Cradle-to-Gate Life-Cycle 

Assessment of Redwood Lumber 

in the United States

Kamalakanta Sahoo

Richard Bergman

United States Department of Agriculture

Forest

Service

Forest Products

Laboratory

Research Paper

FPL–RP–706

October

2020

Stephen – stock.adobe.com

Used with permission from Humboldt Sawmilll Company, LLC
October 2020

Sahoo, Kamalakanta; Bergman, Richard. 2020. Cradle-to-gate life-cycle 

assessment of redwood lumber in the United States. Research Paper 

FPL-RP-706. Madison, WI: U.S. Department of Agriculture, Forest 

Service, Forest Products Laboratory. 39 p.

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Abstract

Global demand for renewable and sustainable materials 

such as wood products is growing. To support this 

growth, a scientific approach is necessary to illustrate 

the environmental benefits of wood products. This report 

contains a detailed cradle-to-gate life-cycle assessment 

method including data collection, development of life-cycle 

inventory, and life-cycle impact assessment for production 

of redwood lumber in the United States. The results 

illustrated that redwood lumber production has a very low 

carbon footprint (37.97 kg CO2e/m3 of lumber) and stores 

about 18 times more carbon compared with its cradle-togate carbon footprint.

Keywords: Environmental impacts, wood, LCA, life-cycle 

inventory, cogeneration, product, EPD, redwood

Contents

1 Executive Summary.........................................................1

2 Introduction......................................................................3

3 Goal and Scope ................................................................4

4 Description of Industry ....................................................7

5 Description of Product .....................................................7

6 Life-Cycle Inventory Analysis.........................................8

7 Life-Cycle Impact Assessment ......................................16

8 Interpretation..................................................................19

9 Treatment of Biogenic Carbon.......................................20

10 Discussion....................................................................22

11 Completeness and Consistency Checks.......................24

12 Conclusions..................................................................25

13 Critical Review ............................................................25

14 References....................................................................25

15 Glossary of Terms........................................................27

Appendix A—Production Facility Survey 

Questionnaires....................................................................28

Appendix B—Conversion Factors and Redwood Lumber 

Product Dimensions...........................................................37
Cradle-to-Gate Life-Cycle Assessment of 

Redwood Lumber in the United States

Kamalakanta Sahoo, Post-Doctoral Researcher

Richard Bergman, Supervisory Research Forest Products Technologist

USDA Forest Service, Forest Products Laboratory, Madison, Wisconsin, USA

1 Executive Summary

1.1 Study Goals

The goal of this study was to conduct a cradle-to-gate 

life-cycle assessment (LCA) and update the environmental 

impacts associated with redwood (Sequoia sempervirens) 

lumber production in the United States (northern 

California). To develop a life-cycle inventory (LCI) and 

perform an LCA study, the authors collected primary data 

from redwood lumber production facilities per Consortium 

on Research for Renewable Industrial Materials (CORRIM) 

research guidelines. Using those LCI data, an LCA was 

produced for redwood lumber according to the Product 

Category Rule (PCR) for North American Structural and 

Architectural Wood Products. Comparative assertions were 

not the goal of this study.

1.2 Methodology

This study followed the International Organization for 

Standardization (ISO) 14040 and 14044 standards (ISO 

2006a, 2006b) to conduct an LCA study. System boundaries 

delineated the life cycle from the extraction of raw material 

inputs through product production. In this study, the 

declared unit was 1 m3 of redwood lumber (either dry or 

green and rough or planed). An industry standard production 

unit (such as MBF (thousand board feet)) was converted 

to a metric production unit (one cubic meter) of lumber. 

The authors collected primary mill data through a survey 

questionnaire emailed to redwood lumber manufacturing 

facilities followed by site visits of three major redwood 

lumber mills representing 66.6% of the total production 

volume of the redwood lumber industry in 2017. This 

survey collected all raw material inputs (including logs, fuel, 

heat, and electricity), outputs (product and coproducts), and 

pertinent emissions to water and air as well as solid waste 

generation. Secondary data, such as forestry operations and 

forest management, were from peer-reviewed literature 

per CORRIM guidelines, which included public LCA 

databases and other LCA studies. The mass and energy 

balances were calculated using primary and secondary data. 

The LCI flows and life-cycle impact assessment (LCIA) 

results were generated using LCA modeling software 

populated by the DATASMART database, which conformed 

with internationally accepted standards. The study used a 

mass-allocation approach to assign LCI and environmental 

impacts for the products and coproducts. The LCIA was 

performed using the Tool for the Reduction and Assessment 

of Chemical and Other Environmental Impacts (TRACI) 2.1 

and cumulative energy demand (CED) methods.

1.3 Life-Cycle Inventory

Cradle-to-gate LCI flows for manufacturing redwood 

lumber were presented by three life stages: (1) forestry 

operations [A1], (2) transportation of logs from forests to 

the sawmill [A2], and (3) lumber production including, 

sawing, drying, and planing [A3]. The unit process 

modeling approach was followed for conducting LCA. 

Lumber production was the most energy-intensive 

process among all followed by forestry operations and 

log transportation. Using lower heating values, the total 

cumulative primary energy consumption for cradle-to-gate 

production of redwood lumber was 1.93 GJ/m3 of lumber. 

Most energy came from renewable resources (70.17%), 

whereas a small portion of energy needs came from nuclear 

(0.84%), and the remaining 29.00% came from fossil 

resources.

1.4 Life-Cycle Impact Assessment

The following seven impact categories were examined: 

global warming (GW (kg CO2-eq)), acidification 

(kg SO2-eq), eutrophication (kg N-eq), ozone depletion 

(kg chlorofluorocarbons-11-eq), photochemical smog 

(kg NOx-eq), abiotic depletion potential for fossil resources 

(ADP fossil) (MJ), and fossil fuel depletion (MJ surplus). 

The LCI also provided additional information such as the 

use of primary energy resources consumption [energy 

consumption from nonrenewable, renewable (wind, hydro, 

solar, and geothermal), and nuclear fuels and renewable 

and nonrenewable resource consumption], water use, and 

indicators describing waste.

1.5 Key Findings

Contrary to most wood product production, emissions from 

the forest resources stage were relatively large compared 

with manufacturing emissions. The cradle-to-gate LCI 

results showed that 37.97 kg of fossil CO2 was released 

in the production of 1 m3 of redwood lumber. The carbon 

content for wood products is assumed to be 50% by mass 
Research Paper FPL–RP–706

2

of oven-dried (OD) wood (Bergman and others 2014b), 

and 1 m3 of redwood lumber stores 697 kg CO2e. Lumber 

production (Module A3) consumed more than 84% of 

total cradle-to-gate primary energy. Because of large 

renewable energy inputs including electricity and heat from 

cogeneration by mill residues, the environmental impacts of 

redwood lumber production were lower compared with the 

environmental impacts of downstream operations (Modules 

A1 and A2). Moreover, cogeneration using mill residues 

generated 294 kWh of renewable electricity/m3 of redwood 

lumber produced, from which about 76% was exported to 

the commercial grid.

About 70% of the total primary energy used in redwood 

lumber production comes from renewables, especially 

biomass (69% of total primary energy used in lumber 

production). About 48% of carbon in the logs is stored 

in lumber products, and a substantial part of the biogenic 

carbon is returned to the atmosphere by burning wood 

residues.

1.6 Sensitivity Analysis

A sensitivity analysis was completed per ISO 14040 to 

model the effects of raw material transport distance and 

consumption of energy including electricity, natural gas, 

diesel, and biomass for redwood lumber production. 

Overall, the variations in the environmental impacts 

from a 20% increase or decrease in electricity or heat or 

fuel used to produce redwood lumber were small (less 

than 10%). Similarly, a 20% increase or decrease in the 

transport distance of logs can increase or decrease the seven 

environmental impacts of redwood lumber by only 1% 

to 7%.

Table 1—Cradle-to-gate life-cycle impacts of 1 m3 of redwood lumber 

production in the United States

Impacts Units Total

Impact category

Global warming potential – TRACI 2.1 kg CO2e 37.97

Global warming potential – w/ biogenic CO2 kg CO2e 37.97

Depletion potential of the stratospheric ozone layer kg CFC11e 8.13E–07

Acidification potential of soil and water sources kg SO2e 0.35

Eutrophication potential kg Ne 0.07

Formation potential of tropospheric ozone kg O3e 10.74

Abiotic depletion potential for fossil resources (ADP fossil) MJ, NCV 511.45

Fossil fuel depletion MJ surplus 73.97

Primary energy consumption

Nonrenewable, fossil MJ 559.82

Nonrenewable, nuclear MJ 16.22

Renewable, biomass MJ 1,335.13

Renewable, wind, solar, geothermal MJ 6.94

Renewable, hydro MJ 12.65

1.7 Interpretation

The results of this study provide the cradle-to-gate 

environmental impacts of redwood lumber production 

(Table 1). The authors compared energy inputs from the 

current study (2017 data) to the earlier CORRIM study 

of 2010 data on gate-to-gate redwood lumber. About a 

43% increase in the use of primary energy was observed 

in this study compared with the previous study. Despite 

the increase in energy usage in this study compared with 

the previous study, there was a large decrease in the 

environmental impacts including GW because of the use 

of renewable resources. In this study, the energy generated 

by woody biomass constituted most of the total energy 

consumed and was more than four times higher than in the 

previous study. Similarly, the amount of energy used from 

the fossil-based source was one-half of the previous study. 

Compared with the previous study, there was a substantial 

decrease in environmental impacts of produced redwood 

lumber for major category indicators. This was caused by 

a considerable increase in the use of renewable electricity, 

especially on-site cogeneration of electricity using mill 

residues generated from the mills themselves.

1.8 Acknowledgments

We gratefully acknowledge those companies and their 

employees that participated in the surveys to obtain 

production data and those who provided financial assistance 

to the USDA Forest Service, Forest Products Laboratory, for 

this research project (19-CO-11111137-010). Any opinions, 

findings, conclusions, or recommendations expressed 

in this article do not necessarily reflect the views of the 

contributing entities.
Cradle-to-Gate Life-Cycle Assessment of Redwood Lumber in the United States

3

Abbreviations

BF board feet

CLR cubic lumber recovery

EPDs environmental product declarations

GWP global warming potential

ISO International Organization for Standardization

LCA life-cycle assessment

LCI life-cycle inventory

LCIA life-cycle impact assessment

LF lineal foot

LRF lumber recovery factor

m3 cubic meter

MBF thousand board feet

MMBF million board feet

odkg oven-dry weight wood in kilograms

PCR product category rules

tkm tonne – kilometers

2 Introduction

Globally, the use of raw materials, especially for 

construction, has increased exponentially since the 

nineteenth century (Matos 2017). Buildings and construction 

account for more than 35% of global final energy use and 

nearly 40% of energy-related CO2 emissions (Abergel and 

others 2017). The demand for construction materials is 

predicted to grow because of global population growth and 

an increased standard of living (Bringezu and others 2017). 

However, climate change and resource depletion pose a 

serious threat to human civilization. Resources from forests 

provide renewable construction materials, pulp and paper, 

energy, bioproducts, and more. Forests sequestering carbon 

and wood products storing carbon have the greatest potential 

to mitigate climate change (Canadell and Raupach 2008, 

Malmsheimer and others 2011). Combining carbon storage 

and carbon displacement by avoiding fossil-fuel-intensive 

construction materials, especially in buildings, is one of the 

most efficient options to mitigate climate change (Sathre 

and O’Connor 2010, Bergman and others 2014b, Oliver 

and others 2014). Because of environmental awareness and 

regulations, documenting the environmental performance of 

building products using LCA is becoming widespread and 

is the new accepted approach. Quantifying environmental 

performance for structural wood products is one way to 

generate green building certifications (Bergman and Taylor 

2011), provide scientific documentation [e.g., environmental 

product declarations (EPDs)], and provide information to 

stakeholders including consumers, regulating agencies, 

and policymakers. EPDs, based on the underlying LCA 

data, not only provide verified data on the environmental 

performance of products and services but can also identify 

the environmental hot spots for continuous improvements in 

a consumer-friendly format (ISO 2006a, ISO 2017).

Redwood (Sequoia sempervirens) lumber is used primarily 

for decking, fencing, and structural products in the western 

United States, and its demand has increased since the 

Great Recession in 2008 because of the growing housing 

market. Bergman and others (2013, 2014a) estimated the 

environmental impact of redwood decking (specifically 

the size 38 by 138 mm) compared with other alternative 

materials. However, with changes in the manufacturing 

process, sawmill size, and sawlog procurement distances, 

input resources especially electricity and drying 

requirements to produce redwood lumber of various 

dimensions have gone through substantial changes.

This report focuses on all redwood lumber products, 

including rough-green, rough-dry, planed-green, and planeddry lumber produced in the northern California region. 

These products fall under the United Nations Standard 

Products and Services Code (UNSPSC) of 30103601 (wood 

beams), 30103605 (wood planks), 30103607 (wood joists), 

and 30152002 (wood fencing). Redwood lumber products 

fall under the building products category of sawn timber 

(lumber). The Construction Specification Institute (CSI) 

codes (UL Environment 2018) for these products are 

06 10 00 (rough carpentry), 06 11 00 (wood framing), 

06 15 00 (wood decking), 06 16 23 (subflooring), 06 16 33 

(wood board sheathing), 06 17 43 (rim boards), 06 20 00 

(finish carpentry), 06 22 00 (millwork), 06 26 00 (board 

paneling), 06 42 13 (wood board paneling), 06 43 00 

(wood stairs and railings), 06 48 00 (wood frames), 

09 64 29 (wood strip and plank flooring), 06 22 00 

(millwork), 06 46 00 (wood trim), and 06 49 00 (wood 

screens and shutters). This report describes the energy and 

materials through a cradle-to-gate LCI on the major unit 

processes in redwood lumber manufacturing. The LCI 

data covered forest management and harvesting through to 

the final product at the sawmill gate. The environmental 

impacts GW, ozone depletion, acidification, smog, and 

eutrophication are discussed. In 2014, a similar study (but 

for planed-dry redwood decking) was performed with a 

similar goal and scope (Bergman and others 2014a).

Primary data were collected by surveying three redwood 

sawmills representing more than 66.6% of total redwood 

industry annual production (0.605 million m3

) primarily 

with a questionnaire and site visits to determine their 

material use and energy consumption for the 2017 calendar 

year (Appendix A). Peer-reviewed literature provided 

secondary data. Material balances, using data from primary 

and secondary sources, were constructed with a spreadsheet 

algorithm. The values were averaged after weighting by 

mill annual production to obtain an industry average. Inputs 

included logs, fuels, electricity, packaging materials, and 
Research Paper FPL–RP–706

4

(boiler) chemicals necessary for lumber production. Mill 

outputs included lumber and coproducts such as chips, 

sawdust, planer shavings, bark, and hog fuel. Redwood 

lumber production also consumed electricity and heat from 

cogeneration using mill residues generated during the 

lumber production process.

The data collection was performed under “CORRIM 

Guidelines for Performing Life Cycle Inventories on 

Wood Products”, undated, but current in the fall of 2012, a 

scientifically sound and consistent process established by 

CORRIM. It follows ISO 14040 standards and the PCR for 

North American Structural and Architectural Wood Products 

(UL Environment 2018, 2019). This process will guide the 

preparation of a redwood lumber EPD.

3 Goal and Scope

3.1 Goal and Objectives

3.1.1 Goals

The primary goal of this study was to generate a gate-togate LCI of redwood lumber manufacturing and link these 

data to develop a cradle-to-gate environmental profile 

of redwood lumber. The cradle-to-gate LCA followed 

data and reporting requirements as outlined in the PCR 

(UL Environment 2018) that guides the preparation of a 

business-to-business EPD.

3.1.2 Intended Audience

The primary audience for the results of this LCA report 

is redwood lumber producers in the United States, LCA 

practitioners, green building developers, and consumers.

3.1.3 Comparative Assertions

This report does not include product use (B1-B7) and endof- life (C1-C4) phases, which are required for comparative 

assertions relative to substitute products. For consistency 

with ISO 14044 guidelines and principles and compliance 

with the Wood Products PCR (UL Environment 2018, 

2019), the LCA boundary would need to be expanded to 

include the use and end-of-life phases, if future comparative 

studies are intended and disclosed to the public.

