 as well as C1-4.
The displacement factor tool was developed to provide users with broad, first-order estimates of displacement factor and potential substitution benefits. Users should understand that the results are to give users estimates of potential impacts when using more or less wood. See ISO 13391 (2025) for more information about context for users.
Data Completeness: the database contains only the wood end-uses and alternatives with which there is published credible and comparable data. This database will be continuously updated to better represent the full spectrum of wood end-uses and potential non-wood alternatives. Users are encouraged to reach out if they have published LCA information that could be included in the database.
Age of Data: The default log to product allocations and product to end-use allocations are adapted from Smith et al (2006). Efforts are underway to update both of these parameters to reflect more contemporary use trajectories of wood products.
The initial database contains five end-use categories with a current total of 101 end-uses, corresponding substitution materials and average DFs with upper 90%/lower 90% limits. The published database can be found in Droog et al (in review). This article also contains the criteria by which to include new materials by which to calculate displacement factors, which can be found below:
From Droog et al (2026): Geographic focus is the United States. Priority is given to peer-reviewed research comparing end-uses. In cases where such studies were unavailable, U.S. specific wood product EPDs were used compared to generic LCA databases such as Ecoinvent and DataSmart. When neither peer-reviewed nor EPD data specific to the U.S. were available, LCIs from published LCA studies in other regions were adjusted by using DataSmart to approximate U.S. conditions through regionally appropriate secondary data. Finally, in absence of all else, DataSmart was utilized as primary data.
The sources for each material will be displayed, color coded by the hierarchical source (Note- this is currently not built in the tool)
The product to end-use allocations used in the USDA entity-guidelines are based on data found in McKeever et al (2011) and McKeever (2009). A USFS project to update these allocations is underway but will not be complete for this phase of the platform build. In the interim, a temporary product to end-use allocation, adapted to the end-uses in this tool, was created from the following sources:
[ Table ]
Table 2: Percentage allocations of common U.S. wood products to their end-uses
[ Table ]
Table 3: Percentage break-down of three end-use categories into sub-categories.
The end-use categories are further broken into sub-end-use categories to match the data in this database. These are weighted by market share using best estimates and should be marked as highly uncertain. These parameters will be replaced when better data on market shares becomes available. Platform developers welcome any improved data with citations.
The data used to create the ratios of harvested log to primary product was adapted from Smith et al (2006) Table D6. They were reallocated from nine regions to four regions to match the regional delineations applied for the Embodied Carbon Tool. The methodology is explained in the CORRIM final report to the US Endowment (2024) and presented below::
[ Image ]
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 reports and then weighted averaged using total roundwood fractions for nonstructural products (see Table 7 from CORRIM report).
[ Table ]
Table 4: “Table 7” from CORRIM’s final report to US Endowment representing the re-allocation of nonstructural panels
[ Table ]
Table 5: Xrw percent of total roundwood (softwood/hardwood) in a region converted to a primary wood product, p
In addition, 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).
Eq DF- 1
[ Formula ]
Where:
GHGNonWood: The Global Warming Potential (GWP) of the non-wood material (in kg C). This value increases proportionally with the quantity of the material.
GHGWood: The GWP of the reference wood material (in kg C), selected by the user. This value also scales with quantity.
CarbonWtWood: The amount of biogenic carbon stored in the reference wood material (in kg). This value is constant. Note, kg C is 0.5 * kg biomass.
CarbonWtNonWood: The amount of biogenic carbon stored in the non- wood material (in kg). This value is constant.
LifespanNonWood: The lifespan of the non-wood product (in years). This value does not change with quantity.
LifespanWood: The lifespan of the reference wood material (in years). This value is also constant.
Note- This equation has been adapted from the Entity guidelines equation to adjust from functional units with different lifespans.
[ Image ]
Eq DF-2
Estimated Potential Substitution (in kg CO2e) = DF * quantity reference material
Eq DF-3
Average DF = average of all DFs in the subcategory
[ Formula ]
Eq DF- 4
Lower Limit = Group Mean – 1.645*SE
Upper Limit = Group Mean + 1.645*SE
Where:
SE = standard error, n = number elements in the sample
[ Formula ]
[ Image ]
The weighted displacement factor (DF) for each wood product is calculated by summing the result of the proportion of that product allocated to each end-use multiplied by the displacement factor associated with that end-use. This approach weights the overall displacement potential of a product according to how it is distributed across all relevant end-use markets.
Eq DF-5
DFp = Σ ( αp,e × DFe )
where the summation (Σ) is taken over all end-uses e in set E, and Σ αp,e = 1 for each product p (i.e., proportions sum to 100% across all end-uses).
Where:
αp,e = Proportion of product p allocated to end-use e (unitless; values from 0 to 1, where 1 = 100%)
DFe = Displacement factor for end-use e (kg C displaced per kg C in product)
E = Set of all end-uses considered in the analysis
Eq DF-6
DF_region_logtype = Σᵢ ( αᵢ × DFᵢ )
αᵢ — The roundwood allocation fraction for product type i. This is the proportion of incoming roundwood volume (for a given region/log-type) that is directed to product type i.
DFᵢ — The displacement factor for product type i.
i — The index variable representing each individual primary wood product type. Each term in the sum pairs one product's allocation fraction (αᵢ) with that same product's displacement factor (DFᵢ).
The expanded equation for one region_logtype (e.g. PC SW SL) is:
DF_region_logtype = (α_SWLumber × DF_SWLumber )
+ (α_HWLumber × DF_HWLumber )
+ (α_SWPlywood × DF_SWPlywood )
+ (α_HWPlywood × DF_HWPlywood )
+ (α_OSB × DF_OSB )
+ (α_Particlbd × DF_Particlbd )
+ (α_MDF × DF_MDF )
+ (α_Hardboard × DF_Hardboard )
+ (α_Fiberboard × DF_Fiberboard)
+ (α_OtherIndus × DF_OtherIndus)
+ (α_WoodPulp × DF_WoodPulp )
Where α can be found in Table 5.
[ Not sure this is needed. This would describe the output vizualizations ]
Displacement Factor- A displacement factor (DF) measures the GHG emissions savings when wood is used instead of nonwood, fossil or petroleum-based material. DFs are estimated by comparing the total GHG emission differences between wood and nonwood products and divided by the corresponding carbon content (Entity Guidelines 2024) stored in wood products.
Substitution- situation where a specific wood-based product, assembly, structure, or building is used instead of a specific alternative product, assemly, structure, or building (with functional equvalence), thus leading to avoided GHG emissions associated with the alternative product, assembly, structure or building (ISO 13301: Part 1)
Life Cycle Assessment- The compilation and evaluation of the inputs, outputs and the potential environmental impacts of a product system throughout its life cycle (ISO 14044: 2006)
GWP- index, based on radiative properties of greenhouse gases (GHG), measuring the radiative forcing following a pulse emission of a unit mass of a given GHG in the present-day atmosphere integrated over a chosen time horizon, relative to that of carbon dioxide (CO2)(ISO 14064-1:2018)
GHG- Greenhouse Gas- gaseous constituent of the atmosphere, both natural and anthropogenic, that absorbs and emits radiation at specific wavelengths within the spectrum of infrared radiation emitted by the Earth’s surface, the atmosphere and clouds [SOURCE: ISO 14050:2020, 3.9.1]
Lifespan-