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Wood products have many environmental advantages over nonwood alternatives. Documenting and publicizing these merits helps the future competitiveness of wood when climate change impacts are being considered. The manufacture of wood products requires less fossil fuel than nonwood alternative building materials such as concrete, metals, or plastics. By nature, wood is composed of carbon that is captured from the atmosphere during tree growth. These two effects—substitution and sequestration—are why the carbon impact of wood products is favorable. This article shows greenhouse gas emission savings for a range of wood products by comparing (1) net wood product carbon emissions from forest cradle–to–mill output gate minus carbon storage over product use life with (2) cradle-to-gate carbon emissions for substitute nonwood products. The study assumes sustainable forest management practices will be used for the duration of the time for the forest to regrow completely from when the wood was removed for product production during harvesting. The article describes how the carbon impact factors were developed for wood products such as framing lumber, flooring, moulding, and utility poles. Estimates of carbon emissions saved per unit of wood product used are based on the following: (1) gross carbon dioxide (CO 2) emissions from wood product production, (2) CO 2 from biofuels combusted and used for energy during manufacturing, (3) carbon stored in the final product, and (4) fossil CO 2 emissions from the production of nonwood alternatives. The results show notable carbon emissions savings when wood products are used in constructing buildings in place of nonwood alternatives. Evaluating the environmental impact of product
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The Carbon Impacts of Wood
Richard Bergman
Maureen Puettmann
Adam Taylor
Kenneth E. Skog
Wood products have many environmental advantages over nonwood alternatives. Documenting and publicizing these
merits helps the future competitiveness of wood when climate change impacts are being considered. The manufacture of
wood products requires less fossil fuel than nonwood alternative building materials such as concrete, metals, or plastics. By
nature, wood is composed of carbon that is captured from the atmosphere during tree growth. These two effects—substitution
and sequestration—are why the carbon impact of wood products is favorable. This article shows greenhouse gas emission
savings for a range of wood products by comparing (1) net wood product carbon emissions from forest cradle–to–mill output
gate minus carbon storage over product use life with (2) cradle-to-gate carbon emissions for substitute nonwood products.
The study assumes sustainable forest management practices will be used for the duration of the time for the forest to regrow
completely from when the wood was removed for product production during harvesting. The article describes how the carbon
impact factors were developed for wood products such as framing lumber, flooring, moulding, and utility poles. Estimates of
carbon emissions saved per unit of wood product used are based on the following: (1) gross carbon dioxide (CO
) emissions
from wood product production, (2) CO
from biofuels combusted and used for energy during manufacturing, (3) carbon
stored in the final product, and (4) fossil CO
emissions from the production of nonwood alternatives. The results show
notable carbon emissions savings when wood products are used in constructing buildings in place of nonwood alternatives.
Evaluating the environmental impact of product
choices is increasingly important to help address sustain-
ability issues. Wood products have many environmental
advantages over nonwood alternatives (Wegner et al. 2010,
Lippke et al. 2011, Ritter et al. 2011, Eriksson et al. 2012).
One advantage is a lower global warming impact, which
refers to the impact on climate change of product production
from emissions of greenhouse gases (GHGs) to the
atmosphere. Although there are many GHGs, carbon
dioxide (CO
) gas released from burning fossil fuels is the
main driver of global warming (Intergovernmental Panel on
Climate Change [IPCC] 2013). To provide some context on
the magnitude of the problem, we looked at global fossil
fuel CO
emissions. The US Energy Information Agency
(US EIA) reported that in 2011, global fossil fuel CO
emissions were about 35.9 billion tons,
an increase of 3.4
percent from 2010, with China contributing the most at 9.6
billion tons (US EIA 2014a). The increase in global carbon
emissions occurred even though the United States, the
second largest contributor at 6.1 billion tons, had lower
emissions in 2011 than 2010.
An area of huge concern is fossil fuel and cement
emissions because of their ties to building construction,
particularly in Southeast Asia (i.e., China), where fossil fuel
resources are consumed to build residential structures
(Wang et al. 2013). For example, although global fossil
fuel and cement emissions declined 1.4 percent in 2009
The authors are, respectively, Research Forest Products Technol-
ogist, USDA Forest Serv., Forest Products Lab., Madison, Wisconsin
( [corresponding author]); Owner, WoodLife
Environmental Consultants, LLC, Corvallis, Oregon (maureen.; Associate Professor and
Wood Products Extension Specialist, Tennessee Forest Products
Center, Univ. of Tennessee, Knoxville (; and
Supervisory Research Forester, USDA Forest Serv., Forest Products
Lab., Madison, Wisconsin ( This paper was
received for publication in May 2014. Article no. 14-00047.
ÓForest Products Society 2014.
Forest Prod. J. 64(7):000–000.
The present article was written with the wood building products
industry in mind. Therefore, English units will be used instead of
metric units.
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because of the financial fallout from the Great Recession,
this circumstance was quickly reversed with a substantial
gain of 5.9 percent in 2010, which also exceeded the world
2010 gross domestic product (GDP) gain of 5.0 percent, a
disturbing condition of increasing fossil carbon intensity per
GDP when considering present and future impacts to
climate change (Friedlingstein et al. 2010, Peters et al.
2012, British Petroleum [BP] 2014). Cement is an important
component of concrete, which competes directly with wood
in buildings.
Documenting the merits of wood will be important to the
future competitiveness of the forest industry when selection
of products will be made in part based on the climate change
impacts associated with their production and use. In the
United States, buildings consume roughly 40 percent of the
energy generated; this includes the ‘‘operating energy’’ of
buildings as well as the ‘‘embodied energy’’ (the energy
required for manufacturing) of the building products
produced (US Department of Energy [US DOE] 2012). To
ensure that buildings incorporate products with low
environmental impacts, it is important that information on
the net carbon emissions associated with production and use
be provided in a format that is clear, concise, and available
to a wide range of building product specifiers and users,
including architects, engineers, builders, and homeowners.
The environmental advantages of wood products are
important and may be common sense to many; however, not
everyone recognizes and understands these merits. Life-
cycle assessment (LCA) is the internationally accepted and
standardized method for evaluating the environmental
impacts of products. LCA is a scientific approach to
assessing the holistic environmental impacts of a product,
including the resources consumed and the emissions
released. An LCA can cover the life of a product from
extraction of raw materials to production (i.e., ‘‘cradle-to-
gate’’; Fig. 1), or from extraction through production to
distribution, use, and final disposal (i.e., from ‘‘cradle-to-
grave’’). LCA can identify unit processes of the manufac-
turing stage with higher environmental impact (‘‘hot
spots’’), and companies can use this information to improve
their product’s environmental footprint. For cradle-to-gate
manufacturing of wood products, the manufacturing stage
typically outweighs the energy consumption and carbon
emissions associated with the forest resource removal and
regeneration stage and raw material transportation stage by
at least a factor of 10 (Puettmann and Wilson 2005,
Puettmann et al. 2010). For our analysis, we estimate net
carbon emissions through product production and include
carbon stored during the useful life of a wood product. We
also include emissions from raw material transportation but
not transport and installation of wood products (or nonwood
substitutes) in end uses. This comparison implicitly assumes
that transport and installation emissions are similar for wood
products and nonwood substitutes.