3.2 Scope of Considered System

3.2.1 Functional and Declared Unit

The purpose of the functional unit is to provide a reference 

to which all inputs and outputs are related and quantify the 

service delivered by the product system. The functional 

unit is used for EPDs covering the complete life cycle 

(i.e., cradle-to-grave) of a product. But a declared unit is 

used for EPDs that do not cover the complete life cycle 

(i.e., cradle-to-gate) of the product. In accordance with 

the PCR and ISO standards, the declared unit is one cubic 

meter (1.0 m3

) for redwood lumber (includes green-rough, 

Table 2—Types of redwood lumber 

products produced in 2017

Type of lumber product Contribution (%)

Rough-green 58.02

Partially rough-green 6.62

Partially rough-dry 5.73

Partially rough-kiln-dry 0.19

Planed-green 5.06

Planed-dry 9.29

Planed-partial-dry 14.16

Planed-air-seasoned 0.92

Total 100

dry-rough, dry-planed, etc.). The detailed product types 

are shown in Table 2 packaged for shipment at the mill 

gate. This analysis did not take the declared unit to the 

use stage; therefore, no service life was assigned. The 

cradle-to-gate LCI for redwood lumber was generated by 

examining the manufacturing data from sawmills located 

in northern California collected by survey for the year 

2017 and subsequent site visits. The datasets for upstream 

manufacturing of forestry and harvesting operations were 

collected from previously published material (Han and 

others 2015).

3.2.2 System Boundary

The cradle-to-gate system boundary is shown in Figure 1. 

The system boundary includes three information modules: 

(A1) forest management and resource harvesting; (A2) 

resource and material transportation from suppliers to the 

mill; and (A3) redwood lumber manufacturing process. The 

system boundary begins with the regeneration of the forest 

in the northern California region (A1) and ends with various 

types of redwood lumber packaged at the plant gate (A3). 

The system boundary includes forest operations, which 

may include growing seedlings in a nursery, planting the 

seedlings, managing the forest (may include precommercial 

and commercial thinning) and fertilization, and final 

harvesting with the logs brought to a forest landing. Trucks 

were used for the transportation of all resources (A2) 

including saw logs and other raw materials for lumber 

production (Fig. 1).

The sawmill complex is divided into five processes: log 

yard, sawmill, dryer, planing, and energy generation 

(optional). The study recognized five steps (A3) necessary 

to produce redwood lumber. Excluded from the system 

boundaries were fixed capital equipment and facilities, 

transportation of employees, land use, delivery of redwood 

lumber to a construction site, construction, maintenance, 

use, and final disposal. Disposal of on-site waste from 

production manufacturing was included in the system 
Cradle-to-Gate Life-Cycle Assessment of Redwood Lumber in the United States

5

Figure 1. Cradle-to-gate system boundary for redwood lumber 

production, northern California.

Table 3—System boundary inclusions and exclusions for the cradle-to-gate system of 

redwood lumber production

Included Excluded

Production of upstream processes for all resources, raw materials, 

fuels, and energy for redwood lumber production used in forestry 

operations and redwood lumber manufacturing

Fixed capital equipment and facilities

Transportation of (raw) materials throughout the cradle-to-gate 

manufacturing life stages

Transportation of employees

Packaging Construction, maintenance, use, and 

end-of-life treatments

Energy

Gasoline

Diesel

Ancillary materials

Fertilizers

Herbicides

Seedlings

Lubricants

Forest management 

and harvesting 

operations

Emissions

Air

Water

Land

Ancillary materials

Motor oils

Solvents

Antifreeze

Plastics

Energy

Diesel

Gasoline

Propane

Natural gas

Wood fuel

Electricity

A1 Resource extraction

A3 Product manufacturing

A2 Transportation

Log yard operation

O

n-s

i

t

eene

r

g

y

Produ

c

tion

s

tage

Sawmill

Drying

Planing

Packaging
Research Paper FPL–RP–706

6

boundary. Table 3 lists the inclusions and exclusions within 

the system boundaries of this study.

3.2.3 Allocation Rules

Allocation is the method used to partition the environmental 

load of a process when several products or functions share 

the same process. There are various methods of allocation 

rules and according to UL PCR, “mass” was deemed 

as the most appropriate parameter for allocation (UL 

Environment 2018). Processing of the log at the sawmill 

involved multiple unit processes with multiple outputs (i.e., 

primary products and coproducts). The mass allocation 

approach was used to partition the environmental burden 

of the manufacturing system among all outputs. When 

applying mass allocation, the environmental burden of the 

manufacturing system is “shared” between the primary 

product (e.g., redwood lumber) and the coproducts of 

production (e.g., chips, sawdust, planer shavings, etc.) based 

on their mass ratio. The sawing of logs into rough green 

lumber produced the following coproducts: bark, sawdust, 

chips, and chipper fines. The planing unit operation 

produces shavings, trim ends, and other wood waste.

3.2.4 Cut-Off Rules

The cut-off criteria for all activity stage flow considered 

within the system boundary conform with ISO 21930 

section 7.1.8 as well as UL PCR. The mass/energy of flow 

less than 1% of the cumulative mass/energy of the model 

flow was excluded, provided its environmental relevance 

was minor. The cut-off rules were not applied to hazardous 

and toxic material flows, all of which were included in the 

LCI. No material or energy input or output was knowingly 

excluded from the system boundary.

3.2.5 Data Collection

Surveys were used to collect the LCI data in accordance 

with CORRIM guidelines and ISO 14044 standards. This 

study collected production and emissions data provided 

by redwood lumber producers in northern California 

(representing more than 66% of the total annual production 

of the redwood lumber industry in 2017).

Secondary data on fuels and electrical grid inputs were 

taken from the U.S. LCI Database and European datasets 

modified specifically to be representative of U.S. operations 

(LTS 2017). Three mills provided data for 2017 redwood 

lumber and coproduct production, raw material and fuel 

use, electricity consumption, and on-site emissions. The 

primary data in the survey indicated that the majority (81%) 

of the lumber was sold as green or air-dried (Table 2). 

Data were collected from representative mills in the 

northern California region. In 2017, about 0.694 million 

m3

 of redwood lumber was produced in the United States 

or northern California. Responses from the mills through 

the survey were compared for consistency, and follow-up 

questions by mill visits, phone calls, and e-mails were used 

to clarify the responses.

3.2.6 Calculation Rules

Redwood sawmills reported logs in log scale units of 

Scribner. Based on U.S. industry measures, we used the 

conversion of 1,000 board feet (MBF) of green and dry 

wood lumber equal to 2.36 and 1.83 m3

, respectively, 

because wood shrinks as it dries from its green state to 

its final dry state and after it is planed (Bergman 2010, 

Bergman and others 2013). For this study, the conversion 

of volume from MBF to cubic meters for each dimensional 

product is presented in Table B1 in Appendix B. All flow 

analyses of the product and coproducts in the process were 

determined on an OD weight basis. Following CORRIM 

guidelines, overall wood mass balance was determined for 

material input to material output, which was within 1% 

using an average OD density (wood only) of 380 OD kg 

per m3. Whenever missing data occurred for survey items, 

they were checked with plant personnel to determine 

whether it was an unknown value or zero; if unknown, 

it was not included in the weighted average calculations. 

Missing data were carefully noted so they were not averaged 

as zero. The survey results for each unit process were 

converted to a production basis: per cubic meter of log for 

the log yard, per cubic meter of rough-green lumber for the 

sawmill, per cubic meter of rough-dry lumber for drying, 

and per cubic meter of planed-dry lumber for planing. 

The values reported by each mill were combined into a 

production weighted average for each input (Eq. 1). Thus, 

the value from a large mill had more weight. This approach 

resulted in a sawmill complex that represents a composite of 

the mills surveyed and maintained confidentiality. SimaPro, 

version 8.5.2 (Pré-Consultants 2017) was used as the 

accounting program to track all of the environmental inputs 

and outputs crossing the system boundary. Missing data 

were defined as data not reported in surveys by the redwood 

lumber facilities.

1 1

1

1 2 3 total

Y Y W1 YY Y Y 1 2 3 total

= =

1 2 3 total + + (1)

where

W1 is weighing factor for sawmill 1,

Ytotal is total annual production of “Y” mills, and

Y1 is annual production of sawmill 1.

3.2.7 Biogenic Carbon

Biobased materials such as wood contain biogenic carbon, 

and carbon accounting must follow the requirements set 

out in ISO 21930 Section 7.2.7 and 7.2.12. Per ISO 21930, 

biogenic carbon enters the product system (removal) 

as primary or secondary material. Carbon removal is 

considered a negative emission. The biogenic carbon 

leaves the system (emission) either as a product, one of the 
Cradle-to-Gate Life-Cycle Assessment of Redwood Lumber in the United States

7

coproducts, or directly to the atmosphere when combusted 

on site for energy. These mass flows of biogenic carbon 

from and to nature were listed in the LCI and expressed 

in kg CO2. In the LCIA, the LCI flow of biogenic carbon 

removal was characterized by a factor of –1 kg CO2e/

kg CO2 of biogenic carbon in the calculation of the GW 

impact category. Likewise, the LCI flow of biogenic carbon 

emission was characterized by a factor of +1 kg CO2e/kg 

CO2 of biogenic carbon in the calculation of GW. Emissions 

other than CO2 associated with biomass combustion (e.g., 

methane or nitrogen oxides) were characterized by their 

specific radiative forcing factors in the calculation of GW 

impact.

The UL PCR 2019 specifies TRACI as the default LCIA 

method for global warming potential (GWP), a 100-year 

time horizon (UL Environment 2018). The TRACI method 

does not account for the removals or emissions of biogenic 

CO2. Therefore, we manually calculated the component 

of the GW related to biogenic carbon separately. We have 

reported the GWP indicator both with and without the 

biogenic CO2 component for maximum transparency.

The results for GWP and biogenic CO2 are reported as 

follows:

• GWPTRACI: includes greenhouse gas (GHG) emissions 

from the combustion of fossil resources and GHG 

emissions other than CO2 from the combustion of 

biogenic resources (TRACI method)

• GWPBIO: adds the net emissions of biogenic carbon to the 

GW (TRACI method + net biogenic carbon)

• LCI flows of biogenic carbon emissions and removals

4 Description of Industry

The redwood lumber industry is a subset of the very broad 

forest products industry, which also produces various 

dimensions of lumber mainly for decking, furniture, fencing, 

and structural products. The redwood lumber industry is 

limited to only northern California as redwood trees only 

grow in this region of the United States.

4.1 Categories of Products and Coproducts

The main product from redwood sawmills is lumber. Other 

products (coproducts) are also made when logs, which are 

round in cross section, are processed into lumber, which 

is rectangular in cross section. These coproducts (mill 

residues) include bark, chips, sawdust, and shavings. In 

addition, logs arrive at the mill with much of the tree’s 

bark intact. The bark is removed by debarkers and used for 

fuel or sold for energy or landscaping. Another product of 

the mill is hog fuel (wood fuel), which can be strictly bark 

or a mix of bark and other coproducts depending on how 

individual mills classify it. These coproducts are either sold 

or used as fuel for on-site cogeneration and process energy 

for kiln-drying.

4.2 Annual Operating and Production 

Statistics of the Industry (U.S., Total, 

Regional)

Redwood sawmills are only located in northern California 

because of the availability of the resource. In 2017, redwood 

sawmills produced about 0.605 million m3 lumber 

(294 million board feet), which represented 100% of the 

U.S. market.

4.3  Conversion Efficiencies

The sawing (to produce rough-green lumber) had a weighted 

average lumber recovery factor (LRF) of 8.23 BF lumber/

ft3 (0.69 m3/m3) incoming log or overrun of 69%. The cubic 

recovery ratio (CRR) was 0.48 m3 lumber/m3 log. When 

the overall process was considered (to produce planed-dry 

lumber), the CRR was 0.46 m3 lumber/m3 log.

4.4 Typical Emission Control Measures by 

Plant Type

The use of pollution control devices was recorded for two 

surveyed sawmills and included devices such as baghouses 

and electrostatic precipitators.

4.5 General Types of Wastes and Emissions

The air emissions reported by most mills included dust, 

particulate matter (PM), volatile organic compounds 

(VOCs), and hazardous air pollutants (HAPs). Mills 

classed as major sources under EPA rules are required to 

report methanol, formaldehyde, phenol, acetaldehyde, 

propionaldehyde, and acrolein, which are on EPA’s HAPs 

list. If boilers are included, then there are some sulfur 

dioxide and oxides of nitrogen (NOx) emitted. There were 

emissions recorded in the surveys by two redwood sawmills.

5 Description of Product

Lumber (Fig. 2) can include a variety of products ranging 

from boards to beams and timbers. Dimensional lumber 

(nominal 2 by 6 for decking) was the main product 

(about 39% in 2017) produced at the mills in this study. 

Dimensional lumber and studs are structural products that 

consist mainly of lumber that is nominally 2 in. thick and 

4 to 12 in. wide (standard 38 mm thick by 89 to 286 mm 

wide). Redwood lumber products with various dimensions 

are shown in Table B2 in Appendix B.

5.1 Dimensions

In the United States, sizes of dimensional lumber are given 

in nominal customary units of inches. They are referred 

to as 2 by 4, 2 by 6, 2 by 8, 2 by 10, and 2 by 1. Studs are 

typically sold as 2 by 4 or 2 by 6. These numbers represent 

the nominal size of the lumber. The actual size of the lumber 
Research Paper FPL–RP–706

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can vary depending on the stage of processing. A 2 by 4 

might be 41 mm thick and 94 mm wide (1.61 in. thick by 

3.7 in. wide) when green. This condition is called “roughgreen” in this report. After drying, the actual dimensions 

might change to 39 mm thick by 90 mm wide (1.55 in. thick 

by 3.55 in. wide). This condition is called “rough-dry” in 

this report. The dimensions after final finishing (planing) are 

38 mm thick by 89 mm wide (the grading rules specify 1.5 

by 3.5 in. as the final actual size). This condition is called 

“planed-dry” in this report. The board is referred to as a 2 

by 4 at each of the three conditions even though the physical 

size changes. The planed-dry size is the same for all mills. 

The rough-green and rough-dry sizes vary among mills and 

depend on the sawing efficiency. The planed-dry thickness 

for dimensional lumber is usually 38 mm but depending 

on final use can be as much as 89 mm (up to 3.5 in). The 

widths are 89, 140, 184, 235, and 286 mm (3.5, 5.5, 7.25, 

9.25, and 11.25 in. in grading rules) for 2 by 4, 2 by 6, 2 

by 8, 2 by 10, and 2 by 12, respectively (NIST 2015). Most 

(78%) of the lumber sawn by mills in the survey was 38 mm 

thick, and 22% was in other sizes, mostly 64 by 140 mm, 

64 by 184 mm, and 89 by 89 mm (nominal 3 by 6, 3 by 8, 

and 4 by 4). The assumption was made that the processing 

inputs and emissions created when producing these sizes 

were similar to the more conventional dimensional lumber 

sizes because they were produced simultaneously at the 

same facilities. Mills specializing in thicker products might 

use different techniques; therefore, the study results should 

not be applied in those situations. Table B1 was used to 

convert the volume of lumber from MBF to cubic meters, 

which was estimated based on the information provided in 

Nielson and others (1985) and FPL (2010).

5.2 Wood Species

Redwood is a unique species growing naturally along the 

coastal area of northern California. There are three types 

of redwood: coast redwood (Sequoia sempervirens), giant 

Figure 2. Redwood lumber strapped for shipping.

sequoia (Sequoiadendron giganteum), and dawn redwood 

(Metasequoia glyptostrobides) (Save The Redwoods League 

2019). Coast redwood is the only commercial species, and it 

grows in the cool climate that makes up the coastal regions 

of northern California. In this study, the specific gravity of 

redwood considered was 0.36 and 0.38 for green and dry 

lumber, respectively.

5.3 Moisture Content

Redwood lumber products are sold as rough-green, roughdry, planed-green, and planed-dry. The average moisture 

content (MC) of the rough-green lumber was about 127% 

on a dry basis (db) produced in the sawmill. Fully kiln-dry 

lumber leaving the sawmill was about 19% MC (db). The 

MC of partially dry lumber (both rough and planed) was 

between 127% and 19% (db) depending mostly on customer 

requirements (i.e., final targeted MC).

6 Life-Cycle Inventory Analysis

The LCI in this section presents the unit process flows by 

1 m3 wood product out. The LCI was calculated based on 

2017 production and the corresponding flows of materials 

during that period. No data gaps were recorded.