Life-cycle assessment can be used to compare the
environmental impacts of products; consumers can use this
information to choose products with better environmental
footprints (e.g., lower net GHG emissions). Many cradle-to-
gate LCA studies have focused on wood products (www. and their nonwood alternatives. These
analyses generally indicate that the manufacturing stage
(rather than raw material extraction or transportation)
accounts for greater environmental emissions then any
stage of a wood products’ life cycle. LCAs have shown a
low emission environmental profile for wood compared with
nonwood products that can serve the same function.
Performing an LCA for a product is a detailed, data-
intensive process, and the results may be difficult to
Figure 1.—Generic cradle-to-gate product production flow diagram.
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interpret for nonexperts. Thus there is a need for simplified
metrics from LCA studies, especially to enable users and
specifiers of building products to choose materials with
favorable environmental footprints.
In the present study and the Consortium for Research on
Renewable Industrial Materials (CORRIM) research done
so far, a distinction is made between logging and mill
residues that are part of the sequestered carbon in the
standing tree. Logging residues including branches, bark,
and tops that are generated during harvesting, which make
up approximately 30 to 50 percent of the tree harvested, are
left behind in the forest to decay (Lippke et al. 2011,
Ganguly et al. 2014, Hyto
¨nen and Moilanen 2014).
However, Sathre and Gustavsson (2011) showed logging
residues can be collected and used as fuel to generate
electricity, thus replacing fossil-fuel based electricity, as
reported by Bergman et al. (2013b) in the case of redwood
logging in California. Most likely, though, logging residues
will not be collected unless part of a forest management plan
and thus will be left to decay in the forest, which is the
assumption made in the present article. Therefore, assuming
sustainable forest management practices will be followed
from the time the forest was harvested for wood until the
time the forest has completely regrown, the net carbon flux
of the forest for logging residues is zero. This could be a
conservative estimate because some of the carbon in the
logging residues may become part of the soil organic carbon
and be permanently sequestrated (Sathre and Gustavsson
2011, Skog et al. 2014). Concerning the impacts on soil
carbon from forest harvesting, we assumed no lasting effect
on soil carbon would occur during forest harvesting
(Johnson and Curtis 2001, Lippke et al. 2011, Pacaldo et
al. 2013), although there is some uncertainty around this
assumption (Garten 2002, Nave et al. 2010). As for mill
residues, the mill residues are a coproduct of the log brought
to the production facility. Because mill residues are
generated on-site, their use for energy or other purposes
such as feedstock for other products is practically 100
percent. Mill residues not used for energy are not considered
in calculating carbon impact factors for the same reason that
logging residues (for which sustainable forest management
practices will enable the forest to regrow to its original state
before the next harvest) are not considered, and thus no net
carbon flux from the forest for mill residues occurs. This
may be a conservative estimate as well because some carbon
from mill residues may be stored in various other wood
products for several decades.
Carbon footprint
The quantity of CO
and other GHGs released per unit of
product during a product’s manufacturing and, in some
cases, end use and disposal, is sometimes referred to as its
‘‘carbon footprint’’ (International Organization for Stan-
dardization [ISO] 2013). Coal, oil, natural gas, and wood all
contain solid carbon that becomes CO
gas when the
material is burned for energy. CO
, methane (CH
), nitrous
oxide (N
O), and water vapor are the primary GHGs of
concern. Increases in GHGs in the atmosphere are
considered the primary factor in global warming. Global
warming impact is measured for each GHG in tons of CO
equivalent (CO
eq), where 1 ton of CO
represents the global warming (radiative forcing (RF)) it
causes over a specific time period, typically 100 years.
Because of the need to conserve energy resources and
avoid GHG emissions, there is a global push to choose
materials that have a low carbon footprint. The carbon
footprint of a product can be calculated by measuring all the
direct and indirect energy and material inputs to the
manufacturing of a product and considering the carbon
emissions associated with these inputs. Therefore, a carbon
footprint can be determined through an LCA with the
analysis limited to emissions that have an effect on climate.
During the production of wood materials, energy is used
during harvesting to run equipment such as chainsaws and
skidders, to fuel the transportation of logs to mills, and
during manufacturing to power saws, planers, dryers, etc.
Depending on the source of energy, the released emissions
contribute to a variety of impact categories such as
acidification (e.g., sulfur emissions), eutrophication (nitro-
gen), smog (particulates), and global warming (CO
Although many gases (e.g., methane) contribute to global
warming and carbon footprint, CO
is by far the most
important GHG in wood product life cycles from forest
cradle–to–mill output gate (Puettmann and Wilson 2005,
Puettmann et al. 2010).
Fossil versus biogenic carbon emissions
The production of energy from combustion sources
results in CO
emissions. When coal, oil, natural gas, or
wood are burned, water vapor and CO
are the primary
atmospheric emissions. The resultant energy may be used
directly in the production process, as heat or steam for wood
dryers, or indirectly, as sources for electricity generation
that can be used to power electric saw motors. For fossil
fuels (coal, petroleum, and natural gas), the CO
are commonly classified as ‘‘fossil CO
.’’ This classification
is in contrast to ‘‘biogenic CO
,’’ which is emitted from the
burning of biomass, such as wood. In the case of wood
products, much of the process energy for manufacturing
facilities is provided from burning wood-processing (mill)
residues (Puettmann and Wilson 2005), thus primarily
emitting biogenic CO
In terms of the contribution of CO
to the greenhouse
effect and the impact to climate change, there is no
difference between the atmospheric chemistry and physics
of biogenic and fossil CO
. However, a distinction is
commonly made between biogenic and fossil energy sources
in life-cycle–based analyses because of the cycling of
biogenic CO
from the atmosphere into wood resources and
back to the atmosphere (i.e., natural carbon cycle) in
comparison with the one-way flow of fossil CO
to the
atmosphere. For attributional life-cycle analysis, which
assesses the flux of emissions in the year a product is
produced, biomass energy sources are considered to be
offset when currently growing trees absorb CO
from the
atmosphere as part of the photosynthesis process. Under an
assumption of sustainable forest management, forests are
sustained so annual carbon released does not exceed the
annual carbon absorbed for the indefinite future. Therefore,
the atmosphere does not see a net increase in CO
(Beauchemin and Tampier 2008, Fernholz et al. 2009,
Richter et al. 2009). Therefore, we use the attributional life-
cycle analysis framework with a focus on current year net
emissions as part of an assumed long-term forest carbon
balance to count net zero emissions from wood energy
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A number of alternate methods can be used to evaluate
the impact of biogenic carbon emissions. One way is to use
attributional life-cycle analysis but to estimate net emissions
over a specific period of years by explicitly tracking carbon
fluxes that include harvest and regrowth of the forest (i.e.,
temporal effects). A second method involves consequential
life-cycle analysis, where a case of harvest and regrowth is
compared with a case without harvest and continued forest
growth over a specific time horizon. Features of these
approaches can vary depending on the time frame of
analysis, the extent of geographic area evaluated, and other
factors. For each of these types of evaluation, the degree to
which biogenic emissions are offset within a certain time
frame can depend on many potential factors including (1)
the types of biomass (e.g., logging residue, roundwood, new
plantations, mill residue), (2) the age of forests at harvest,
(3) forest growth rates, and (4) the extent to which increased
wood prices lead landowners to hold or increase land in
forest or intensify management (Brander et al. 2009,
˜o and Levasseur 2011, Cherubini et al. 2011,
Bergman et al. 2012, Agostini et al. 2013, Guest et al.
2013, Helin et al. 2013). Regardless of the framework, forest
growth from sustainable forestry can offset biogenic
emissions over time. It could take a shorter time (a decade
or less), or a longer time (many decades), depending on the
wood source and circumstances. The extent of the offset can
also be influenced by the GHG metric that is used (global
warming potential (GWP) vs. time-zero equivalent (TIZE);
Salazar and Bergman 2013, Nepal and Skog 2014). For
instance, the method used to estimate the impact to climate
change for the delay of wood decay while in storage either
as a product or in a landfill can provide different results.
This happens because the TIZE approach quantifies the RF
effects as they occur from GHG emissions, while the more
common GHG metric, GWP, quantifies RF effects from the
time of analysis out to the end of the selected time horizon,
typically 100 years for the GHG regardless of when the
emission occurred. The end result is that the TIZE approach
better estimates the impact to climate change for temporary
carbon sequestration in products and wood decay than GWP
(Salazar and Bergman 2013). However, if the additional
variables listed above had been included in the analysis, this
would have increased the complexity, thus generating more
uncertainty. Consequentially, attributional life-cycle analy-
sis as is done in our analysis is best used because it is more
robust for estimating the emissions directly linked with the
life cycle of a product and for emissions accounting.
Carbon storage
Wood can store carbon in trees and long-term wood
products for long time periods. A typical new 2,062-ft
home could contain 13,500 pounds of lumber, 3,160 pounds
of plywood, 6,470 pounds of oriented strandboard (OSB),
and 892 pounds of laminated veneer lumber, totaling 24,000
pounds of wood at 12 percent moisture content (MC) or
21,000 pounds of wood at 0 percent MC (Meil et al. 2004,
Wood Products Council [WPC] 2009). On average, OD
wood contains about 50 percent carbon by weight.
Therefore a 2,062-ft
home could store 10,500 pounds of
carbon or sequester 38,500 pounds of CO
wood MC is 12 percent. This value does not include
nonstructural wood products, which may have a shorter
service life. Service life of structural wood products tends to
match the service life of the structure itself. Therefore,
assuming an expected median life of 80 years for a single-
family home (Skog 2008), its stored carbon may last from
two to three forest rotation cycles of intensely managed,
highly productive forests (O’Connor 2004, Smith et al.
2005). This article considers carbon stored with products
installed in a building but not emissions that occur after the
service life of products.
As mentioned previously, carbon in wood products may
continue to be stored after its service (i.e., use) life in a
building, or it may be emitted by burning or decay. Wood
products may end up in landfills where most of the wood
does not decompose, it may be recycled into new engineered
products, it may be burned for its energy values, or it may be
reused as is in new construction (Skog 2008, Bergman et al.
2013a). Specifically, for wood to be used in new
construction, Bergman et al. (2013a) show fossil CO
emitted for new framing lumber and new hardwood flooring
are about four times greater than for recovered softwood
framing lumber and recovered hardwood flooring. Addi-
tionally, end-of-life (i.e., after first product use) scenarios
for old wood products can result in large cumulative energy
savings and fossil CO
emission reductions when discarded
wood is used to displace coal or natural gas in producing
electric power. In fact, for the base case end-of-life scenario
developed by Bergman et al. (2013a), these energy savings
would offset 53 and 75 percent of biomass energy consumed
to make new softwood framing lumber and new hardwood
flooring, respectively.
Avoided emissions
For this analysis, the ‘‘avoided emissions’’ are the fossil
carbon dioxide emissions from production of a nonwood
product alternative that are avoided when a wood product is
used instead (Fig. 2). The CO
emissions are estimated for
the production of the in-use equivalent amounts of the two
products. In the present study, product substitution is
assumed to be one-to-one. We assume the two products
have the same service life. This means that durability and
the long-term functionality of the structural wood product
and its nonwood substitute was considered to be equal in the
analysis, an assumption consistent with the findings of
O’Connor (2004). However, the life expectancy of all
products used in buildings varies depending upon the quality
of construction and owner preferences.
This study first estimates net carbon emission footprint
values per unit of product for a number of US-produced
wood products and for their nonwood product alternatives.
We estimate the carbon footprint for each wood product by
using fluxes shown for the wood product system in Figure 3.
The carbon flux for each nonwood product alternative (Fig.
2) is simply based on fossil fuel emissions. Second, we
estimate the savings in emissions by use of each wood
product instead of its nonwood product alternative as the
difference between the two carbon footprint estimates. In
essence, the system boundary for the present study is set to
analyze empirical data provided from raw material extrac-
tion to production through the LCA method for all products
that could be considered a partial analysis. The reason is that
although we assume sustainable forestry will be practiced in
the future, an underlying assumption exists that any
Using molecular weights of CO
and carbon, 38,500 pounds of
¼10,500 pounds of carbon 344 kg of CO
/12 kg of carbon.
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Figure 2.—System boundary and carbon fluxes for nonwood product production (Net emissions ¼D).
Figure 3.—System boundary and carbon fluxes for wood product production and carbon storage in end-use [Net emissions ¼(AB)
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additional forest harvesting for product substitution would
result in no net loss of forest carbon based on today’s
forestland levels. However, this is an unlikely scenario if
product choices are made based on the current carbon
impacts presented in this article. Therefore, this additional
harvesting carbon impact will need to be analyzed and
quantified when additional wood product substitution occurs
and then included in carbon impact factors for wood
Product data sources and descriptions
We used the existing wood product life-cycle inventory
(LCI) data sets to determine the net carbon emission
footprint for a range of wood products from cradle-to-
gate (Table 1; Fig. 3). Many LCI data sets for wood
product manufacturing and nonwood alternatives are
publically available through Web-based sources including
the US LCI Database (National Renewable Energy
Laboratory [NREL] 2014). In the US LCI Database,
which was used in this analysis, carbon emissions for the
wood product LCI data are allocated by mass. Interna-
wood product production to obtain carbon emissions from
wood products and alternative materials (PRe
2014). As shown herein, much LCI data exist for US
wood and nonwood products, and the list of sources will
grow with continued interest in environmental issues and
LCA. Some wood products are specified by geographical
areas. For example, softwood lumber is typically
produced in four areas, the Southeast (SE), the North-
east/North Central (NE/NC), the Pacific Northwest, and
the Inland West.
Carbon content
To calculate carbon stored in various products, we
calculated the mass and biogenic carbon content of each
wood product and the nonwood substitute alternatives
(Table 2). Some of the nonwood materials (e.g., vinyl
flooring) contain carbon, but in those cases, the carbon is
from fossil (e.g., petroleum) sources. We do not consider
fossil carbon content, because unlike wood products, the
carbon transferred from fossil fuel to nonwood products is
not being replaced as wood carbon is by continuing forest
regrowth. As shown in Figure 3, forests are actively
reabsorbing carbon removed by harvest and which then is
transferred to wood products. In Figure 2, there is no
equivalent reabsorption of fossil carbon emissions by the
source of the fossil fuel. Birdsey (1992) provided the carbon
content values for the various wood products.