6.1 A1 – Resource Extraction

Forestry extraction (operations) can include growing 

seedlings, planting, thinning, and final harvest. The 

specific processes involved are reforestation (which can 

include seedling production, site preparation, planting, 

and fertilization) and harvesting (which includes felling, 

skidding, processing, and loading for both commercial 

thinning and final harvest operations). The weighted 

average allocation to different processes considers 

inherent differences in site productivity and energy usage 

by different kinds of logging equipment. Inputs to the 

forest resources management LCI include seed, electricity 

used during greenhouse operations, fertilizer used during 

seedling production and stand growth, and the fuel and 

lubricants needed to power and maintain equipment for 

site preparation, thinning, and harvest operations. The 

primary output product for this analysis is a log destined 

for the lumber mill. The coproduct, nonmerchantable 

slash, is generally left at a landing and disposed of 

through mechanical activities or prescribed fire. For a full 

description of the redwood forestry data and LCA results, 

see Han and others (2015). In Han and others (2015), 

the collected primary data on forest management and 

harvesting operations using landowner surveys in northern 

California collectively represented 90% of redwood 

decking production. The forest operations survey developed 

representative timber harvest and raw material collection 

data including measures of all material inputs such as 

labor use and fuel and lubrication per unit of collection 

activity. Three major types of harvesting systems were 

surveyed: ground-based, skyline, and helicopter. These 

three harvesting systems were further subdivided based 
Cradle-to-Gate Life-Cycle Assessment of Redwood Lumber in the United States

9

on the equipment type used and the harvest methods 

applied (uneven-aged and even-aged). In calculating output 

variables, results were weighted by the number of acres 

in each management intensity. Weighted average harvest 

volume was forwarded to the wood product manufacturing 

modules for incorporation in their LCA.

6.2 A2 – Transport of Raw Materials from the 

Extraction Site

Delivery of logs and materials to the mills is by truck. The 

mills took possession of the logs when they were delivered 

to the log yard. The weighted average distance of log 

(roundwood) transport by logging trucks was estimated to 

be 74.6 km (one way).

6.3 A3 – Product Manufacturing

Lumber manufacturing was divided into four main unit 

processes: log yard, sawing, drying, and planing. A boiler 

provided steam for drying if needed. Figure 3 shows the 

relationship between the processes and the woody inputs 

Figure 3. Diagram of the relationship between processes used to 

create redwood lumber from logs (dotted line indicates the renewable 

electricity generated with the on-site cogeneration unit and supplied to 

unit operations in the sawmill with excess exported to the local grid).

Hog

fuel

Green

chips Bark

Sawdust

Cogeneration

Dry

chips Shavings

Sawdust

Sawing

Drying

Planing

Log yard

Logs at the

landing

Rough-green

lumber

Rough-dry

lumber

Planed-dry

lumber

Exported

electricity

to and from each process. The log yard not only served as 

a receiving area for logs, it also provided surge capacity. 

In other words, it acted as a buffer to store a large volume 

of logs so that the mill could operate if the delivery of logs 

was interrupted. The log yard included the transport of 

logs within the mill, unloading logs, grading logs, storing 

logs, and moving them to the merchandizer or debarker 

at the sawmill. The inputs to the log yard were logs on a 

truck at the harvest site and fuels, mostly diesel, used in the 

machinery to move logs within the yard. The output from 

the log yard was logs at the sawmill.

Sawing process included debarking, sawing, chipping, and 

grinding required to convert the logs to rough-green lumber 

and coproducts. The process started with debarking after 

which the logs were sawed on a head rig. The head rig 

created lumber, flitches, and cants. The flitches and cants 

passed through resaws and edgers and were cut into lumber. 

The lumber was then sorted and stacked. The bark was 

ground and either sold or used as fuel. The saws created 

sawdust, which was either sold or used as fuel. The slabs 
Research Paper FPL–RP–706

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and edgings that were not large enough to saw into lumber 

were chipped.

Drying process included the kilns, which received green 

lumber stacked on carts with wood spacers (stickers) 

between the layers. The stickers allowed air to flow between 

the layers in the dryer. Depending on customer needs, the 

stickered lumber was only air-dried (i.e., seasoned) or not 

at all. However, force-drying by dry kilns often occurred if 

only a little. The dry kilns were batch processes. In the batch 

kiln, the lumber was dried to a targeted MC typically using 

a kiln schedule. It was then moved to the dry shed or planer 

infeed. Some kilns were heated using steam generated by 

burning wood (i.e., mill residues).

Planing makes the lumber a uniform size and creates a 

smooth surface. It includes unstacking, planing, grading, 

end trimming, sorting, and packaging. Occasionally, some 

lengthwise sawing is done in the planing process. The 

process includes moving the packages and loading for 

shipment.

6.3.1 Mass Balance

The main material component used in the production of 

redwood lumber was the logs that were primarily coming 

from redwood forests managed by the sawmill or private 

owners. The average density of green logs was 360 OD 

kg/m3

 (volume green, weight OD). There were various 

types of lumber products produced when considering MC 

and surface of the lumber with primary product outputs 

of rough-green lumber, rough-dry lumber, planed-green 

lumber, planed-dry lumber, and planed-air-seasoned lumber. 

Intermediate products included rough-green lumber. 

Coproducts included bark, sawdust, pulp chips, trim ends, 

chipper fines, and planer shavings. The green, dry, and 

Table 4—Wood mass balance for redwood lumber manufacturing, 

cradle-to-gate

Input or output Units oven-dry

per m3 redwood 

lumber Percentage

Inputs

Roundwood (including bark) kg 785 100

Total inputs kg 785 100

Outputs

Primary product

 Redwood lumber kg 380 48

Coproducts

 Green chips kg 115 15

 Green sawdust kg 38 5

 Green bark kg 95 12

 Green shaving kg 55 7

 Green hog fuel kg 95 12

 Dry shavings kg 6 1

Total outputs kg 785 100

Used for on-site cogeneration kg 327 42

air-seasoned lumber had an average MC of 127%, 19%, and 

30% (db), respectively. There was also redwood lumber, 

which was partially dry at 25% MC (db). All wood fiber 

flows in the redwood lumber system were determined on an 

OD basis. To estimate the wood mass balance for redwood 

lumber production, the following technical parameters and 

assumptions were applied. The annual production of lumber 

products (surfaced-dry, surfaced-green, and rough-green) 

was reported by mills in MBF. Table B1 in Appendix B can 

be used to convert MBF to cubic meters (Nielson and others 

1985, Glass and Zelinka 2010). The average wood input 

density resulted in 360 kg/m3

 for green lumber and 

380 kg/m3 for dry lumber (Miles and Smith 2009, FPL 

2010). The average green MC for mixed wood was 

estimated to be 100% MC (db). In this study, it’s assumed 

that the MC of bark and sawdust was the same as the 

MC of the sapwood. Table 4 provides a mass balance for 

redwood lumber manufacturing for 1 m3 of redwood lumber 

product for the three-mill study sample. Of the roundwood 

(including bark) entering a sawmill, 48% of it by mass was 

processed into lumber.

6.3.2 Equipment: Type and Fuel Consumption

The equipment used in the manufacturing process falls into 

two broad categories, stationary machines and rolling stock 

(wheeled machinery, such as forklifts, for moving materials 

within a production facility). Stationary machinery in the 

sawing unit process included debarkers, circular or pony 

and head rig band saws, resaws, edgers, sorters, scanners, 

stackers, and conveyors and other handling equipment. 

Stationary equipment in the planing unit process included 

unstackers, moisture meters, planers, trim saws, sorters, 

scanners, stackers, and conveyors and other handling 

equipment. Stationary equipment was powered electrically. 
Cradle-to-Gate Life-Cycle Assessment of Redwood Lumber in the United States

11

Rolling stock, such as loaders, were used to move logs in 

the log yard unit process, to move packages of lumber from 

the one-unit process to another, and to load the final product 

for transport. Rolling stock was mainly powered by diesel 

but also to a smaller extent by gasoline and propane.

6.3.3 On-Site Heat and Power Production

The heat generated in the sawmill for lumber drying was 

either natural-gas-fired or excess heat from the cogeneration 

process where mill residues were burned in the wood 

boilers to make steam. The combustion of wood fuel and its 

emissions were included in the analysis. The unit process 

for a wood boiler was previously surveyed and reported 

in Puettmann and Milota (2017). In either case, the wood 

almost always came from mill residues produced on site. 

A weighted average of 24% of total electricity cogenerated 

on site was consumed in the sawmill, and 76% was sold 

to the local grid. Some of the exhaust steam from the 

cogeneration (combined heat and power) plant was used in 

the wood drying process. Only 11% of the heat produced 

in the cogeneration was needed for lumber drying, and 

the rest was waste heat, which decreased the overall 

efficiency of this aspect of the manufacturing operation. 

All exhaust steam was condensed and then returned to the 

wood boiler for further use. The environmental burdens 

from the cogeneration were allocated to the electricity 

produced and part of the heat consumed during the lumber 

drying operation. Waste heat from the cogeneration unit did 

not carry any of the impacts. In summary, the electricity 

and usable heat carried 88% and 12% of total impacts, 

respectively, and this allocation was based on the energy 

content of products and efficiency of prime mover, which 

converted steam to electricity. It was estimated that 1.11 kg 

of OD wood residues produced 1 kWh of electricity and 

2.49 MJ of useful heat (excluding waste heat) to be used in 

the kiln for lumber drying. Most redwood lumber products 

are sold as green, and hence the requirement of the heat was 

minimal. The boilers used 100% self-generated fuel, and 

excess wood fuel was sold. The fuel supplied to the wood 

boilers was 28.4% green chips, 9.3% sawdust, 23.4% green 

bark, 15.6% planer shavings, and 23.4% hog fuel (Table 5).

6.3.4 Log Yard Operations

The log yard unit process begins with logs plus the attached 

bark on a truck at the harvest site and ends with logs plus 

the attached bark delivered to the infeed sawing process 

(i.e., debarker). Logging trucks arrive at the log yard and 

are unloaded by diesel-powered wheeled loaders with log 

grapples (also referred to as on-site loaders and haulers or 

rolling stock). The unloading machines are a part of the log 

yard unit process.

The log truck might be weighed in and out; however, all 

mills reported log input on a volume basis, either board feet 

or cubic feet. When the log trucks are unloaded, the logs are 

either piled in a storage deck or they are spread out, graded 

visually, and then transferred to the log deck. The logs are 

stored in decks for months to years. Having an inventory 

in the decks allows the mill to keep running even when log 

deliveries are temporarily interrupted because of weather, 

fire, or other supply issues. Generally, water is sprayed 

on the logs piles to keep them wet to maintain freshness 

and prevent stain and cracking. The logs are then removed 

from the deck and taken to the debarker at the infeed of 

the sawmill. Logs entering are reported on a volume basis, 

eastside Scribner. Log scale is a century-old method of 

measuring logs in which measurements of diameter and 

length are used to predict the board feet of lumber to be 

recovered from the log. Because of technology changes 

and changes in average log diameter, log scale greatly 

underestimates the board feet currently recovered. The log 

scale quantities reported were converted to cubic volume 

using a factor of 5.81 m3

/MBF. Diesel and gasoline were 

used as fuel for rolling stock (wheeled machinery, such as 

loaders, forklifts, and lumber carriers) for log unloading 

and moving logs through the process. Lube oil, hydraulic 

oil, grease, and antifreeze were also used in rolling stock. 

Lubricants and solvents for cleaning are also used in 

stationary equipment. A small amount of electricity is used 

in the log yard for lighting and instrumentation (Table 6).

6.3.5 Sawmill Operations – Production of Rough 

Green Lumber

The sawing process begins when logs with bark are received 

from the log yard and ends when rough sawn green lumber 

is stacked on stickers and packaged for sale or transported 

to the drying process. Additionally, chips, sawdust, bark, 

and hog fuel are created in the sawing process, all in green 

condition. Table 7 shows the products from and inputs to 

this process. Coproduct masses are listed in bone dry. The 

allocation was based on bone-dry mass. Bone-dry and OD 

terms are used interchangeably.

A combination of decks and conveyors move the logs 

and lumber through the system. Logs are first debarked. 

Dimensional lumber mills often have a scanning system to 

optimize bucking to match the log characteristics, whereas 

stud mills, with a more restricted product line, buck to 

stud lengths. The logs are then scanned before sawing so 

that the location of the saw cuts made by the headrig will 

maximize the value of the product from the log. A variety of 

lumber sizes are produced by the headrig. Additional sawing 

machine centers include resaws and edgers. Most mills have 

a curved resaw (curve saw) so that logs with mild sweep can 

be sawn more efficiently. These additional machine centers 

create lumber that will meet the grading rules. Additional 

scanning occurs at the machine centers to optimize recovery. 

Pieces may pass through more than one saw.

After sawing, the lumber usually flows from all machine 

centers to a single sorting line. Here the pieces are graded, 

scanned, and trimmed to length. The length trim is done if 
Research Paper FPL–RP–706

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Table 5—Inputs to wood boiler per bone dry kilogram of wood fuel combusteda

Description Value Unit Allocation (%)

Product

Cogeneration electricity, at sawmill, kWh, U.S. 1 kWh 88

Cogeneration heat, at sawmill, for drying, MJ, U.S. 2.49 MJ 12

Wood ash, at boiler, at mill, kg, U.S. v1.2 0.0212 kg

Resource

Water, process, surface 0.34 kg

Water, process, well 0.27 kg

Water, process, surface 0.88 kg

Water, process, well 0.27 kg

Material/fuel

Chips, redwood, green, kg, C-U.S. 0.3151 kg

Sawdust, redwood, green, kg, C-U.S. 0.1029 kg

Hog fuel, redwood, green, kg, C-U.S. 0.2596 kg

Bark, green, kg, C-U.S. 0.2593 kg

Shavings, dry, kg, C-U.S. 0.1732 kg

Diesel, loaders and haulers 0.0219 L

Gasoline, loaders and haulers 8.94E–04 L

Propane, loaders and haulers 4.38E–05 L

Engine oil, in engines of loaders and haulers 1.34E–05 kg

Engine oil, stationary equipment 5.55E–06 kg

Hydraulic fluid for loaders and haulers 2.11E–05 kg

Hydraulic oil for stationary equipment 7.77E–06 kg

Transmission fluid, loaders and haulers 5.00E–05 kg

Ethylene glycol, at plant 4.44E–07 kg

Solvent, at plant/U.S. 1.19E–06 kg

Solvent, at plant/U.S. 5.55E–08 kg

Water treatment, at plant/U.S. 7.44E–07 kg

Boiler streamline treatment 1.37E–04 kg

Oils, mobile equipment 4.07E–06 kg

Oils, stationary equipment 2.22E–06 L

Urea, as N, at regional storehouse 1.11E–05 kg

Disposal, ash, to unspecified landfill 3.50E–03 kg

Disposal, solid waste, unspecified, to unspecified landfill, RNA 8.42E–03 kg

Metal, to recycling, RNA 8.06E–06 kg

Electricity/heat

Electricity, at grid, U.S. 9.10E–02 kWh

Natural gas, combusted in industrial boiler/U.S. 1.53E–03 m3

Emissions to air

Acetaldehyde 1.17E–06 kg

Acrolein 8.96E–07 kg

Benzene 1.88E–07 kg

Carbon monoxide, biogenic 3.59E–03 kg

Carbon dioxide, biogenic 1.95E+00 kg

Wood (dust) 6.24E–04 kg

Formaldehyde 1.40E–05 kg

HAPs, hazardous air pollutants 6.96E–06 kg

Hydrogen chloride 1.30E–06 kg

Lead 1.94E–07 kg

Mercury 2.03E–09 kg

Methane, biogenic 2.48E–05 kg

Methanol 8.82E–06 kg

Nitrogen oxides 1.22E–03 kg
Cradle-to-Gate Life-Cycle Assessment of Redwood Lumber in the United States

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Table 5—Inputs to wood boiler per bone dry kilogram of wood fuel combusteda—con.