Difference between wood and nonwood
product carbon footprints (net carbon emission
The net carbon emission footprints for the wood product
and nonwood product, respectively, are
Wood product net carbon emissions footprint ¼ABC
(see Fig. 3)
Nonwood product net carbon emissions footprint ¼D
(see Fig. 2). The difference between the two carbon
footprints for the 11 wood products and corresponding
nonwood substitutes indicates the emissions savings from
use of a wood product rather than the nonwood alternative
and is calculated using this formula
A¼Gross carbon emissions during wood production ¼
(fossil CO
þbiogenic CO
). Cradle-to-gate product
manufacturing consumes various energy sources, and
almost all energy production results in CO
Energy sources used in wood manufacture include
sources such as natural gas, diesel, gasoline, and
electricity derived from fossil fuels that release fossil
when combusted. Biomass energy from burning
wood processing (mill) residues is a major fuel source
for energy that releases biogenic CO
, not fossil CO
when combusted. Gross carbon emissions are also a
reasonable proxy for energy consumption even though
Table 1.—Data sources used to develop the net carbon footprint for each wood product and its substitutes.
Wood product Notes Wood data source reference Substitution product Alternative data source reference
Hardwood lumber Northeast/North Central region Bergman and Bowe (2008) Polyvinyl chloride
(plastic) moulding
Mahalle and O’Connor (2009)
Southeast region Bergman and Bowe (2010b)
Softwood lumber Northeast/North Central region Bergman and Bowe (2010a) Steel stud Rowlett (2004); Studs
Unlimited, Inc. (2013)Southeast region Milota et al. (2004)
Hardwood flooring Solid strip flooring Hubbard and Bowe (2008) Vinyl flooring Potting and Blok (1995)
Engineered wood Bergman and Bowe (2011)
Doors Solid wood Knight et al. (2005) Steel door Knight et al. (2005)
Softwood decking ACQ-treated pine Bolin and Smith (2011a) Wood–plastic composite Bolin and Smith (2011a)
Siding Western red cedar Mahalle and O’Connor (2009) Vinyl siding Mahalle and O’Connor (2009)
Softwood pole Pentachlorophenol-treated wood Bolin and Smith (2011b) Concrete pole Bolin and Smith (2011b)
Southeast region Kline (2004) NA NA
Pacific Northwest region Wilson and Sakimoto (2004) NA NA
Southeast region Wilson and Sakimoto (2004) NA NA
I-joist Pacific Northwest region Wilson and Dancer (2005) Steel joist DiBernardo (2013);
SSMA (2013)Southeast region Wilson and Dancer (2005)
Hardwood railroad tie United States Bolin and Smith (2013) Concrete railroad tie Bolin and Smith (2013)
ACQ ¼alkaline copper quaternary; SSMA ¼Steel Stud Manufacturer’s Association.
No direct nonwood substitution products for oriented strandboard (OSB) or plywood were identified. NA ¼not applicable.
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no carbon emissions are associated with hydroelectric
and nuclear power emissions. This occurs because
coal and natural gas are the primary energy sources
for generating power in the United States (USEIA
B¼Carbon emissions from burning wood residues ¼
(biogenic CO
). Biogenic CO
is released when wood
is burned for energy. These biogenic carbon emis-
sions are also being reabsorbed in forests and thus are
deducted from the gross carbon emissions in this
analysis (see emission and forest sequestration fluxes
in Fig. 3).
C¼Carbon stored in the wood product. CO
from the atmosphere during photosynthesis is con-
verted to wood, bark, and other parts of the tree. On
average, wood contains about 50 percent elemental
carbon by dry weight of wood (Table 2). If the tree
decays or burns, this solid carbon in the wood is
released again to the atmosphere as CO
gas, and the
carbon cycle continues. As long as the wood is
‘‘locked-up’’ in a product, the carbon is ‘‘seques-
tered’’ as a solid and does not contribute to climate
warming through the atmospheric greenhouse effect.
The carbon transferred to storage in a wood product is
also being replaced by regrowth in a sustainably
managed forest. This regrowth is equal to or greater
than the amount of the carbon transfer to products and
can be used to offset wood product production
emissions for the period that the carbon remains
stored in the wood product (see Fig. 3). The carbon
stored in the product was calculated by multiplying
the carbon content of a given wood product by the dry
weight of the individual wood product (Table 2) and
converting to CO
equivalents (Eq. 2).
Carbon storage ¼CSi¼CCi3Wi33:67 ð2Þ
¼carbon storage for a unit of wood product i(lb/
¼carbon content for wood product i(% carbon/
¼weight of a unit of wood product i(lb), and
3.67 ¼ratio of the molecular weight of CO
to the
molecular weight of carbon.
D¼Alternate product emissions avoided ¼(Nonwood
product fossil CO
). When the fossil CO
associated with the manufacture of a nonwood
product are not generated, this is considered
‘‘avoided emissions’’ (Fig. 2).
E¼Net carbon savings ¼(ABCD). The net carbon
emissions savings obtained by use of each wood
product is the difference between the carbon footprint
for the wood product and for the nonwood products
alternative. A negative value for Ecan be interpreted
as a ‘‘carbon credit’’ or carbon savings, where using
the wood product in place of a nonwood alternative
results in a reduction in the net amount of CO
in the
Table 2.—Mass and carbon content of some US wood products and their substitutes.
Product Material Unit
Biogenic carbon
content (%)
Moulding Northeast/North Central hardwood lumber 1 bd ft (12 312 31 in.) 2.22 50
Southeast hardwood lumber 2.22 48
Polyvinyl chloride (plastic) 2.65 0
Stud Northeast/North Central softwood lumber One 2 34 stud 7.65 52
Southeast softwood lumber 9.54 53
5.92 0
Flooring Engineered hardwood 1 ft
1.28 52
Solid hardwood 2.55 50
Vinyl 0.52 0
Doors Solid wood
One door 55.0 50
84.0 0
Decking Alkaline copper quaternary–treated One deck board 18.2 53
Wood–plastic composite 36.8 27
Siding Western red cedar 100 ft
93.4 50
Vinyl 55.6 0
Utility pole Pentachlorophenol–treated wood One 45-ft pole 1,315 53
Concrete 4,000 0
Oriented strandboard (OSB) Southeast OSB One 4 38-ft sheet @ 3/8 in. 34.8 51
Plywood Southeast plywood One 4 38-ft sheet @ 3/8 in. 33.8 54
Pacific Northwest plywood 29.3 51
I-joist Southeast wood One 16-ft-long, 10-in.-deep joist 76.2 50
Pacific Northwest wood 95.5 50
Steel joist
57.2 0
Railroad tie US wood One 7 in. high 39 in. wide 38.5 ft long 139 48
US concrete 700 0
All comparisons are cradle-to-gate (production gate). Therefore, no product use or disposal was considered.
Mass is listed at 0 percent moisture content.
Galvanized steel processes were used for steel studs, steel doors, and steel I-joists.
Solid wood door used Northeast/North Central hardwood lumber as input.
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E/A ¼Net carbon emission savings per unit of gross wood
emissions ¼(Net carbon savings/gross carbon
emissions during wood production).
E/C ¼Net carbon emission savings per unit of carbon in
wood ¼(Net carbon savings/carbon contents of wood
Because wood product units are of varying mass, the
absolute values for carbon footprints can be difficult to
compare across products. Normalizing the net carbon
savings by dividing by gross carbon emissions or by the
carbon content of the wood can show the relative
importance of the substitution and biogenic carbon effects
for each product. Negative values for the emission savings
per unit of wood emissions indicate that the gross carbon
emissions are more than offset by the use of wood biofuel,
carbon sequestration in wood products, and avoided fossil
carbon emissions. The magnitude of these negative values
for the emissions savings per unit of carbon in the wood
product indicates how effective use of a unit of wood in the
product is in offsetting emissions compared with use of a
unit of wood in other products.
Results and Discussion
All of the wood products examined in this analysis
provide a net emission savings when used in place of the
selected nonwood alternative products (Table 3). The
columns in Table 3 are labeled with letters corresponding
to those in Equation 1. Using solid wood doors as an
The net carbon savings for a single wood door
¼724:5ðEÞkg CO2eq
For individual wood products, Column E(Table 3) shows
the two lowest net carbon footprints for utility poles and
solid wood doors (5,618 and 724.5 kg CO
respectively). This is because utility poles and solid wood
doors are the two of the three largest wood products by
mass. Wood studs, which are smaller in size, have a less
negative net carbon footprint individually, but far more are
used; thus, it doesn’t make much sense to compare the
carbon footprints of these different products. A more
important comparison is the carbon footprint of the wood
product with its nonwood alternative. As shown in Table 3,
almost all of these nonwood alternatives require more
energy for their manufacture, and the energy used is almost
entirely fossil fuels containing carbon that has been stored in
coal, oil, and natural gas for millions of years.
Normalizing the net emission savings to a unit of gross
emissions for making wood products or a unit of carbon in
the wood product helps when comparing various wood
products. For example, utility poles result in 5,618 lb CO
eq net emission savings per pole. However, its normalized
net emission savings per unit of gross emissions pole
production is 5.6, which is near the value of 6.2 for the
SE wood stud product. The normalized values per unit
carbon in the wood product (E/C) are also similar, 2.2 and
2.5, respectively. The normalized values per unit carbon
are consistent with the reported GHG displacement factor of
2.1 by Sathre and O’Connor (2009). For all 11 wood
products studied including panel products, the values for
normalized net carbon emissions per unit of gross emissions
(E/A) range from 1.0 to 7.6, with a mean of 4.38 6
1.99. One way to interpret this finding is that, on average,
the use of wood building products avoids the use of about
four times as much fossil fuel as the cradle-to-gate
manufacture of the wood product requires.
The most effective ways to use a unit of wood to offset
emissions is indicated by the normalized value of net
emission savings per unit of carbon in the wood product (E/
C). By this measure, wood use is most effective in use for
solid wood doors, railroad ties, and hardwood lumber,
Table 3.—Carbon emission savings from use of US wood products in place of nonwood product alternatives (pounds of CO
per unit
of product).
Product Units Notes
Gross carbon released during
wood product manufacturing
Biofuel used during wood
product manufacturing
Hardwood lumber 1 bd ft (12 312 31 in.) Northeast/North Central region 2.0 1.3
Southeast region 2.4 1.8
Softwood lumber One 2 34 stud Northeast/North Central region 4.0 2.6
Southeast region 5.5 4.2
Hardwood flooring 1 ft
Solid strip flooring 2.4 1.5
Engineered wood 2.2 1.1
Doors One door Solid wood 102.5 64.8
Decking One deck board ACQ-treated pine 11.5 3.7
Siding 100 ft
Western red cedar 83.1 13.2
Utility poles One 4-ft pole Pentachlorophenol-treated wood 1,002 950
OSB One 4 38-ft sheet @ 3/8 in. Southeast region 41.9 23.6
Plywood One 4 38-ft sheet @ 3/8 in. Pacific Northwest region 12.6 9.0
Southeast region 22.3 14.3
I-joist One 16-ft-long, 10-in.-deep joist Pacific Northwest region 50.3 41.7
Southeast region 72.8 50.5
Railroad ties One 7 in. high 39 in. wide
38.5 ft long
United States 113.6 6.6
ACQ ¼alkaline copper quaternary; OSB ¼oriented strandboard.
Woody biomass energy.
Negative values represent a carbon credit.
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followed by utility poles, softwood lumber, pine decking,
cedar siding, and hardwood flooring.
Not all wood products have large substitution effects. In
fact, solid wood flooring had a less energy-intensive
nonwood alternative in this analysis, although the assump-
tion that vinyl flooring provides a functional equivalent to
wood flooring is debatable because of aesthetic consider-
ations and the potentially short service life of vinyl. A better
alternative for wood flooring might be ceramic or stone tile,
but we are not aware of LCI data for these products. As such
data becomes available, this type of comparative carbon
emission analysis can be redone to more accurately reflect
substitution scenarios.
Not all the products studied here have simple one-to-one,
nonwood alternatives (i.e., plywood and OSB). Concrete
block walls can be substituted for wood-framed walls that
contain OSB or plywood; however, these walls also contain
other products such as studs and nails. This type of more
complicated substitution scenario was not attempted for this
analysis but can be modeled using tools such as the Athena
Impact Estimator for Buildings (AIE4B; Athena Sustainable
Materials Institute [ASMI] 2014). For a demonstration of
the AIE4B tool using cradle-to-gate manufacturing LCI
data, see Lippke et al. (2004). Without considering the
carbon stored in the wood and not differentiating between
biogenic and fossil CO
emissions, Lippke et al. (2004)
showed that building wood-framed structures in Minneap-
olis, Minnesota, and Atlanta, Georgia, instead of building
steel- and concrete-framed structures reduced GHG emis-
sions by 26 and 32 percent, respectively, reductions that
were tempered by the fact all structures analyzed had
common concrete foundations. Much larger differences
were found when analyses were confined to assemblies that
contained fewer or no common elements.
Carbon emission savings for some wood products vary by
region. For hardwood lumber, the net carbon emission
savings for the NE/NC region is slightly larger than for the
SE region, about 1.0 percent more, whereas for wood studs
for the NE/NC region, the net carbon emission savings is
smaller than for the SE region, about 13 percent less. There
are two reasons for higher net carbon emissions savings for
wood studs in the SE. First, although more gross carbon is
released in manufacturing of the SE wood stud (5.5 vs. 4.0),
a greater amount of the gross carbon emissions come from
woody biomass (4.2 vs. 2.6); thus, fossil CO
emissions per
board foot are lower (5.5 4.2 ¼1.3 vs. 4.0 2.6 ¼1.4).
Second, the species composition for SE wood studs
(southern pines) has a substantially higher density than
species composition for the NE/NC wood stud, as noted in
Column Cin Table 3 (18.5 vs. 14.6; Milota et al. 2004,
Bergman and Bowe 2010a). Denser wood contains more
water than lighter wood at the MC. Therefore, denser wood
requires more drying to reach the same final MC starting
from the same initial MC as indicated by higher gross
carbon emissions for the SE than the NE/NC studs
(Bergman 2010). These density differences are not found
in hardwood lumber, which is primarily produced in the
eastern United States (Bergman and Bowe 2008, 2010b).
The reduced carbon emission impacts associated with
woody biofuel use and storage of carbon in long-lived wood
products result in lower net carbon emissions of wood
products compared with nonwood product alternatives. For
the cases we evaluated, the combined GHG emissions
reductions due to biofuel usage, carbon storage, and avoided
fossil emissions are always greater than the wood product
manufacturing carbon emissions. Thus, use of wood
products can help to reduce contributions to GHGs in the
atmosphere that increase the greenhouse effect, with the
caveat that sustainable forestry continues to occur from
product substitution. However, more wood product substi-
tution in the future would cause large removals of wood
during forest harvesting and could violate our assumption of
sustainable forestry. Therefore, this impact would increase
the carbon emissions associated with wood products and
thus lessen the effect of substitution.