Description Value Unit Allocation (%)

Emissions to air—con. 1.22E–03 kg

Particulates, <10 μm 5.23E–04 kg

Particulates, <2.5 μm 1.54E–04 kg

Phenol 6.89E–07 kg

Propanol 5.71E–08 kg

Sulfur dioxide 8.56E–05 kg

VOC, volatile organic compounds 9.72E–04 kg

Dinitrogen monoxide (nitrous oxide) 3.25E–06 kg

Naphthalene 6.40E–08 kg

Other organic 2.34E–07 kg

Emissions to water

Suspended solids, unspecified 9.27E–07 kg

BOD5, biological oxygen demand 2.33E–06 kg a

3.6 MJ = 1 kWh.

Table 6—Inputs and outputs for the log yard process. Values are per cubic meter of redwood 

logs leaving log yard and delivered to the sawmill for northern California, USA

Description Value Unit Allocation (%)

Product

Roundwood sawlogs, redwood, green, at sawmill, m3

, CA-U.S. 1 m3 100

Resource

Water, process, unspecified natural origin/kg 22.46 L

Material/fuel

Roundwood sawlogs, redwood, green, at log yard m3

, CA-U.S. 1 m3

Diesel, combusted in industrial equipment NREL/U.S. U 5.65E–01 L

Gasoline, combusted in equipment NREL/U.S. U 1.74E–03 L

Lubricating oil, at plant/U.S.- U.S.-EI U (a proxy for hydraulic fluid) 1.24E–02 kg

Lubricating oil, at plant/U.S.- U.S.-EI U (a proxy for motor oil) 2.12E–02 kg

Lubricating oil, at plant/U.S.- U.S.-EI U (a proxy for oil and grease) 4.42E–04 kg

Electricity/heat

Cogeneration renewable electricity 0.50 kWh

Electricity, low voltage WECC, U.S. only | market for | cut-off, U 0.15 kWh

Emissions to water

COD, chemical oxygen demand 1.07E–05 kg

Oils, unspecified 7.69E–06 kg

Zinc 1.20E–04 kg
Research Paper FPL–RP–706

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Table 7—Unit process inputs and outputs for sawing to produce 1 m3 of rough-green redwood 

lumber for northern California, USA

Description Value Unit Allocation (%)

Product

Sawn lumber, redwood, rough, green, m3

, CA-U.S. 1 m3 49

Bark, redwood, green, kg, CA-U.S. 107.53 kg 15

Chips, redwood, green, kg, CA-U.S. 35.12 kg 5

Sawdust, redwood, green, kg, CA-U.S. 88.50 kg 12

Shavings, redwood, green, kg, CA-U.S. 51.61 kg 7

Hogged fuel, redwood, green, kg, CA-U.S. 88.58 kg 12

Material/fuel

Roundwood sawlogs, redwood, green, at sawmill, m3

, CA-U.S. 2.03 m3

Diesel, combusted in industrial equipment NREL/U.S. U 0.20 L

Gasoline, combusted in equipment NREL/U.S. U 0.03 L

Lubricating oil, at plant/U.S.- U.S.-EI U (a proxy for hydraulic fluid) 6.98E–02 kg

Lubricating oil, at plant/U.S.- U.S.-EI U (a proxy for motor oil) 3.25E–02 kg

Polyethylene, HDPE, granulate, at plant/U.S.- U.S.-EI U (a proxy for plastics) 8.57E–03 kg

Alkyd paint, white, 60% in H2O, at plant/RER with U.S. electricity U 8.31E–04 kg

Tap water, at user/RER with U.S. electricity U 4.22E–01 kg

Surfaced-dried lumber, at planer mill, CA-U.S./kg/U.S. - stickers 8.12E–01 kg

Electricity/heat

Cogeneration renewable electricity 19.32 kWh

Electricity, low voltage WECC, U.S. only | market for | cut-off, U 5.66 kWh

Emissions to water

COD, chemical oxygen demand 4.91E–05 L

Oils, unspecified 5.08E–07 L

the end of a piece has a grade-limiting defect and its value 

can be raised by trimming. The pieces are then sorted for 

length and width. Finally, the lumber is stacked on stickers 

(spacers) in units that are removed from the sawmill by 

a diesel-powered forklift. Redwood lumber is used as 

rough-green, partially rough-green, partially rough-dry, 

planed-green, planed-dry, planed-partial-dry, and planedair-seasoned. The rough-green lumber stacks are stored 

outdoors for air-drying to decrease the MC of lumber (e.g., 

nearly 35% MC db) before sending, if needed, to the kiln- 

(force) drying operation. A large portion of rough-green 

lumber stacks are packed for customer delivery.

Lumber was reported in board feet for each lumber size. 

Board feet reported values were then converted to cubic 

meters as described in section 4.1 of this report using the 

actual lumber dimensions reported by each mill. All mills 

reported actual dimensions (target size) for each roughgreen lumber size. One cubic meter of redwood lumber 

was produced from 2.03 m3

 of logs. Products were more 

accurately measured than logs, and lumber made up 49% 

of the wood leaving the sawmill. The balance of the wood 

leaving (51%) was chips, sawdust, bark, wood fuel, and 

hog fuel (Table 7). These coproducts were used for on-site 

cogeneration (~42% of incoming logs) and were sold to be 

used as mulch (9%).

Diesel, gasoline, and liquefied petroleum gas were used as 

fuel for rolling stock for moving lumber from the process. 

Lube oil, hydraulic oil, grease, and antifreeze were also used 

in rolling stock. Lubricants and solvents for cleaning were 

also used in stationary equipment. Some plastic and metal 

strapping were used. Electricity was used in the sawmill to 

operate motors, instrumentation, and lighting (Table 7).

6.3.6 Drying Operations – Production of 

Rough-Dry Lumber

Redwood sawmills adopt either air-drying or kiln-drying 

or a combination of both depending on the target MC 

required by the customers. Air-drying is slow and may 

require a long time to dry. Sometimes target MC cannot 

be achieved because of local weather conditions. The 

sawmill’s inventory of a specific product, local climate, and 

weather conditions also dictate the type of lumber drying 

arrangements. The kiln-drying process begins with rough 

sawn green or partially air-dry lumber placed at the kiln 

and ends with rough-dry lumber either delivered to the 

planer or sold as rough-dry lumber. There is approximately 

7% volume loss caused by shrinkage and a corresponding 

increase in specific gravity.

Dry kilns are chambers 16 to 40 m long, usually with a left 

side and a right side. There is a set of tracks on each side 
Cradle-to-Gate Life-Cycle Assessment of Redwood Lumber in the United States

15

so lumber can be rolled through the kiln on carts. Each 

side holds a track of lumber approximately 2.4 to 3 m (two 

units) wide and 4 to 5 m (two to three units) high. For 

the surveyed sawmills, the exhaust steam generated from 

either the cogeneration plant or natural gas-fired boilers 

was used to supply heat for the kiln-drying process. There 

are fans that circulate air through the sticker slots between 

the layers of lumber. Steam heat exchangers (heating 

coils) provide the energy to heat the air to the desired 

temperature. The humidity is controlled by ventilators that 

open to release moist warm air and take in ambient air. 

The humidity can be raised by releasing live steam into 

the chamber. The temperature and humidity in the kilns 

are controlled to a drying schedule, a series of dry-bulb 

and wet-bulb temperatures designed to remove moisture as 

quickly as possible without damaging the wood (Simpson 

1991, Bergman 2010). For redwood, the maximum drying 

temperature ranged from about 80 to 100 °C. A portion of 

the rough-dry lumber (graded, trimmed, sorted, stacked, 

and packed using plastic straps) was sold to the customers, 

whereas the rest went to the planing process.

Nonwood materials were tracked too. Almost all water 

used for the facility was allocated to the log yard and 

cogeneration plant; a very small amount was used in the 

sawing and planing operations. Diesel, gasoline, and 

liquefied petroleum gas were used as fuel for forklifts and 

modified front end loaders, which were used for moving 

lumber into the kiln, out of the kiln, and to the planer. Lube 

Table 8—Unit process inputs and outputs for drying 1 m3 of rough-dry redwood lumber 

(values are per cubic meter of rough-dry redwood lumber for northern California, USA)

Description Value Unit Allocation (%)

Product

Sawn lumber, redwood, rough, dry, m3

, CA-U.S. 1 m3 100

Material/fuel

Sawn lumber, redwood, rough, green, m3

, CA-U.S. 1.07 m3

Diesel, combusted in industrial equipment NREL/U.S. U 0.09

Gasoline, combusted in equipment NREL/U.S. U 0.02 L

Lubricating oil, at plant/U.S.- U.S.-EI U (a proxy for hydraulic fluid) 5.62E–03 kg

Lubricating oil, at plant/U.S.- U.S.-EI U (a proxy for motor oil) 9.25E–03 kg

Tap water, at user/RER with U.S. electricity U 4.45E–01 kg

Electricity/heat

Cogeneration renewable electricity 2.72 kWh

Electricity, low voltage WECC, U.S. only | market for | cut-off, U 0.80 kWh

Heat, on-site boiler (natural gas fired) 94.72 MJ

Exhaust heat from cogeneration boiler 733.19 MJ

Emissions to water

COD, chemical oxygen demand 0.00E+00 kg

Oils, unspecified 8.85E+01 kg

Emissions to air

Particulates, nonboiler 1.13E–05 kg

VOC, volatile organic compounds 3.05E–02 kg

oil, hydraulic oil, grease, and antifreeze were used in rolling 

stock. Lubricants and solvents for cleaning were also used 

in stationary equipment. Electricity, 3.52 kWh/m3 (Table 8) 

sourced from cogen and grid, was used in the dryer to 

operate motors, instrumentation, and lighting. The kiln 

emissions were created when the wood was dried.

6.3.7 Planing Operations – Production of 

Packaged Planed-Dry Lumber

The planing process begins with units of rough-green or 

rough-dry or partially rough-dry lumber placed at the infeed 

and ends with packaged planed or partially planed lumber 

loaded for shipment (Table 9). Additionally, planer shavings 

are created in the planing process. Redwood lumber is 

planed relatively lightly as indicated by the small amount of 

planar shavings generated (6.47 OD kg/m3

) compared with 

that of other lumber products (Bergman and Bowe 2008, 

2010, 2012; Puettmann and others 2010). The planed lumber 

is graded, trimmed, sorted, and stacked before packaging.

The product is packaged in units that are composed of 

lumber of a single thickness, width, and (usually) length. 

Lath is placed between some layers in the unit to prevent the 

side pieces from falling when the consumer opens the unit. 

The units are usually covered with a paper wrap. End paint 

might be applied, and the unit might be stenciled. The units 

are banded with plastic strapping. Runners are placed under 

the units to allow access for the forklift tines. The packaged 

units are then placed on trucks for transport.
Research Paper FPL–RP–706

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Table 9—Unit process inputs and outputs for producing 1 m3 of planed-dry redwood lumber for 

northern California, USA

Description Value Unit Allocation (%)

Product

Sawn lumber, redwood, plane, dry, m3

, CA-U.S. 1 m3 98.33

Planer shavings, dry, kg, CA-U.S. 6.47 kg 1.67

Material/fuel

Sawn lumber, redwood, rough, dry, m3

, CA-U.S. 1.02 m3

Diesel, combusted in industrial equipment NREL/U.S. U 0.09 L

Gasoline, combusted in equipment NREL/U.S. U 0.02 L

Natural gas, combusted in industrial equipment NREL/RNA U 0.01 L

Lubricating oil, at plant/U.S.- U.S.-EI U (a proxy for hydraulic fluid) 2.09E–02 kg

Lubricating oil, at plant/U.S.- U.S.-EI U (a proxy for motor oil) 2.39E–02 kg

Polyethylene, HDPE, granulate, at plant/U.S.- U.S.-EI U (a proxy for plastics) 4.70E–02

Tap water, at user/RER with U.S. electricity U 4.53E–01 kg

Electricity/heat

Cogeneration renewable electricity 10.28 kWh

Electricity, low voltage WECC, U.S. only | market for | cut-off, U 3.01 kWh

Emissions to water

Suspended solids, unspecified 1.13E–06 kg

COD, chemical oxygen demand 1.57E–05 kg

The planer used water for cooling machinery and dust 

control. Diesel, gasoline, and liquefied petroleum gas were 

used as fuel for rolling stock for moving lumber from the 

process to truck, rail, or ships. Lube oil, hydraulic oil, 

grease, and antifreeze were used in rolling stock. Lubricants 

and solvents for cleaning were also used in stationary 

equipment. Electricity, 13.29 kWh/m3, was used in the 

planer to operate motors, instrumentation, and lighting.

6.4 Secondary Data Sources

Table 10 lists the secondary LCI data sources used in this 

LCA study for raw material inputs, ancillary materials and 

packaging, transportation of materials and resources, fuels 

and energy for manufacturing, water sources, and waste 

streams.

7 Life-Cycle Impact Assessment

The LCIA phase establishes links between the LCI results 

and potential environmental impacts. The LCIA calculates 

several impact indicators including GW, eutrophication, 

and smog. These impact indicators provide general, but 

quantifiable, indications of potential environmental impacts. 

The target impact indicator, the impact category, and means 

of characterizing the impacts are subsequently summarized. 

Environmental impacts are determined using the TRACI 

method (Bare 2011). Each impact indicator is a measure of 

an aspect of a potential impact. This LCIA does not make 

value judgments about the impact indicators, meaning 

comparison indicator values are not valid. Additionally, 

each impact indicator value is stated in units that are not 

comparable with others. For the same reasons, indicators 

should not be combined or added. Additionally, the LCIA 

results are relative expressions and do not predict impacts 

on category endpoints, the exceeding of thresholds, safety 

margins, or risks. The primary fuels are categorized into 

nonrenewable (fossil and nuclear) and renewable (biomass, 

geothermal, solar, wind, hydro). Table 11 summarizes the 

source and scope of each impact category reported in this 

report, which is required to be in conformance with the 

PCR.

Cradle-to-gate environmental performance results for all 

reporting indicators are listed in Table 12 for redwood 

lumber. The LCIA results in Table 12 show the absolute 

values for A1-resource extraction, A2-transportation, and 

A3-redwood lumber production. About 41% of the CO2

equivalent emissions (GWP) came from producing lumber 

(15.75 kg CO2 eq), with 40% assigned to forestry operations 

(15.16 kg CO2 eq). Transportation, which is primarily the 

transport of logs to the sawmill, was 7.06 kg CO2 eq or 19% 

of the cradle-to-gate GWP impact.

Table 12 also provides indicators related to energy use, 

material resource consumption, and renewable secondary 

fuels (RSF) generated. The total cradle-to-gate energy use 

was 1,931 MJ/m3. This value is 43% higher than that in the 

previous study (Bergman and others 2014a), which reported 

a value of 1,340 MJ/m3

 for planed-dry redwood decking. 

The total cradle-to-gate renewable and nonrenewable 

energies are 1,335 and 609.2 MJ, respectively. Most of the 

freshwater use is in the A3 life-cycle stage. Freshwater use 

was recorded for log sprays and cogeneration boiler use 

(195.5 L/m3

).
Cradle-to-Gate Life-Cycle Assessment of Redwood Lumber in the United States

17

Table 10—Secondary data sources (LTS 2017) and data quality assessment

LCI data source Geography Year Data quality assessment

A1: Raw material inputs

Inputs

Wood resource Database: CORRIM dataset

Process: Roundwood, 

redwood, average, at forest 

road, CA-U.S

North America – 

region specific

2005–2019 Technology: Good. Process models region-specific 

technology.

Time: Good. Some data are less than 10 years old.

Geography: Very good. Data are representative of 

regional production.

A2: Raw material transportation

Inputs

Trucking Database: US EI 2.2 

(DataSmart, LTS 2017)

Process: Transport, 

combination truck, dieselpowered NREL/U.S. U

North America 2018 Technology: Very good. Process models average 

North American technology.

Time: Good. Data are less than 10 years old.

Geography: Very good. Data are representative of 

North American trucking.

A3: Manufacturing

Energy inputs

Electricity Database: US EI 2.2 

(DataSmart, LTS 2017)

North America – 

region specific

2018 Technology: Very good. Process models average 

electricity technology specific to regional grids.

Time: Very good. Data are less than 5 years old.

Geography: Very good. Data are representative of 

regional electricity generation.

Gasoline Database: US EI 2.2 

(DataSmart, LTS 2017)

Process: Gasoline, 

combusted in equipment 

NREL/US U

North America 2018 Technology: Very good. Process models average 

North American technology.

Time: Very good. Data are less than 5 years old.

Geography: Very good. Data are representative 

of North American propane production and 

combustion.

Diesel Database: US EI 2.2 

(DataSmart, LTS 2017)

Process: Diesel, combusted 

in industrial equipment 

NREL/US U

North America 2018 Technology: Very good. Process models average 

North American technology.

Time: Very good. Data are less than 5 years old.

Geography: Very good. Data are representative of 

North American diesel production and combustion.

Biomass 

combustion

Database: CORRIM data

Process: Wood combusted, 

at boiler, at mill, kg, US

North America 2015 Technology: Very good. Process represents 

combustion of biomass in an industrial boiler.

Time: Very good. Data are within two years.

Geography: Very good. Data are representative of 

North American biomass combustion.

Ancillary 

materials and 

packaging

Hydraulic fluid 

and lubricants

Database: US EI 2.2 

(DataSmart, LTS 2017)

Process: Lubricating oil, at 

plant/US- US-EI U

North America 2018 Technology: Very good. Process models average 

North American technology.

Time: Very good. Data are less than 5 years old.

Geography: Very good. Data are representative of 

North American processes.

Antifreeze Database: US EI 2.2 

(DataSmart, LTS 2017)

Process: Ethylene glycol, at 

plant/US - US-EI U

North America 2018 Technology: Very good. Process models average 

North American technology.

Time: Very good. Data are less than 5 years old.

Geography: Very good. Data are representative of 

North American processes.

Solvents Database: US EI 2.2 

(DataSmart, LTS 2017)

Process: Hexane, at plant/

US- US-EI U

North America 2018 Technology: Very good. Process models average 

North American technology.

Time: Very good. Data are less than 5 years old.

Geography: Very good. Data are representative of 

North American production and combustion.

Plastic strap Database: US EI 2.2 

(DataSmart, LTS 2017)

Process: Polyethylene, 

HDPE, granulate, at plant/

US- US-EI U

North America 2018 Technology: Very good. Process models average 

North American technology.

Time: Very good. Data are less than 5 years old.

Geography: Very good. Data are representative of 

North American processes.

Greases and oils Database: US EI 2.2 

(DataSmart, LTS 2017)

Process: Lubricating oil, at 

plant/US- US-EI U

North America 2018 Technology: Very good. Process models average 

North American technology.

Time: Very good. Data are less than 5 years old.

Geography: Very good. Data are representative of 

North American processes.
Research Paper FPL–RP–706

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Table 11—Selected impact indicators, characterization models, and impact categories

Reporting category per tables E1–E5 in ISO 21930 Indicator name Abbreviation Unit

Core mandatory impact indicators Global warming potential, fossil GWPTRACI kg CO2e

Core mandatory impact indicators Global warming potential, w/ biogenica GWPBIO kg CO2e

Core mandatory impact indicators Depletion potential of the stratospheric ozone 

layer

ODP kg CFC11e

Core mandatory impact indicators Acidification potential of soil and water sources AP kg SO2e

Core mandatory impact indicators Eutrophication potential EP kg PO4e

Core mandatory impact indicators Formation potential of tropospheric ozone SFP kg O3e

Core mandatory impact indicators Abiotic depletion potential for fossil resources 

(ADP fossil)

ADPf MJ, NCV

Core mandatory impact indicators Fossil fuel depletion FFD MJ 

surplus

Use of primary resources Renewable primary energy carrier used as 

energy

RPRE MJ, NCV

Use of primary resources Renewable primary energy carrier used as 

material

RPRM MJ, NCV

Use of primary resources Nonrenewable primary energy carrier used as 

energy

NRPRE MJ, NCV

Use of primary resources Renewable primary energy carrier used as 

material

NRPRM MJ, NCV

Secondary material, secondary fuel and recovered energy Secondary material SM kg

Secondary material, secondary fuel and recovered energy Renewable secondary fuel RSF MJ, NCV

Secondary material, secondary fuel and recovered energy Nonrenewable secondary fuel NRSF MJ, NCV

Secondary material, secondary fuel and recovered energy Recovered energy RE MJ, NCV

Mandatory inventory parameters Consumption of freshwater resources; FW m3

Indicators describing waste Hazardous waste disposed HWD kg

Indicators describing waste Nonhazardous waste disposed NHWD kg

Indicators describing waste High-level radioactive waste, conditioned, to 

final repository

HLRW kg or m3

Indicators describing waste Intermediate- and low-level radioactive waste, 

conditioned, to final repository

ILLRW kg or m3

Indicators describing waste Components for re-use CRU kg

Indicators describing waste Materials for recycling MR kg

Indicators describing waste Materials for energy recovery MER kg

Indicators describing waste Recovered energy exported from the product 

system

EE MJ, NCV

Additional inventory parameters for transparency Biogenic carbon removal from product BCRP kg CO2e

Additional inventory parameters for transparency Biogenic carbon emission from product BCEP kg CO2e

Additional inventory parameters for transparency Biogenic carbon removal from packaging BCRK kg CO2e

Additional inventory parameters for transparency Biogenic carbon emission from packaging BCEK kg CO2e

Additional inventory parameters for transparency Biogenic carbon emission from combustion 

of waste from renewable sources used in 

production processes

BCEW kg CO2e

Additional inventory parameters for transparency Carbon emissions from combustion of waste 

from nonrenewable sources used in production 

processes

CWNR kg CO2e

a

ISO 21930 requires a demonstration of forest sustainability to characterize carbon removals with a factor of –1 kg CO2e/kg CO2. ISO 21930 Section 7.2.1 

Note 2 states the following regarding demonstrating forest sustainability: “Other evidence such as national reporting under the United Nations Framework 

Convention on Climate Change (UNFCCC) can be used to identify forests with stable or increasing forest carbon stocks.” Canada’s UNFCCC annual report 

table 6-1 provides annual NET GHG Flux Estimates for different land use categories. This reporting indicates nondecreasing forest carbon stocks and thus 

the source forests meet the conditions for characterization of removals with a factor of –1 kg CO2e/kg CO2.
Cradle-to-Gate Life-Cycle Assessment of Redwood Lumber in the United States

19

Table 12—Cradle-to-gate environmental performance of 1 m3 redwood lumber based on mass allocation for 

northern California, USA

Reporting category and indicator name Abbreviation Unit Total A1 A2 A3

Core mandatory impact indicator

Global warming potential – TRACI 2.1 GWPTRACI kg CO2e 37.97 15.16 7.06 15.75

Global warming potential – w/ biogenic CO2 GWPBIO kg CO2e 37.97 –1,424.19 7.06 1,455.10

Depletion potential of the stratospheric ozone layer ODP kg CFC11e 8.13E–07 6.11E–09 2.69E–10 8.07E–07

Acidification potential of soil and water sources AP kg SO2e 0.35 0.20 0.04 0.11

Eutrophication potential EP kg Ne 0.07 0.01 0 0.06

Formation potential of tropospheric ozone SFP kg O3e 10.74 6.28 1.15 3.31

Abiotic depletion potential for fossil resources 

(ADP fossil)

ADPf MJ, NCV 511.45 205.42 88.02 218.01

Fossil fuel depletion FFD MJ surplus 73.97 31.48 13.50 28.99

Use of primary resources

Renewable primary energy carrier used as energy RPRE MJ, NCV 1,354.71 0.23 0 1,354.49

Renewable primary energy carrier used as material RPRM MJ, NCV 7,942.00 0 0 7,942.00

Nonrenewable primary energy carrier used as energy NRPRE MJ, NCV 576.04 218.26 93.50 264.28

Nonrenewable primary energy carrier used as material NRPRM MJ, NCV 0 0 0 0

Secondary material, secondary fuel and recovered energy

Secondary material SM kg 0 0 0 0

Renewable secondary fuel RSF MJ, NCV 0 0 0 0

Nonrenewable secondary fuel NRSF MJ, NCV 0 0 0 0

Recovered energy RE MJ, NCV 0 0 0 0

Mandatory inventory parameters

Consumption of freshwater resources FW m3 0.159 0.00 0.00 0.159

Indicators describing waste

Hazardous waste disposed HWD kg 0 0 0 0

Nonhazardous waste disposed NHWD kg 9.63 0.00 0.00 9.63

High-level radioactive waste, conditioned, to final 

repository

HLRW m3 1.43E–07 1.01E–10 0 1.43E–07

Intermediate- and low-level radioactive waste, 

conditioned, to final repository

ILLRW m3 3.71E–08 2.10E–11 0 3.70E–08

Components for re-use CRU kg 0 0 0 0

Materials for recycling MR kg 0.057 0 0 0.057

Materials for energy recovery MER kg 0 0 0 0

Recovered energy exported from the product system EE MJ, NCV 0.000 0 0 0.000

8 Interpretation

As defined by ISO, the term life-cycle interpretation is 

the phase of the LCA in which the findings of either the 

LCI or the LCIA, or both, are combined consistently 

with the defined goal and scope to reach conclusions 

and recommendations. This phase in the LCA reports the 

significant issues based on the results presented in the LCI 

and LCIA of this report. Additional components report 

an evaluation that considers completeness, sensitivity, 

and consistency checks of the LCI and LCIA results, 

conclusions, limitations, and recommendations.

8.1  Identification of the Significant Issues

The objective of this element is to structure the results from 

the LCI or LCIA phases to help determine the significant 

issues found in the results and presented in previous sections 

of this report. A contribution analysis was applied for the 

interpretation phase of this LCA study. Contribution analysis 

examines the contribution of life-cycle stages (A1 and A3), 

unit process contributions in a multi-unit manufacturing 

process, and specific substances that contribute an impact.
Research Paper FPL–RP–706

20

8.2 Life-Cycle Phase Contribution Analysis

For GW impact, 41% of the CO2 equivalent emissions 

come from producing redwood lumber (A3), with 40% and 

19% assigned to extraction (A1) and transportation (A2), 

respectively (Table 13). Within A3, 70% of GWP impact 

was from the contribution from lumber drying. Lumber 

production (A3) represented the highest impacts for the 

ozone depletion and fossil fuel depletion environmental 

impact categories. Resource extraction (A1) represented 

the highest impacts in various impact categories including 

eutrophication and formation potential of tropospheric 

ozone. From cradle to gate, freshwater use was also almost 

exclusively consumed during the A3 life-cycle stage 

(Table 13). Most of the renewable fuels were used in the 

A3 life-cycle stage (Tables 14 and 15). Renewable fuels 

represented 69% of total cradle-to-gate (A1-A3) energy 

use (Table 15). Nonrenewable fossil fuel consumption 

cradle-to-gate was 38%, 16%, and 46% for A1, A2, and 

A3, respectively (Table 14). Within the resource extraction 

(A1) life-cycle stage, ~100% of the total energy was 

nonrenewable fuels (Table 15). Biomass energy was 

primarily used in cogeneration and drying lumber in 

kilns (A3) and represented 82% of the total energy for A3 

(Table 15). In summary, cradle-to-gate total energy for 

producing redwood lumber, which includes fuel for process 

heat and equipment and electricity, comes from 29% fossil 

fuels, 0.84% nuclear, 69.15% renewable biomass fuel, and 

0.66% hydro (Table 15).

8.3 Uncertainty Analysis

The uncertainty and sensitivity analyses aim to assess 

the reliability of the results. Some degree of uncertainty 

is present in the results because of the variation among 

different data providers. The uncertainty analysis 

investigates input data variations within the sample of 

production facilities. The uncertainty analysis investigates 

input data variations within the sample of production 

facilities. Statistics for key inventory results, i.e., electricity, 

diesel, natural gas, and wood fuel, are shown in Table 16. 

The standard deviation for each of these factors was 

calculated based on the sample data and was used to 

perform sensitivity analysis on these parameters.

In the sensitivity analysis, significant inventory parameters 

were altered to investigate the effect on the LCIA results. 

In this case, the electricity input, the diesel and gasoline 

inputs, the natural gas input, and the biomass fuel input 

were increased and decreased by 20%. The change in LCIA 

results is presented in Table 17. It shows that a 20% change 

of inputs especially electricity, natural gas, and diesel 

has only minor effects on the results. However, the use 

of woody biomass as fuel can substantially affect certain 

indicators including ozone depletion potential and primary 

energy use (renewable energy).

8.4 Limitations

This LCA was created using industry average data for 

upstream materials. Variation can result from differences in 

supplier locations, manufacturing processes, manufacturing 

efficiency, and fuel type used. This LCA does not report all 

the environmental impacts caused by the manufacturing of 

the product but rather reports the environmental impacts for 

those categories with established LCA-based methods to 

track and report. Unreported environmental impacts include 

(but are not limited to) factors attributable to human health, 

land-use change, and habitat destruction. To assess the local 

impacts of product manufacturing, additional analysis is 

required.

This LCA report documents the results of a cradle-to-gate 

analysis and is not a comparative assertion, which is defined 

as an environmental claim regarding the superiority or 

equivalence of one product versus a competing product that 

performs the same function. This LCA does not make any 

statements that the product covered by the LCA is better or 

worse than any other product.

9 Treatment of Biogenic Carbon

Forests are understood as a natural system with multiple 

functions, the production function of timber being one 

of them. Therefore, natural growth and decay processes, 

including natural disturbances, are not attributable to 

the production function of forests and are therefore 

not considered in LCA. Harvesting operations lead to 

temporal decreases in forest carbon pools in the respective 

stand. Impacts on forest carbon pools resulting from 

the sustainable or unsustainable management of forests, 

however, cannot be defined or assessed on the stand level 

but require the consideration of carbon pool changes on 

the landscape level, i.e., the level on which management 

decisions are made. Resulting from the fundamental 

principle of sustainable forest management to preserve the 

production function of forests, total forest carbon pools 

can be considered stable (or increasing) under sustainable 

forest management. This is because temporal decreases of 

forest carbon pools resulting from harvesting on one site are 

compensated by increases of carbon pools on other sites, 

forming together the forest area under sustainable forest 

management.

It is acknowledged that excessive extraction of slash, litter, 

or roots for the purpose of bioenergy generation can lead to 

decreases in forest carbon pools. These activities, however, 

are not causally linked to the extraction of timber for the 

material use of wood. Effects on forest carbon pools related 

to the extraction of slash, litter, or roots are not attributable 

to the material use of wood and are therefore not considered 

in this document.