For some wood products, such as wood flooring, the
nonwood substitutes are not quite equivalent because the
nonwood product is likely to have a substantially shorter use
Table 3.—Extended.
Carbon stored in
the wood product
Carbon released during nonwood
product manufacturing
Net carbon emission
Carbon emission savings per unit
of gross wood emissions
Carbon emission savings per
unit of CO
eq of wood
4.0 6.5 9.9 5.0 2.5
4.0 6.5 9.8 4.0 2.5
14.6 16.7 30.0 7.6 2.1
18.5 16.7 34.0 6.2 1.8
4.6 0.8 4.7 1.9 1.0
2.4 0.8 2.1 1.0 0.9
221.4 540.8 724.5 7.1 3.3
35.5 34.2 62.1 5.4 1.7
171.3 116.0 217.3 2.6 1.3
2,559 3,112 5,618 5.6 2.2
76.5 — 58.1 1.4 0.8
56.2 — 52.8 4.2 0.9
68.1 — 60.2 2.7 0.9
140.9 154.8 286.9 5.7 2.0
176.4 154.8 309.1 4.2 1.8
244.8 487.3 625.0 5.5 2.6
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life. Structural products such as softwood (framing) lumber
and their nonwood substitutes tend to have the same useful
life of the structure, and LCI data are available for both of
these products. The estimated net carbon emission savings
for these secondary wood products would likely be even
larger, e.g., if we used LCI data for more comparable
nonwood flooring products.
Net carbon emission savings for wood products can differ
among regions because of differences in species composi-
tion, and thus density, which influences the amount of
drying energy and carbon emissions. However, these
differences result in minor differences in net carbon
emissions savings.
Our estimates of net carbon emission savings use an
attributional, current period accounting framework to
estimate the emission benefits associated with wood energy
carbon emissions and wood product carbon storage. If we
used an attributional or a consequential dynamic time
framework, the level of carbon emission benefits of wood
energy use and wood product carbon storage would have
been lower but with higher uncertainty. Regardless of the
framework used, these carbon emission benefits would still
offset gross wood product manufacturing emissions. In
addition, using wood products avoids using known energy-
intensive producers of GHGs.
The work upon which this publication is based was
funded in whole or in part through grant no. 10-DG-
11420004-087 awarded by the Wood Education and
Resource Center, Northeastern Area State and Private
Forestry, US Forest Service.
In accordance with federal law and US Department of
Agriculture policy, this institution is prohibited from
discriminating on the basis of race, color, national origin,
sex, age or disability. To file a complaint of discrimination,
write USDA Director, Office of Civil Rights, Room 326-W,
Whitten Building, 1400 Independence Avenue SW, Wash-
ington, DC 20250-9410 or call 202-720-5964 (voice and
TDD). USDA is an equal opportunity provider and
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... 13 Just like most wood products, the high contribution from electricity used was the major contributor to the resulting impacts. 32,33,36 The environmental impact resulting from the raw material supply stage was not significant as compared with new pallet manufacturing. 19 This was mainly from the low amounts of virgin (new) lumber consumed during the manufacturing stage. ...
Wood pallets are ubiquitous products that can be recovered and reused to enhance their service life and environmental performance. Repair/remanufacturing has an important role in extending the service life of the wood pallet. To quantify environmental performances of wood pallet reuse, this study developed a representative life cycle inventory data of pallet repair/remanufacturing in the United States based on 2018 comprehensive industry‐wide production data. A gate‐to‐gate life cycle assessment covering raw material supply, raw material transportation, and pallet repair/remanufacturing showed that repair/remanufacturing often had the highest impacts including primary energy consumption at 5.09 MJ and global warming impact at 0.355 kg CO2eq per repaired/remanufactured pallet. Electricity consumed onsite followed by nail input and the fuel used by forklifts during the manufacturing drove much of the impacts on the environment. The results of this study provide valuable information on the repair/remanufacturing impacts allowing quantification and evaluation of the recovery stage on the overall environmental performance of wood pallets.
... Sustainably managed forests and forest products have a well-documented potential to deliver significant climate change mitigation benefits via sequestration, storage, and substitution (the 3Ss) when sourced sustainably and substituted for traditional resourceintensive materials [1][2][3][4]. Moving beyond product-specific considerations, a climate-smart forest economy (CSFE) aims to bolster the 3Ss and catalyze broader systemic change to address the climate crisis by leveraging forests and wood products. CSFE interventions may include any type of initiative, policy, or investment aiming to support a CSFE along various scales and configurations of forest management, development, planning, and construction, among other points of leverage. ...
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Sustainably managed forests and forest products have a well-documented potential to deliver significant climate change mitigation benefits via sequestration, storage, and substitution (the 3Ss) when they are sourced sustainably and substituted for traditional resource-intensive materials. Moving beyond product-specific considerations, a climate-smart forest economy (CSFE) aims to bolster the 3Ss and catalyze broader systemic change to address the climate crisis. In their most successful cases, forest value chain interventions that lead to CSFEs will link secondary and tertiary sectors for greater waste reduction, substitution, innovation, and overall cascading climate benefits. However, interventions that contribute to CSFEs, from small to large scale, will inevitably impact environments and communities, both directly and indirectly. While positive impacts can be thought of as co-benefits and should be encouraged, negative impacts are considered negative externalities, and these should be avoided or minimized wherever possible by safeguarding against harm. The failure to minimize negative externalities will have implications for equity, project longevity, and climate benefits. This paper provides preliminary results of mixed methods research with an aim of identifying and building consensus on the definitions, challenges, and solutions relevant to the assessment, planning, and implementation of CSFE safeguards. While broad and novel CSFE safeguards application faces diverse challenges, this paper explores practical solutions to advance and set a foundation for future dialogue, analysis, and application.
... From a life cycle IJSHE perspective, wood-based products have lower environmental impacts than other building materials thanks to their carbon storage potential and the renewability of the resource. In addition to substituting carbon-intensive, non-renewable materials, increasing the use of wood-based products in the building sector can contribute to climate change mitigation and help reduce resource depletion (Bergman et al., 2014;Buchanan and Levine, 1999;Gustavsson et al., 2006;Leskinen et al., 2018;Sathre and O'Connor, 2010). Whilst substituting non-wood materials appears to be a more effective approach than substituting fossil fuels (Geng et al., 2017), the carbon benefits of wood substitution also depend on forest management practices, as suggested by the studies of Peñaloza et al. (2016) and Pittau et al. (2018). ...
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Purpose Doctoral candidates possess specialized knowledge that could support sustainability transitions. Doctoral education, however, often focusses on discipline-specific topics and working methods, making it difficult to “see the bigger picture”. This summer school on wood construction gathered doctoral candidates from different fields to explore how solutions to complex sustainability issues could be found by working together across disciplines and by engaging multiple stakeholders. The purpose of this study is to report the pedagogical approaches taken and to understand whether these fostered the candidates’ ability to develop systemic solutions and professional competency. Design/methodology/approach Twenty doctoral candidates from various backgrounds participated in a two-week summer school organized by a consortium of four universities. Interdisciplinary groups worked on real-life challenges using a systemic approach to co-create tangible solutions. To support the creation of socio-technical innovations, stakeholders and experts from different fields were involved. The participants completed two questionnaires during the summer school to help elucidate their learning experiences. Findings The doctoral candidates showed strong willingness to cooperate across disciplines, though they found it important to connect this learning experience to their research. The candidates reported that the experience enhanced their ability to work in a multidisciplinary capacity. The experience identified a solid basis for interdisciplinary learning principles that could be replicated. Originality/value The summer school focussed on an innovative learning experience based on a systems thinking approach and the development of interdisciplinary capacity in the research-business ecosystem.