To reflect the biogenic nature of wood, its renewability, and 

its potential carbon neutrality, the system boundary between 
Cradle-to-Gate Life-Cycle Assessment of Redwood Lumber in the United States

21

Table 13—Cradle-to-gate redwood lumber LCIA contribution analysis results for A1-resource extraction, 

A2-transporation, and A3-redwood lumber production

Reporting category and indicator name Abbreviation Unit Total A1 A2 A3

Core mandatory impact indicator

Global warming potential – TRACI 2.1 GWPTRACI kg CO2e 100% 40% 19% 41%

Depletion potential of the stratospheric ozone layer ODP kg CFC11e 100% 1% 0% 99%

Acidification potential of soil and water sources AP kg SO2e 100% 52% 11% 37%

Eutrophication potential EP kg Ne 100% 46% 9% 45%

Formation potential of tropospheric ozone SFP kg O3e 100% 57% 10% 33%

Abiotic depletion potential for fossil resources (ADP fossil) ADPf MJ, NCV 100% 39% 17% 44%

Fossil fuel depletion FFD MJ surplus 100% 38% 16% 45%

Use of primary resources

Renewable primary energy carrier used as energy RPRE MJ, NCV 100% 0% 0% 100%

Renewable primary energy carrier used as material RPRM MJ, NCV 100% 0% 0% 100%

Nonrenewable primary energy carrier used as energy NRPRE MJ, NCV 100% 38% 16% 46%

Nonrenewable primary energy carrier used as material NRPRM MJ, NCV — — — —

Secondary material, secondary fuel and recovered energy

Secondary material SM kg — — — —

Renewable secondary fuel RSF MJ, NCV 100% 0% 0% 100%

Nonrenewable secondary fuel NRSF MJ, NCV — — — —

Recovered energy RE MJ, NCV — — — —

Mandatory inventory parameters

Consumption of freshwater resources FW m3 100% 0% 0% 100%

Indicators describing waste

Hazardous waste disposed HWD kg — — — —

Nonhazardous waste disposed NHWD kg 100% 0% 0% 100%

High-level radioactive waste, conditioned, to final repository HLRW m3 100% 0% 0% 100%

Intermediate- and low-level radioactive waste, conditioned, 

to final repository

ILLRW m3 100% 0% 0% 100%

Components for re-use CRU kg — — — —

Materials for recycling MR kg 100% 0% 0% 100%

Materials for energy recovery MER kg — — — —

Recovered energy exported from the product system EE MJ, NCV — — — —

Table 14—Cradle-to-gate redwood lumber LCIA energy use contribution 

analysis results by fuel type for A1-resource extraction, A2-transporation, 

and A3-redwood lumber production

Unit Total A1 A2 A3

Nonrenewable, fossil MJ 100.00% 38.98% 16.70% 44.32%

Nonrenewable, nuclear MJ 100.00% 0.25% 0.00% 99.75%

Nonrenewable, biomass MJ 100.00% 0.04% 0.00% 99.96%

Renewable, biomass MJ 100.00% 0.00% 0.00% 100.00%

Renewable, wind, solar, geothermal MJ 100.00% 0.07% 0.00% 99.93%

Renewable, water MJ 100.00% 1.60% 0.00% 98.40%
Research Paper FPL–RP–706

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Table 15—Cradle-to-gate redwood lumber LCIA energy use contribution 

analysis results for A1-resource extraction, A2-transporation, and 

A3-redwood lumber production

Unit Total A1 A2 A3

Nonrenewable, fossil MJ 29.00% 99.88% 100.00% 15.33%

Nonrenewable, nuclear MJ 0.84% 0.02% 0% 1.00%

Nonrenewable, biomass MJ 0.00% 0% 0% 0%

Renewable, biomass MJ 69.15% 0.01% 0% 82.48%

Renewable, wind, solar, geothermal MJ 0.36% 0% 0% 0.43%

Renewable, water MJ 0.66% 0.09% 0% 0.77%

100.00% 100.00% 100.00% 100.00%

Table 16—Uncertainty analysis of selected inventory results

Inventory parameter Units

Sample 

mean

Standard 

deviation

Sample 

minimum

Sample 

maximum

Electricity – A3 input kWh 58.16 17.88 32.28 72.05

Diesel – A3 input L 2.49 0.60 1.65 2.98

Gasoline – A3 input L 0.08 0.06 0.00 0.12

Natural gas – A3 input m3 2.47 4.41 0.00 9.35

Wood fuel – A3 input kg 104.59 78.98 0.00 167.51

Transport distance – A2 input t-km 73.25 19.36 46.69 88.55

nature and the product system under study is defined as 

follows:

• Wood entering the product system from nature accounts 

for the energy content and the biogenic carbon content as 

material inherent properties.

• All technical processes related to forestry operations 

intended to produce timber (e.g., stand establishment, 

tending, thinning(s), harvesting, establishment, and 

maintenance of forest roads) are considered within the 

system boundary and are subject to coproduct allocations 

as outlined in the reference PCR (UL Environment 2019).

• Potential implications caused by the unknown origin of 

wood or unsustainably produced timber are considered.

• Human-induced impacts on forest carbon pools resulting 

in deforestation are included. In this study, the redwood 

forests that supplied logs to the sawmills are Sustainable 

Forestry Initative (SFI) and Forest Stewardship Council 

(FSC) certified and managed sustainably. Deforestation 

does not occur in the redwood forests from which the logs 

were procured.

Because the degradation of forest carbon pools resulting 

from unsustainable management of forests cannot be 

attributed to a specific log but is a process on a landscape 

level, the effect of forest degradation is considered by not 

assuming carbon neutrality. In the case of land-use changes 

from forests to other land uses (e.g., deforestation), the loss 

of carbon in the forest carbon pools are to be considered. 

Consideration of the biogenic carbon neutrality of wood is 

valid for North American wood products because national 

level inventory reporting shows overall increasing and/

or neutral forest carbon stocks in recent years (FAO 2015, 

Oswalt and others 2019, Sahoo and others 2019).

Using this method to determine a value, –1,439 kg CO2e 

(A1) was removed in the production of 1 m3 of redwood 

lumber (Table 18). That same 1 m3 of lumber stores 

190 kg of carbon or +697.3 kg CO2e (C3/C4). The 

coproducts produced during lumber production account for 

an additional +142.5 kg CO2e (A3) for a total “emission” 

in wood product leaving the system boundary of 

+839.2 kg CO2e. The combustion of wood fuel emitted 

600.2 kg CO2e. In summary, total removals were 

–1,440.30 kg CO2e and total “emissions” were 

+840.12 kg CO2e from cradle-to-gate (A1–A3) (Table 18). 

In accordance with ISO 21930, emission from packaging 

(BCEK) is reported in A5 and emission from the main 

product is reported in C3/C4. The system boundary for this 

LCA only includes module A1–A3.

10 Discussion

In 2014, Bergman and others (2014a) performed a gate-togate LCA of dry redwood lumber, which was generally used 

to make decking, and used 2010 survey data collected from 

redwood sawmills from the same region. Table 19 shows 

the comparison between the previous study by Bergman 

and others (2014a) and this study (2017 data). There was a 

30% increase in total primary energy use in the production 

of redwood lumber in this study (1,738 MJ/m3) compared 
Cradle-to-Gate Life-Cycle Assessment of Redwood Lumber in the United States

23

Table 17—Sensitivity analysis (mass allocation)

Log transport 

distance Diesel Gasoline Electricity Natural gas Woody biomass

Impact indicator Unit

Baseline 

results –20% +20% –20% +20% –20% +20% –20% +20% –20% +20% –20% +20%

GWPTRACI kg CO2e 37.81 –6.40% 6.40% –1.71% 1.71% –0.08% 0.08% –3.08% 3.12% –3.23% 3.23% –2.17% 2.18%

ODP kg CFC11e 7.42E–07 –0.01% 0.01% –0.16% 0.16% –0.01% 0.01% –5.70% 5.77% –0.03% 0.03% –9.11% 9.12%

AP kg SO2e 0.38 –3.77% 3.77% –2.22% 2.22% –0.09% 0.09% –3.65% 3.70% –0.24% 0.24% –3.50% 3.51%

EP kg Ne 0.03 –3.08% 3.08% –2.49% 2.49% –0.10% 0.10% –3.08% 3.11% –0.39% 0.39% –4.57% 4.58%

SFP kg O3e 1.11E+01 –3.56% 3.56% –2.49% 2.49% –0.10% 0.10% –2.54% 2.57% –0.21% 0.21% –3.77% 3.77%

ADPf MJ, NCV 526.52 –5.73% 5.73% –1.66% 1.66% –0.09% 0.09% –3.24% 3.28% –3.26% 3.26% –2.17% 2.18%

FFD MJ surplus 82.27 –5.63% 5.63% –1.59% 1.59% –0.08% 0.08% –3.33% 3.37% –3.47% 3.47% –2.13% 2.13%

RPRE MJ, NCV 1,353.03 0.00% 0.00% 0.00% 0.00% 0.00% 0.00% –7.89% 7.98% 0.00% 0.00% –12.60% 12.61%

NRPRE MJ, NCV 609.27 –5.26% 5.26% –1.54% 1.54% –0.08% 0.08% –3.53% 3.57% –3.13% 3.13% –2.67% 2.67%
Research Paper FPL–RP–706

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Table 18—Biogenic carbon inventory parameters

Additional inventory parameters Abbreviation Unit Total A1 A2 A3 A5 C3/C4

Biogenic carbon removal from product BCRP kg CO2 –1439.35 –1439.35 — — — —

Biogenic carbon emission from products 

(including residues and lumber)

BCEP kg CO2 839.17 — — 142.51 — 696.67

Biogenic carbon removal from packaging BCRK kg CO2 –0.95 — — –0.95 — —

Biogenic carbon emission from packaging BCEK kg CO2 0.95 — — — 0.95 —

Biogenic carbon emission from cogeneration 

[internal heat and electricity use]

BCEW kg CO2 192.49 — — 192.49 — —

Biogenic carbon emission from cogeneration 

(external electricity)

BCEW kg CO2 407.68 — — 407.68 — —

Net biogenic carbon emission kg CO2 0

Table 19—LCIA comparison between previous data (Bergman and others 2014a, based 

on 2010 industry surveys) and current study data (based on 2017 industry surveys) on 

redwood lumber production in northern California, USA

Impact category Unit

Current study 

based on 2017 

production dataa

Past study 

based on 2011 

production dataa Percentage 

change

Ozone depletion potential kg CFC11e 8.07E–07 3.69E–06 –78

Global warming potential, fossil kg CO2 eq 22.81 57.4 –60

Eutrophication potential kg N eq 5.79E–02 2.34E–02 148

Smog potential kg O3 eq 4.46 6.61 –33

Nonrenewable fossil and nuclear MJ 357.78b

(361.01c)

1,023 –65

Renewables (solar, wind, hydro, 

geothermal, and biomass)

MJ 1,354.49b

(1,377.16c

)

317 327

Freshwater L 195.53 29.26 568 a

For comparison purposes, cumulative values of A2 and A3 stages of the redwood lumber life cycle were 

considered.

b

Cumulative energy demand for the A2 and A3 stages were estimated considering lower heating value.

c

Cumulative energy demand for the A2 and A3 stages were estimated considering higher heating value.

with the previous gate-to-gate study (1,340 MJ/m3 using the 

higher heating value of all fuel–energy inputs) (Bergman 

and others 2014a). Moreover, in this study, there was a 65% 

decrease in the use of nonrenewable and a 327% increase 

in the use of renewable energy compared with the previous 

study. In this study, the residues generated from the sawmill 

were burned in the cogeneration unit to produce renewable 

electricity, which was mostly used on-site at the sawmill 

(24% of total electricity production) and the rest was 

exported to the local grid. A part of the total heat exhausted 

from the cogeneration unit was used for drying redwood 

lumber (12% of the total heat generated) with excess heat 

released to the environment, i.e., waste heat. Despite higher 

total energy use, the total cradle-to-gate GHG emissions 

were decreased by 78% because of the use of renewable 

electricity and heat from woody biomass. There was a 568% 

increase in water usage because of electricity produced in 

cogeneration being used internally.

11 Completeness and 

Consistency Checks

The completeness and consistency checks and sensitivity 

help to establish and enhance confidence in the study. 

These improve the reliability of the results of the LCA 

study, including the significant issues identified in the 

interpretation.

The objective of the completeness check is to ensure that all 

relevant information and data needed for the interpretation 

are available and complete. Three selected information 

modules (harvesting and forest management, resource and 

material transportation, and manufacturing of redwood 

lumber) were checked for data completeness including all 

elements such as raw and ancillary material input, energy 

input, transportation, water consumption, product and 

coproduct outputs, emissions to air, water, and land, and 

waste disposal. All the input and output data were found to 

be complete, and no data gaps were identified.
Cradle-to-Gate Life-Cycle Assessment of Redwood Lumber in the United States

25

The objective of the consistency check is to determine if the 

assumptions, methods, models, and data are consistent with 

the goal and scope of the study. Through a rigorous process, 

consistency is ensured to fulfill the goal of the study in 

terms of assumptions, methods, models, and data quality 

including data source, accuracy, data age, time-related 

coverage, technology, and geographical coverage.

12 Conclusions

The cradle-to-gate LCA for redwood lumber includes the 

LCI of forest resources, which relies on secondary and 

tertiary data, and the LCI of manufacturing, which relies 

on primary survey data and secondary data for process 

inputs such as natural gas, diesel, and electricity. The survey 

results were from representative operations in the northern 

California region that produce redwood lumber. The survey 

data were representative of the lumber sizes and production 

volumes consistent with trade association production 

data. By surveying 0.403 million m3 of redwood lumber 

production, this study represents 66.6% of the total U.S. 

production for 2017, which was 0.605 million m3.

Using methods of drying wood that are less energyintensive than heated kilns can result in large decreases in 

environmental impacts. Because redwood sawmills use 

minimal kiln-drying (and when they do, the source for 

heating is from woody biomass), GHG emissions from the 

forest extraction (resources) are large relative to that from 

manufacturing (Puettmann and Wilson 2005, Puettmann 

and others 2010). In addition, on-site emissions to land and 

water are small. Mill on-site airborne emissions originated 

mainly at the boiler and dryer. Electrical energy use was 

greatest in the sawmill with overall energy use and on-site 

emissions dominated by the drying process.

Energy consumption was mostly consistent with the 

previous redwood decking study except for items such 

as higher woody biomass consumption and cogeneration 

electricity production (Bergman and others 2013, 

2014a). Still, woody biomass consumption drove the 

high percentage of energy consumption for the product 

manufacturing stage for both studies. For this study, 

lumber production (A3) consumed 84% of the total energy, 

whereas 11% went to forest operations and 5% to transport. 

Energy generated by renewable fuels, such as woody 

biomass, represented about 69% of the total energy from 

cradle to gate. Total nonrenewable fuel use was 29% of 

the total energy from cradle to gate. For nonrenewable 

fuel contribution, forestry operations and raw material 

transportation consumed 39% and 17%, respectively 

(Table 13).

13 Critical Review

13.1 Internal Review

The purpose of the internal review of this LCA report was 

to check for errors and conformance with the PCR prior to 

submittal for external review. The technical and editorial 

comments of the reviewers were carefully considered and, 

in most instances, incorporated into the final document. The 

USDA Forest Service, Forest Products Laboratory (FPL), 

addressed the internal review comments, as appropriate, and 

maintains a record of all comments and responses for future 

reference.

13.2 External Review

The external review process was intended to ensure 

consistency between the completed LCA and the principals 

and requirements of the International Standards on LCA 

(ISO-14044) and the PCR for North American Structural 

and Architectural Wood Products (UL Environment 2018). 

Following FPL’s internal review evaluation, documents 

were submitted to UL Environment for independent external 

review. The independent external review performed by 

UL Environment was conducted by Dr. Thomas P. Gloria, 

Ph.D., Industrial Ecology Consultant.

13.3 Units

Table 20 gives some information about converting from 

board feet to cubic meters.

14 References

Abergel, T.; Dean, B.; Dulac, J. 2017. Towards a zeroemission, efficient, and resilient buildings and construction 

sector: Global Status Report 2017. Paris, France: UN 

Environment, International Energy Agency.

Bare, J.C. 2011. TRACI 2.0: The tool for the reduction and 

assessment of chemical and other environmental impacts 

2.0. Clean Technologies and Environmental Policy. 13(5): 

687-696.

Bergman, R. 2010. Chapter 13. Drying and control of 

moisture content and dimensional changes. In: General 

Technical Report FPL-GTR-190. Wood handbook—Wood 

as an engineering material. Madison, WI: U.S. Department 

of Agriculture, Forest Service, Forest Products Laboratory.

Table 20—Wood conversion

To convert from to Multiply by

Board feet log scale, international rule 1/4 m3 0.0002

Board feet rough-green or rough-dry lumber m3 Varies by lumber size, based on actual dimensions

Board feet planed lumber m3 0.00162 for 2 by 6; varies by lumber size
Research Paper FPL–RP–706

26

Bergman, R.D.; Bowe, S.A. 2008. Environmental impact 

of producing hardwood lumber using life-cycle inventory. 

Wood and Fiber Science. 40(3): 448-458.

Bergman, R.; Bowe S. 2010. Environmental impact of 

manufacturing softwood lumber determined by life-cycle 

inventory. Wood and Fiber Science. 42(CORRIM Special 

Issue): 67-78.

Bergman, R.; Bowe S. 2012. Life-cycle inventory of 

manufacturing hardwood lumber in the southeastern United 

States. Wood and Fiber Science. 44(1): 71-84.

Bergman, R.; Taylor, A. 2011. EPD-environmental product 

declarations for wood products—an application of life cycle 

information about forest products. Forest Products Journal. 

61(3): 192-201.

Bergman, R.; Han, H.-S.; Oneil, E.; Eastin, I. 2013. Lifecycle assessment of redwood decking in the United States 

with a comparison to three other decking materials. https://

corrim.org/lcas-on-wood-products-library/ Corvalis, 

OR: Consortium for Research on Renewable Industrial 

Materials.

Bergman, R.D.; Oneil, E.; Eastin, I.L.; Han, H.S. 2014a. 

Life cycle impacts of manufacturing redwood decking 

in northern california. Wood and Fiber Science. 46(3): 

322-339.

Bergman, R.; Puettmann, M.; Taylor, A.; Skog, K.E. 2014b. 

The carbon impacts of wood products. Forest Products 

Journal. 64(7-8): 220-231.

Briggs, D.G. 1994. Forest products measurements and 

conversion factors: with special emphasis on the US Pacific 

Northwest. Seattle, WA: College of Forest Resources, 

University of Washington.

Bringezu, S.; Ramaswami, A.; Schandl, H.; O’Brien, M.; 

Pelton, R.; et al. 2017. Assessing global resource use: a 

systems approach to resource efficiency and pollution 

reduction. International Resource Panel. Nairobi, Kenya: 

United Nations Environment Programme.

Canadell, J.G.; Raupach, M.R. 2008. Managing forests for 

climate change mitigation. Science. 320 (5882): 1456-1457.

FAO. 2015. Global forest resources assessment 2015. 

FAO Forestry Paper No. 1. Rome, Italy: The Food and 

Agriculture Organization of the United Nations.

FPL. 2010. Wood handbook—Wood as an engineering 

material. General Technical Report FPL-GTR-190. 

Madison, WI: U.S. Department of Agriculture, Forest 

Service, Forest Products Laboratory.

Glass, S.V.; Zelinka, S.L. 2010. Chapter 4. Moisture 

relations and physical properties of wood. In: FPLGTR-190. Wood handbook—Wood as an engineering 

material. Madison, WI: U.S. Department of Agriculture, 

Forest Service, Forest Products Laboratory.

Han, H.S.; Oneil, E.; Bergman, R.D.; Eastin, I.L.; Johnson, 

L.R. 2015. Cradle-to-gate life cycle impacts of redwood 

forest resource harvesting in northern California. Jouranl of 

Cleaner Production. 99: 217-229.

ISO. 2006a. ISO-14040. Environmental management: life 

cycle assessment; Principles and Framework. Geneva, 

Switzerland: International Organization for Standardization.

ISO. 2006b. ISO-14044. Environmental Management: Life 

Cycle Assessments: requirements and guidelines. Geneva, 

Switzerland: International Organization for Standardization.

ISO. 2017. ISO-21930. Sustainability in buildings and civil 

engineering works — core rules for environmental product 

declarations of construction products and services. Geneva, 

Switzerland: International Organization for Standardization.

LTS. 2017. DataSmart LCI package (US-EI SimaPro® 

Library). https://ltsexperts.com/services/software/

datasmart-life-cycle-inventory/. Huntington, VT: Long Trail 

Sustainability.

Malmsheimer, R.W.; Bowyer, J.L.; Fried, J.S.; Gee, E.; 

Izlar, R.; Miner, R.A.; Munn, I.A.; Oneil, E.; Stewart, W. 

2011. Managing forests because carbon matters: integrating 

energy, products, and land management policy. Journal of 

Forestry. 109(7S): S7-S50.

Matos, G.R. 2017. Use of raw materials in the United States 

from 1900 through 2014, Fact Sheet. Reston, VA: U.S. 

Department of the Interior, U.S. Geological Survey.

Miles, P.D.; Smith, W.B. 2009. Specific gravity and other 

properties of wood and bark for 156 tree species found in 

North America. Res. Note NRS-38. Newtown Square, PA: 

U.S. Department of Agriculture, Forest Service, Northern 

Research Station. 35 p.

Nielson, R.; Dobie, J.; Wright, D. 1985. Conversion 

factors for the forest products industry in western Canada. 

Vancouver, B.C., Canada: Forintek Canada Corp., Western 

Laboratory.

NIST. 2015. American softwood lumber standard: voluntary 

product standard PS 20-15. Gaithersburg, MD: U.S. 

Department of Commerce National Institute of Standards 

and Technology. 51 p.

Oliver, C.D.; Nassar, N.T.; Lippke, B.R.; McCarter, J.B. 

2014. Carbon, fossil fuel, and biodiversity mitigation with 

wood and forests. Journal of Sustainable Forestry. 33(3): 

248-275.

Oswalt, S.N.; Smith, W.B.; Miles, P.D.; Pugh, S.A. 2019. 

Forest resources of the United States, 2017: a technical 

document supporting the Forest Service 2020 RPA 

Assessment. Gen. Tech. Rep. WO-97. Washington, DC: 

U.S. Department of Agriculture, Forest Service, Washington 

Office. 223 p.
Cradle-to-Gate Life-Cycle Assessment of Redwood Lumber in the United States

27

Pré-Consultants. 2017. SimaPro life-cycle assessment 

software package, version 8.5.2. Amersfoort, the 

Netherlands: Pré-Consultants.

Puettmann, M.E.; Milota, M. 2017. Life-cycle assessment 

for wood-fired boilers used in the wood products industry. 

Forest Products Journal. 67(5-6): 381-389.

Puettmann, M.E.; Wilson, J.B. 2005. Life-cycle analysis 

of wood products: cradle-to-gate LCI of residential wood 

building materials. Wood and Fiber Science. 37(CORRIM 

Special Issue): 18-29.

Puettmann, M.E.; Bergman, R.; Hubbard, S.; Johnson, L.; 

Lippke, B.; Oneil, E.; Wagner, F.G. 2010. Cradle-to-gate 

life-cycle inventory of US wood products production: 

CORRIM Phase I and Phase II products. Wood and Fiber 

Science. 42(CORRIM Special Issue): 15-28.

Sahoo, K.; Bergman, R.; Alanya-Rosenbaum, S.; Gu, 

H.; Liang, S. 2019. Lifecycle assessment of forest-based 

products: a review. Sustainability. (11): 4722.

Sathre, R.; O’Connor, J. 2010. Meta-analysis of greenhouse 

gas displacement factors of wood product substitution. 

Environmental Science & Policy. 13(2): 104-114.

Save The Redwoods League. 2019. A momentous year: 

great strides toward a 100-year vision. Annual Report 2018-

19. San Francisco: Save The Redwoods League. https://

www.savetheredwoods.org/wp-content/uploads/AnnualReport-2018-19-web.pdf.

Simpson, W.T. 1991. Dry kiln operator’s manual. Agric. 

Handbook AH-188. Madison, WI: U.S. Department of 

Agriculture, Forest Service, Forest Products Laboratory.

UL Environment. 2018. Product category rules for buildingrelated products and services in: Brazil, China, Europe, 

India, Japan, Korea, North America, South East Asia. Part 

A: Life Cycle Assessment calculation rules and report 

requirements. UL Environment, Washington, DC.

UL Environment. 2019. Product category rule (PCR) 

guidance for building-related products and services: 

Part B: Structural and architectural wood products EPD 

requirements. Washington, DC: UL Environment.

15 Glossary of Terms

Allocation: A way of dividing emissions and resource use 

among the different products of a process. The partitioning 

can be made on a weight basis, energy content, or economic 

value.

Board foot (BF): The basic unit of measurement for 

lumber. One board foot is equal to a 1-in. board, 12 in. wide 

and 1 ft long (1 in. = 25.4 mm, 1 ft = 0.31 m).

Cradle-to-gate: LCA model that includes the upstream part 

of the product life cycle, i.e., all steps from raw material 

extraction to product at the factory gate.

Cubic recovery: A measure of the actual cubic volume 

of lumber recovered from the original net cubic log scale 

volume.

Declared unit: Quantity of a wood building product for use 

as a reference unit, e.g., mass, volume, for the expression of 

environmental information needed in information modules.

Functional unit: Expresses the function of the studied 

product in quantitative terms and serves as basis for 

calculations. It is the reference flow to which other flows in 

the LCA are related. It also serves as a unit of comparison in 

comparative studies.

Life-cycle assessment (LCA): Method for the 

environmental assessment of products covering their life 

cycle from raw material extraction to waste treatment.

Life-cycle inventory (LCI): LCA study that goes as 

far as an inventory analysis but does not include impact 

assessment.

Life-cycle impact assessment (LCIA): Phase of an LCA 

study during which the environmental impacts of the 

product are assessed and evaluated.

Lumber recovery factor (LRF): The volume of lumber 

recovered (in board feet) per cubic foot of log processed.

Overrun: The volume of lumber actually obtained from a 

log in excess of the estimated volume of the log, based on 

the log scale.

Product category rules (PCR): Set of specific rules, 

requirements, and guidelines for the development of 

type III environmental declarations for one or more 

product categories (ISO 14025, ISO 21930).

System boundary: A set of criteria that specifies which 

unit processes are part of a product system (adapted from 

ISO 14044).
Research Paper FPL–RP–706

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Appendix A—Production Facility Survey Questionnaires

Appendix A: Production Facility Survey Questionnaires

CORRIM SURVEY

The Consortium for Research on Renewable Industrial Materials (CORRIM)

Redwood lumber-2017

Thank you for giving us the opportunity to work with you on a project involving the long-term viability and 

profitability of the U.S. wood products industry. Results from this project will be an excellent marketing tool for 

the redwood lumber industry particularly in the green building industry. A growing demand for building projects 

that use products with lower environmental burdens and energy-efficient materials has spurred a green movement 

in the construction industry. 

As a member of the U.S. forest products industry, you know that using wood is a sensible choice because wood is 

renewable and often poses fewer burdens to the environment than substitute materials. Many consumers do not 

understand this. With your input, we can test the theory that redwood lumber poses less negative impacts to the 

environment than substitute materials such as plastic, concrete, steel and others do. Completed projects of this 

type have shown that wood products to be a sustainable and sound environmental choice over non-wood product 

alternatives. 

This questionnaire focuses on annual production, annual energy use and generation, annual material inputs and 

outputs, and annual environmental emissions for redwood lumber manufactured in California. Regarding the 

questionnaire, our focus is on process information because this data is vital for precise and accurate results. 

Additional details may be requested later. We realize that you may not have all the information requested, but the 

data you are able to provide will be appreciated.

Strict confidentiality will be maintained for all companies that supply data

Company Name: _________________________________

Facility Address: _________________________________

 _________________________________

Contact Person: _________________________________

Telephone: ( ) Fax: ( )_______ 

Contact email: _________________________________

Please direct questions and send complete questionnaires to:

Kamalakanta (KK) Sahoo

USDA FS Forest Products Laboratory

One Gifford Pinchot Dr

Madison, WI 53726-2398

Phone (608) 231-9272 / Fax (608) 231-9508 

Email: ksahoo@fs.fed.us
Cradle-to-Gate Life-Cycle Assessment of Redwood Lumber in the United States

29

2

PART I: OPERATION OVERVIEW

GENERAL INFORMATION (Please provide responses for all requested 

information)

1. Reporting Year: ________ Starting Month: ________ Ending Month: ________

2. Log scale: Dolye, International, Scribner, Weight basis (circle one)

3. How many days did your mill operate for the selected reporting year? _________Days/Year

4. How many production shifts per day for the selected reporting year? __________Shifts/Day

5. Does your mill have the following:

q log storage 

o dry deck

o sprinkled deck

o pond

o other: _______________

q log handling

o log sorter/merchandizer

o debarker

q sawmill

o head rig(s): how many:_____ 

o band saw: how many:_____

o circular saw: how many:_____

o resaws: how many:______

o edgers: how many:______

o edger optimizer

o trimmer optimizer 

o trimmer

o sorter, # bins:______

o sticker stacker

o emission control device(s)

q dryers and kilns

o air drying yard: Capacity_________

o conventional steam: Capacity________

o high temperature steam: Capacity________

o direct-fired: Capacity________

o dehumidification: Capacity________

o transfer car system: Capacity________

q boiler

o wood-fired boiler

o gas-fired boiler (natural or propane)

o oil-fired boiler

o cogeneration facility (electricity)

o emission control device(s)

q planers

o planer

o in-line moisture meter

o grading station

o trimmer

o end paint/seal

q other mill equipment

PART II: TOTAL MILL MATERIAL & ENERGY INPUTS & OUTPUTS

6. Average log diameter: ____________ inches

7. Range of log diameter: ______to______ inches

8. Average log length: ______________feet

9. Volume of incoming logs during the reporting year: _____________ thousand bf

10. Volume of logs sold to outside firms during the reporting year: _________ thousand bf

11. Volume of logs sent to your sawmill during the reporting year: ________ thousand bf
Research Paper FPL–RP–706

30

3

Please complete the following table to provide your facilities annual lumber production levels for the reporting 

year by product size. Please add more rows if necessary. Note – only report rough green lumber production by 

size for products when sold or transferred from your facility. We will be completing a mass balance (logs in vs. 

lumber and co-products out) for your mill, so we first need to know your lumber production – so if it leaves your 

facility, we need to track it. We provided an example in the table of a mill that produces annually 60 million bf of 

nominal 2x6s. The numbers for 2x6 lumber are the focus of this project but we need values for the other sizes to 

determine the mass balance accurately.

ANNUAL MILL PRODUCTION

Nominal 

Lumber 

Size

MMbf for 

reporting 

yr.

Surfaced-Green 

(MC=30%)1

Rough-Dry 

(MC=15%)1

Surfaced-Dry 

(MC=15%)1

Rough Green 

(Sold or 

transferred only) 

(MC=30%)1

Price

($/Mbf)

Percentage

(%)

2x6 e.g. 45 X, MC=35% e.g.600 75%

2x6 e.g. 10 X, MC=19% e.g.700 16.7%

2x6 e.g. 5 X, MC=19% e.g.900 8.3%

Total e.g. 60 e.g.45 e.g. 10 e.g. 5 e.g.640 100%

Please complete for your mill below (add more rows if required)

1x4

1x4

1x4

5/4x6

5/4x6

5/4x6

2x4

2x4

2x4

2x6

2x6

2x6 1 Change MC as appropriate More rows on next sheet (over)

Nominal 

Lumber 

Size

MMbf for 

reporting yr.

Surfaced-Green 

(MC=30%)1

Rough-Dry 

(MC=15%)1

Surfaced-Dry 

(MC=15%)1

Rough Green (Sold or 

transferred only) 

(MC=30%)1

Price

($/Mbf) Percentage

(%)

2x8

2x8

2x8

2x10

2x10

2x10

2x12

2x12

2x12

2x14

2x14
Cradle-to-Gate Life-Cycle Assessment of Redwood Lumber in the United States

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4

2x14

4x4

4x4

4x4

4x6

4x6

4x6

4x8

4x8

4x8

Other

Other

Other

Other

Other

Other

Total 100%

1 Change MC as appropriate

ANNUAL RESOURCE TRANSPORTATION DATA: (transporting material to and from your 

sawmill)

Material

No. of 

deliveries

Average net 

weight of load 

(tons)

Average oneway distance 

(miles)

Transportation type

(choose one)

Percent 

empty 

backhaul

Logs Rail/Trucking

Purchased wood fuel (if any) Rail/Trucking

Boiler Chemicals Small/Large Truck

12. For each of the co-products produced at your plant, please indicate the weight (tons) of annual production for 

the reporting period that are shipped to other users, used internally as fuel or for the production of another coproduct at your facility, stockpiled for future use or land filled (estimates are acceptable). If zero, enter a dash 

(-). Please state units if other than tons like cubic yards. The final column (Total Quantity) should equal the 

sum of the individual rows.

Estimate amount of wood residue produced per thousand bf of redwood lumber ______tons/Mbf

Co-products and ByProducts

Moisture

Content

(wet basis)

Sold 

(Shipped)

Used 

Internally

(as fuel)

Used 

Internally

(other uses)

Landfill Inventory Total

Quantity

(%) tons tons tons tons tons tons

Chips, green

Sawdust, green

Bark, green

Edging strips, green
Research Paper FPL–RP–706

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5

Shavings, green

Hogged material, green

Sawdust, dry

Shavings, dry 

Hogged material, dry

Other

13. If you have installed emission control devices at your mill, please list them by type and the equipment 

controlled by the device.

Boiler #1 Boiler #2 Sawmill Dry Kiln Planermill Logyard

Type of Device

Equipment controlled

Electrical Use1, kWh

Type of emissions controlled

14. Are you processing material from other facilities (e.g. kiln drying lumber or planing rough green or kiln dried 

lumber from other mills)?

_________Yes; ___________No;

If Yes, please specify the quantity per process for the selected reporting year:

Kiln drying lumber from other mills (MMbf/yr) _______

Planing rough green lumber from other mills (MMbf/yr) _______

Planing kiln-dried lumber from other mills (MMbf/yr) _______

Short description of redwood lumber production process:

The sawmill complex is divided into six process units: (1) log yard, (2) sawing, (3) drying, (4) planing, (5) boiler 

or co-generation equipment (energy generation) and (6) emission control (if applicable)

- Log yard includes all log handling from receiving logs at mill gate up to breakdown of the log

- Sawing includes the breakdown of the logs into rough green lumber.