... In this context, wooden structures are considered lower carbon structures and represent lower embodied energy consumption compared to non-wood structures [42][43][44][45][46][47]. In addition, buildings using concrete and steel structural systems embody and consume 20% and 12% more energy, respectively, compared to buildings with wooden structures, so structural material selection plays an essential role in the amount of embodied carbon [48]. ...
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One of the most effective ways to cover real estate development and renovation processes by improving functionality and energy efficiency is wooden additional floor construction. This entry maps out, organizes, and collates scattered information on the current state of the art and the benefits of this practice including its different stages, focusing on the case of Finland. The entry presents this topic in an accessible and understandable discourse for non-technical readers. By highlighting the benefits and opportunities of this sustainable application, the entry will contribute to increasing the awareness of wooden additional floor construction, which has many advantages, and therefore to gain more widespread use in Finland and other countries.
•Uniquely important aspects of the boreal forest carbon budget relative to other regions include: smaller human populations with less direct anthropogenic influences and management, extensive areas of slow-growing coniferous forests, large areas of peatland and wetland complexes, substantial amounts of carbon stored below-ground in the region’s soils, and the presence of permafrost in many of these soils. •Boreal forest carbon budget accounting and reporting relies heavily on the national forest inventory programs of the major countries in the region, with other modeling approaches used to fill in the gaps in undersampled geographies and component pools. •Both top-down, atmospheric inversion modeling and bottom-up, terrestrial biosphere modeling have been challenged by a paucity of available data over the large extent of the mostly remote forest lands of the boreal region. •Uncertainties are being addressed—and confidence in budget assessments is improving—as new methods and expanded data collections are coming online, particularly with remote sensing. •How the land base is defined and reported as “managed forest” in boreal nations (that have large areas of noninventoried forest) will have important, global-scale implications for policy actions to mitigate GHG emissions.
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One of the challenges in research by modern engineers is the acquisition of new materials for the creation of various constructions in order to improve their properties, including mechanical ones. One possible way to achieve this goal is through composite materials. Moreover, the use of such materials in various real constructions leads to material, cost, energy and environmental savings, e.g. by reducing the weight of the products, significant reductions in fuel consumption, exhaust emissions and costs during transport can be achieved. Therefore, composite materials are of great practical importance, as seen in various applications in the automotive and aerospace industries, building construction and many other fields. Composite materials are inhomogeneous materials consisting of at least two various materials of different properties. Considering the construction of the composites, one can distinguish some typical examples, e.g., fibrous composites, when one component of the composite is made of fibers and the other is called a matrix. Another kinds of composite materials are sandwich or layered plates, in which their components are arranged in layers. Both of them have a wide range of applications in various engineering fields. On the other hand, there are multiple methods for analyzing the mechanical properties of these composites, including experimental, analytical or numerical studies. Corrugated cardboard, commonly used in the packaging industry, is a special type of corrugated material. In the case of corrugated cardboard boxes, the key is to obtain a durable and stable structure with a relatively low weight. Another important issue is the modeling of structures made of composite or corrugated materials. Their specific design and heterogeneity make it very expensive to build a complete model while maintaining all the details and is thus also very time-consuming. Therefore, both the material of individual components (layers) and the cross-sectional geometry are usually a priori homogenized to simplify and speed up the calculations. The simplification should not, however, distort the results that would be obtained using the full model. Therefore, the selection of an appropriate homogenization method is often a key issue when analyzing structures made of corrugated or composite materials. This Special Issue is devoted to the mechanics of composite materials, particularly corrugated materials, e.g., corrugated cardboard or multilayer boards with a soft core. In addition, the articles published in this Special Issue of Materials present different approaches to the research and application of various computational methods and the homogenization of selected composite materials. Finally, we take this opportunity to express our most profound appreciation to the MDPI Book staff; the editorial team of Materials, especially Ms. Daisy Liu, the managing editor of this Special Issue; all of the authors; and all of the professional reviewers. Tomasz Garbowski, Tomasz Gajewski, and Jakub Krzysztof Grabski Editors
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TÓM TẮT Using Sentinel 2 data on Google Earth Engine cloud computing platform for assesssing forest cover change in special use and protection forests in Vo Nhai district, Thai Nguyen province Changing in forest cover leads to a reduction of forest area in a spcecific time period. The research applied Google Earth Engine (GEE) to develop forest cover map layers and acccuracy assessment of classified forest cover maps for Sentinel 2. The study was conducted in special use forest areas in Specieal use and Protection Forest Management Board of Thai Nguyen province (former was Than Sa - Phuong Hoang nature reserve Management Board). Random Forest (RF) was applied in this study for classification and it performed a high acccuracy of classified images for forest covers. The results showed that the classification accuracy of classified maps in 2017, 2018, 2019, 2020 and 2021 was 98.7%; 99.3%; 99.3%; 98.5% và 99.5% (Overall acccuracy) and 0.974; 0.985; 0.986; 0.969 và 0.990 (Kappa) respectively. There was a significant upward trend of forest cover in the period from 2017 to 2021. Specifically, forested areas rose by 894,5 ha in the period from 2017 to 2021. The drivers of forest cover increase were due to afforestation and forest restoration. Implication of GEE, Sentinel 2 and classification algorithm RF achieved a high accuracy of the forest cover classification and it could be able to apply for other regions in Thai Nguyen province.
Near-zero energy buildings are known to have the potential to reduce energy consumption and consequent emissions. This article uses a life cycle analysis approach to evaluate the effects of using different insulating materials on the lifetime energy consumption of a near zero conditioning energy case study house in Wellington, New Zealand, by assessing the environmental impacts of a number of insulation options. The question addressed is whether using thick layers of insulation with high R-values in a building envelope is always a reliable approach to mitigating the impact of the built environment on the planet. The results show no significant difference between the environmental impacts of insulating the house using polyurethane and using no insulation in the first 28 years. The further discussion shows the energy profile used for processing the materials, construction and operating the buildings are not always the same, and this has a significant impact on the building’s environmental footprint. There needs to be a balance between both the value and profile of building operating and embodied energy. HIGHLIGHTS
Near-zero energy buildings are known to have the potential to reduce energy consumption and consequent emissions. This article uses a life cycle analysis approach to evaluate the effects of using different insulating materials on the lifetime energy consumption of a near zero conditioning energy case study house in Wellington, New Zealand, by assessing the environmental impacts of a number of insulation options. The question addressed is whether using thick layers of insulation with high R-values in a building envelope is always a reliable approach to mitigating the impact of the built environment on the planet. The results show no significant difference between the environmental impacts of insulating the house using polyurethane and using no insulation in the first 28 years. The further discussion shows the energy profile used for processing the materials, construction and operating the buildings are not always the same, and this has a significant impact on the building’s environmental footprint. There needs to be a balance between both the value and profile of building operating and embodied energy. HIGHLIGHTS
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This study compares the cradle-to-gate total energy and major emissions for the extraction of raw materials, production, and transportation of the common wood building materials from the CORRIM 2004 reports. A life-cycle inventory produced the raw materials, including fuel resources and emission to air, water, and land for glued-laminated timbers, kiln-dried and green softwood lumber, laminated veneer lumber, softwood plywood, and oriented strandboard. Major findings from these comparisons were that the production of wood products, by the nature of the industry, uses a third of their energy consumption from renewable resources and the remainder from fossil-based, non-renewable resources when the system boundaries consider forest regeneration and harvesting, wood products and resin production, and transportation life-cycle stages. When the system boundaries are reduced to a gate-to-gate (manufacturing life-cycle stage) model for the wood products, the biomass component of the manufacturing energy increases to nearly 50% for most products and as high as 78% for lumber production from the Southeast. The manufacturing life-cycle stage consumed the most energy over all the products when resin is considered part of the production process. Extraction of log resources and transportation of raw materials for production had the least environmental impact.