- Drying includes stickering, the dry kilns, loading area, and unloading (storage) and air yards.

- Planing includes the unstacker, planer, and packaging areas. Each of these includes transportation to the next 

unit process or plant gate.

- Boiler/co-generation equipment (energy generation) includes fuel storage, transportation, boiler, turbines and 

steam distribution system.

ANNUAL TRANSPORTATION FUEL USE ON-SITE (includes all fuels for yard equipment, 

forklifts, and carriers)

Type Total

Quantity

Percent of total by unit process (percentage or volume)

1. Log Units

yard

2. Sawing 3. Drying 4. Planing 5. Boiler/Cogen

Off-road diesel Gallons

Fuel Oil #6 Gallons

Propane Gallons

Gasoline Gallons

Electricity kWh

Other
Cradle-to-Gate Life-Cycle Assessment of Redwood Lumber in the United States

33

6

ANNUAL BOILER FUEL AND ELECTRICTY USE: (boilers, cogeneration units, etc.)

Boiler Fuel Total Quantity Units Moisture content (if 

applicable)

Wood

Wood boiler fuel produced on-site Tons

Purchased wood boiler fuel Tons

Fossil Fuel 

Natural Gas Thousand ft3

Fuel oil #1(kerosene) Gallons

Fuel oil #2 (heating oil) Gallons

Fuel oil #6 Gallons

Propane Gallons

Electricity for entire facility kWh

Other

Annual electricity use for the following processes (Estimation by percentage or number is ok)

Process kWh % of total

1. Log yard

2. Sawing

3. Kiln drying

4. Planing

5. Boiler/Co-generation

Total 100%

ANNUAL WATER USE

Type Total

Quantity

Percent of total by unit process (percentage or volume)

1. Log Units

yard 2. Sawing 3. Drying 4. Planing 5. Boiler/Cogen

Input

Surface water Gallons

Groundwater Gallons

Municipal water Gallons

Output

Water discharged Gallons

Water recycled Gallons

What percent of water is recycled? ________%

ANNUAL ANCILLARY MATERIALS

Type Total

Quantity

Percent of total by unit process (percentage or volume)

1. Log Units

yard 2. Sawing 3. Drying 4. Planing 5. Boiler/Cogen

Hydraulic Fluid Gallons

Motor Oils Gallons

Greases Pounds

Gasoline Gallons
Research Paper FPL–RP–706

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7

Steel strapping Pounds

Plastic strapping Pounds

Paint Gallons

Corrugated 

cardboard

Pounds

Replacement 

stickers

Pounds

ANNUAL INDUSTRIAL (SOLID) WASTE (material requiring disposal outside of mill)

Type Pounds Percent Landfilled

Pallets (not re-used)

Fly Ash

Bottom ash

General refuse (do not include above materials)

Recycled material

Other

ANNUAL AIR EMISSIONS: (Provide stack test if available)

Type Total

Quantity

Percent of total by unit process (percentage or volume)

1. Log Units

yard 2. Sawing 3. Drying 4. Planing 5. Boiler/Co-gen

Dust Pounds

Total Particulate Pounds

PM2.5 Pounds

PM10 Pounds

Carbon monoxide (CO) Pounds

Carbon dioxide (CO2) Pounds

Acetone Pounds

Acetaldehyde Pounds

Formaldehyde Pounds

Hazardous Air Pollutants 

(HAPS) Pounds

Methanol Pounds

Nitrous oxides (NOx) Pounds

Phenol Pounds

Propionaldehyde Pounds

Sulfur dioxide (SO2) Pounds

Total VOCs Pounds

Others (please list all 

known): Pounds

Other Pounds

Other Pounds

Other Pounds

Other Pounds
Cradle-to-Gate Life-Cycle Assessment of Redwood Lumber in the United States

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8

ANNUAL BOILER CHEMICALS

Boiler Chemicals Total Quantity Units

 Oxygen scavenger

Name_____________________ Gallons

 Corrosion inhibitors

Name_____________________ Gallons

 Scale inhibitors

Name_____________________ Gallons

 pH adjusters

Name_____________________ Gallons

 Anti-foams

Name_____________________ Gallons

 Sludge conditioners

Name_____________________ Gallons

ANNUAL WATER EFFLUENT: (Provide water discharge test if available)

Type Total

Quantity

Percent of total by unit process (percentage or volume)

1.Log Units

yard 2. Sawing 3. Drying 4. Planing 5. Boiler/Co-gen

BOD1 Pounds

COD2 Pounds

Chlorine Pounds

Oil Pounds

Suspended solids Pounds

Dissolved solids Pounds

Phenols Pounds

Others (please list all 

known): Pounds

1 Biological oxygen demand

2 Chemical oxygen demand

DRY KILN INFORMATION (dry kilns are the most energy intensive process for making lumber)

Part of this study will be reviewing energy reduction potentials associated with kiln-drying, the most energy 

intensive aspect of lumber production. Please provide the following details on each of your kilns. If all or 

some kilns are identical simply write “same as Kiln No. X” below the appropriate kiln number. Attach a 

separate sheet if there are more than 5 kilns.

Dry Kilns 1 2 3 4 5

Kiln Capacity (Mbfm) 

Energy Systems

Direct-fired (Y/N)

Fuel type (gas, oil, biomass, etc.)

Capacity (BTU’s / hr.)

Total HP electrical motors (blower, make-up air etc.)

Radiant Heating (coils) (Y/N)

Type (steam, hot oil, hot water)

Kiln Configuration
Research Paper FPL–RP–706

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9

(side loading, single track, double track)

Average age of kilns or year installed

Fan Configuration (line shaft, cross shaft)

No. of fan motors

Dry Kilns (continued) 1 2 3 4 5

Total HP for Kiln

Humidification System (yes/no)

If yes, state type (live steam, water spray)

Vent Heat Exchangers present (Yes/No)

Drying Practices

Initial Moisture Content

Average length of time material remains in airdrying yard (days)

Average Kiln Drying Time for all material (hrs)

Pre-sorting (Yes/No)

If Yes, state type of sorting (by MC, grade, other)

Final Moisture Content

Glossary

Baghouse: Air pollution device which forces gases through a filter thereby capturing gas born particles.

By-product: Material produced during manufacturing that is recycled or used “within system boundaries.”

Bottom ash: Residual by-product of burning coal. Porous, grainy, roughly sand sized particles.

Co-product: A material produced from manufacturing and "sold outside of the system boundary."

Cyclone: A device that uses centrifugal forces to collect waste material.

Dust: Dispersion particles formed in grinding a solid; particles may be small enough to temporarily suspend in 

the air.

Edgings: Pieces of board produced after lumber passes through an edger to achieve desired width.

Electrostatic Precipitator (esp): A type of precipitator which changes the electrical charge on a particle so 

that it can be captured by electrostatic forces.

Emissions: Expulsion of pollutants to air from a source.

Fly ash: Particulate impurities that come from burning coal and other materials.

General refuse: Waste collected from the facility that is mixed with dirt and cannot be sent to the boiler.

HAPs: Hazardous Air Pollutants (carbon oxides, nitrogen oxides, sulfur oxides).

Inorganic material: Material such as sand and other non-solubles.

Industrial waste: Material produced during manufacture requiring disposal out of the “system boundary.” 

Packaging material: Steel strapping, plastic lumber covers, cardboard corners, plastic or paper wrap.

Particulates: By-products of combustion or milling; can be solid or liquid state.

PM10: Standard for measuring solid and liquid particulates in suspension in the atmosphere; particulates are 

defined here as less than 10 micrometers in diameter.

Product: The primary material produced from manufacturing and "sold outside of the system boundary."

Recycled material: Material collected from the manufacturing facility operation that is re-used.

VOCs: Volatile Organic Compounds- produced in incomplete combustion of carbon based compounds; does not 

include methane; examples are oil based paints and gasoline fumes.
Cradle-to-Gate Life-Cycle Assessment of Redwood Lumber in the United States

37

Appendix B—Conversion Factors and Redwood Lumber 

Product Dimensions

Table B1—Conversion factor used to convert thousand board feet (MBF) to cubic meters for 

redwood lumber based on size and type (moisture content and extent of planing)a

Nominal 

dimensionsb Roughgreen

Partially 

roughgreenPartially 

rough-dry

Partially 

roughkiln-dryPlanedgreenPlaneddry

PlanedpartialdryPlanedairseasoned

1 by 2 2.333 1.887 1.748 1.748 1.440 1.327 1.364 1.364

1 by 3 2.318 1.946 1.815 1.815 1.575 1.475 1.516 1.516

1 by 4 2.333 1.987 1.859 1.859 1.642 1.549 1.592 1.592

1 by 5 2.324 1.983 1.855 1.855 1.642 1.549 1.592 1.592

1 by 6 2.318 2.023 1.889 1.889 1.728 1.622 1.668 1.668

1 by 7 2.327 2.028 1.893 1.893 1.728 1.622 1.668 1.668

1 by 8 2.322 2.011 1.882 1.882 1.700 1.604 1.649 1.649

1 by 9 2.328 2.014 1.884 1.884 1.700 1.604 1.649 1.649

1 by 10 2.324 2.038 1.899 1.899 1.751 1.637 1.683 1.683

1 by 12 2.326 2.046 1.911 1.911 1.767 1.659 1.706 1.706

2 by 2 2.380 1.910 1.770 1.770 1.440 1.327 1.364 1.364

2 by 3 2.364 1.969 1.837 1.837 1.575 1.475 1.516 1.516

2 by 4 2.380 2.011 1.881 1.881 1.642 1.549 1.592 1.592

2 by 4 

(1-1/2 by 

3-1/2 actual)

2.380 2.011 1.881 1.881 1.642 1.549 1.592 1.592

2 by 4 

(1-5/8 by 

3-5/8 actual)

2.380 2.011 1.881 1.881 1.642 1.549 1.592 1.592

2 by 5 2.371 2.006 1.877 1.877 1.642 1.549 1.592 1.592

2 by 6 2.364 2.046 1.910 1.910 1.728 1.622 1.668 1.668

2 by 6 

(1-1/2 by 

5-1/2 actual)

2.364 2.046 1.910 1.910 1.728 1.622 1.668 1.668

2 by 7 2.373 2.051 1.915 1.915 1.728 1.622 1.668 1.668

2 by 8 2.368 2.048 1.903 1.903 1.728 1.604 1.649 1.649

2 by 10 2.371 2.061 1.921 1.921 1.751 1.637 1.683 1.683

2 by 12 2.372 2.069 1.933 1.933 1.767 1.659 1.706 1.706

2 by 12 

(1-1/2 by 

11-1/2 actual)

2.372 2.069 1.933 1.933 1.767 1.659 1.706 1.706

3 by 3 2.349 2.058 1.922 1.922 1.767 1.659 1.706 1.706

3 by 4 2.364 2.080 1.960 1.960 1.795 1.721 1.769 1.769

3 by 4 

(2-5/8 by 

3-5/8 actual)

2.364 2.080 1.960 1.960 1.795 1.721 1.769 1.769

3 by 5 2.355 2.075 1.955 1.955 1.795 1.721 1.769 1.769

3 by 6 2.349 2.120 1.994 1.994 1.891 1.803 1.854 1.854

3 by 6 

(2-1/4 by 

5-5/8 actual)

2.349 2.120 1.994 1.994 1.891 1.803 1.854 1.854

3 by 7 2.358 2.124 1.998 1.998 1.891 1.803 1.854 1.854
Research Paper FPL–RP–706

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Table B1—Conversion factor used to convert thousand board feet (MBF) to cubic meters for 

redwood lumber based on size and type (moisture content and extent of planing)a

—con.

Nominal 

dimensionsb Roughgreen

Partially 

roughgreenPartially 

rough-dry

Partially 

roughkiln-dryPlanedgreenPlaneddry

PlanedpartialdryPlanedairseasoned

3 by 8 2.353 2.121 1.985 1.985 1.890 1.782 1.832 1.832

3 by 8 

(2-1/4 by 

7-1/2 actual)

2.353 2.121 1.985 1.985 1.890 1.782 1.832 1.832

3 by 10 2.355 2.135 2.005 2.005 1.915 1.819 1.870 1.870

3 by 12 2.357 2.143 2.017 2.017 1.930 1.842 1.893 1.893

4 by 4 2.380 2.126 2.010 2.010 1.872 1.807 1.857 1.857

4 by 4 

(3-1/2 by 

3-1/2 actual)

2.380 2.126 2.010 2.010 1.872 1.807 1.857 1.857

4 by 4 

(3-3/8 by 

3-3/8 actual)

2.380 2.126 2.010 2.010 1.872 1.807 1.857 1.857

4 by 4 

(3-5/8 by 

3-5/8 actual)

2.380 2.126 2.010 2.010 1.872 1.807 1.857 1.857

4 by 5 2.371 2.121 2.006 2.006 1.872 1.807 1.857 1.857

4 by 6 2.364 2.167 2.046 2.046 1.970 1.893 1.946 1.946

4 by 6 

(3-1/2 by 

5-1/2 actual)

2.364 2.167 2.046 2.046 1.970 1.893 1.946 1.946

4 by 6 

(3-5/8 by 

3-3/8 actual)

2.364 2.167 2.046 2.046 1.970 1.893 1.946 1.946

4 by 7 2.380 2.126 2.010 2.010 1.872 1.807 1.857 1.857

4 by 8 2.380 2.126 2.010 2.010 1.872 1.807 1.857 1.857

4 by 10 2.380 2.126 2.010 2.010 1.872 1.807 1.857 1.857

4 by 12 2.380 2.126 2.010 2.010 1.872 1.807 1.857 1.857

6 by 6 2.380 2.126 2.010 2.010 1.872 1.807 1.857 1.857

6 by 8 2.380 2.126 2.010 2.010 1.872 1.807 1.857 1.857

6 by 10 2.380 2.126 2.010 2.010 1.872 1.807 1.857 1.857

6 by 12 2.380 2.126 2.010 2.010 1.872 1.807 1.857 1.857

8 by 8 2.380 2.126 2.010 2.010 1.872 1.807 1.857 1.857

8 by 10 2.380 2.126 2.010 2.010 1.872 1.807 1.857 1.857

10 by 10 2.380 2.126 2.010 2.010 1.872 1.807 1.857 1.857

10 by 12 2.380 2.126 2.010 2.010 1.872 1.807 1.857 1.857

12 by 12 2.380 2.126 2.010 2.010 1.872 1.807 1.857 1.857

Others 2.380 2.126 2.010 2.010 1.872 1.807 1.857 1.857

a

This table was generated following these references (Nielson and others 1985, Briggs 1994, FPL 2010). b

Nominal measurements for dimensional lumber can be converted to standard metric measurements of the following: 

1 in. = 19 mm; 2 in. = 38 mm; 3 in. = 64 mm; 4 in. = 89 mm; 5 in. = 114 mm; 6 in. = 140 mm; 7 in. = 159 mm; 

8 in. = 184 mm; 9 in. = 210 mm; 10 in. = 235 mm; 12 in. = 286 mm.
Cradle-to-Gate Life-Cycle Assessment of Redwood Lumber in the United States

39

Table B2—Redwood lumber dimensions 

and their volume contributions in 2017

Nominal dimensionsa Contribution (%)

1 by 2 0.0481

1 by 4 0.1831

1 by 6 0.2671

1 by 8 0.0499

2 by 2 0.1045

2 by 3 0.1535

2 by 4 15.8846

2 by 6 38.6600

2 by 8 13.2711

2 by 10 0.9331

2 by 12 9.1201

3 by 4 0.0003

3 by 6 4.2728

3 by 8 8.2682

4 by 4 6.1805

4 by 6 0.9549

4 by 8 0.5789

4 by 10 0.0077

4 by 12 0.0666

6 by 6 0.6748

6 by 8 0.1090

6 by 10 0.0200

6 by 12 0.0927

8 by 8 0.0506

8 by 10 0.0004

10 by 10 0.0012

10 by 12 0.0001

12 by 12 0.0011

Others 0.0454

a

Nominal measurements for dimensional lumber can 

be converted to standard metric measurements of the 

following: 1 in. = 19 mm; 2 in. = 38 mm; 

3 in. = 64 mm; 4 in. = 89 mm; 6 in. = 140 mm; 

8 in. = 184 mm; 10 in. = 235 mm; 12 in. = 286 mm.