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In the living tree, wood contains large quantities of water. As green wood dries, most of the water is removed. The moisture remaining in the wood tends to come to equilibrium with the relative humidity of the surrounding air. Correct drying, handling, and storage of wood will minimize moisture content changes that might occur after drying when the wood is in service. If moisture content is controlled within reasonable limits by such methods, major problems from dimensional changes can usually be avoided. The discussion in this chapter is concerned with moisture content determination, recommended moisture content values, drying methods, methods of calculating dimensional changes, design factors affecting such changes in structures, and moisture content control during transit, storage, and construction. Data on green moisture content, fiber saturation point, shrinkage, and equilibrium moisture content are given with information on other physical properties in Chapter 4. Wood in service is always undergoing slight changes in moisture content. These changes that result from daily humidity changes are often small and usually of no consequence. Changes that occur because of seasonal variation, although gradual, tend to be of more concern. Protective coatings can retard dimensional changes in wood but do not prevent them. In general, no significant dimensional changes will occur if wood is fabricated or installed at a moisture content corresponding to the average atmospheric conditions to which it will be exposed. When incompletely dried material is used in construction, some minor dimensional changes can be tolerated if the proper design is used.
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Creosote-treated wooden railroad crossties have been used for more than a century to support steel rails and to transfer load from the rails to the underlying ballast while keeping the rails at the correct gauge. As transportation engineers look for improved service life and environmental performance in railway systems, alternatives to the creosote-treated wooden crosstie are being considered. This paper compares the cradle-to-grave environmental life cycle assessment (LCA) results of creosote-treated wooden railroad crossties with the primary alternative products: concrete and plastic composite (P/C) crossties. This LCA includes a life cycle inventory (LCI) to catalogue the input and output data from crosstie manufacture, service life, and disposition, and a life cycle impact assessment (LCIA) to evaluate greenhouse gas (GHG) emissions, fossil fuel and water use, and emissions with the potential to cause acidification, smog, ecotoxic-ity, and eutrophication. Comparisons of the products are made at a functional unit of 1.61 kilometers (1.0 mile) of railroad track per year. This LCA finds that the manufacture, use, and disposition of creosote-treated wooden railroad crossties offers lower fossil fuel and water use and lesser environmental impacts than competing products manufactured of concrete and P/C.
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This review on research on life cycle carbon accounting examines the complexities in accounting for carbon emissions given the many different ways that wood is used. Recent objectives to increase the use of renewable fuels have raised policy questions, with respect to the sustainability of managing our forests as well as the impacts of how best to use wood from our forests. There has been general support for the benefits of sustainably managing forests for carbon mitigation as expressed by the Intergovernmental Panel on Climate Change in 2007. However, there are many integrated carbon pools involved, which have led to conflicting implications for best practices and policy. In particular, sustainable management of forests for products produces substantially different impacts than a focus on a single stand or on specific carbon pools with each contributing to different policy implications. In this article, we review many recent research findings on carbon impacts across all stages of processing from cradle-to-grave, based on life cycle accounting, which is necessary to understand the carbon interactions across many different carbon pools. The focus is on where findings are robust and where uncertainties may be large enough to question key assumptions that impact carbon in the forest and its many uses. Many opportunities for reducing carbon emissions are identified along with unintended consequences of proposed policies.
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American Softwoods Japan Offi ce The Wood Use Points Program (WUPP) is a program initiated by the Forestry Agency (FA) in Japan to provide a subsidy of as much as ¥600,000 equivalent points when a home owner uses more than 50% of a "local wood" species for structural components and/or uses certain amounts of "local wood" species for non-structural interi-or or exterior decorations. All of the "local wood" species initially included in the WUPP were Japanese domestic timber species, including sugi, hinoki and Japanese larch. On December 17th, the U.S. Douglas-fi r timber spe-cies was approved as a new "local wood" species by the National Land Afforestation Promotion Organiza-tion (NLAPO), to the Corporation to Establish the Fund for the WUPP program. Consequently, US Douglas-fi r lumber and plywood for interior and exterior decorative end-use applications will be considered as "local wood" within the Wood Use Points Program following the of-fi cial announcement by the Head Offi ce of WUPP that U.S. Douglas-fi r has been approved. However, before U.S. Douglas-fi r lumber can be used in structural applica-tions, applications must be submitted to all 47 prefectures requesting that they add US Douglas-fi r as a "local wood" species for each construction method (e.g., post and beam and 2x4) that is included in the Wood Use Points program in each prefecture. At this point, initial indications are that the prefectural approval process will be completed sometime in March 2014. The application materials to designate US Douglas-fi r as a "local wood" species within the WUPP were prepared by Dr. Ivan Eastin (Professor and Director of the Uni-versity of Washington's Center for International Trade in Forest Products, CINTRAFOR) and Dr. Daisuke Sasatani (Auburn University). The American Softwoods Japan Offi ce submitted the application to the NLAPO. The third committee meeting was held on December 17th, and the application was approved by the committee members. Many Japanese and foreign companies/organizations have applied for the "local wood" designation and this was the third committee meeting to review the foreign applications since the WUPP program was launched. US Douglas-fi r was the fi rst, and only, foreign wood species to be approved as a "local wood" species under WUPP. "Local wood" species must satisfy two conditions in or-der to be included within the WUPP: 1) the resource inventory of the timber species must be increasing in the country where it grows and 2) the consumption of the "local wood" species must have a signifi cant economic ripple effect within Japanese rural agricul-ture, forestry and fi sheries communities. The offi cial forest resource inventory data compiled by the US Forest Service showed that the volume of Douglas-fi r growing in US forests has increased about 30% over the last 35 years. Thus the US Douglas-fi r timber re-source in the U.S. was shown to satisfy the fi rst con-dition of the WUPP. Regarding the second condition, there are a number of Douglas-fi r sawmills in Japan, with industrial clusters existing in the Setouchi and Northern Kanto areas. The U.S. application docu-ment explains how the processing of US Douglas-fi r contributes to the local economy where the major Japanese Douglas-fi r sawmills are located, thereby satisfying the second condition of the WUPP. Not only do the Douglas-fi r sawmills in Japan provide economic benefi ts within the local communities but the related industries, including distributors, second-ary manufacturers, ports, and markets for by-products also provide economic benefi ts within these local communities. Thus, it can be seen that the Douglas-fi r forest resource is well managed in the US and provides substantial economic benefi ts in rural agriculture, forestry and fi shing communities within Japan. In Japan, Douglas-fi r has a long tradition of being used as structural lumber, non-structural lumber, plywood, fl ooring, and other types of building materials. Japa-nese builders and carpenters especially favor using Douglas-fi r lumber in horizontal structural applica-tions in traditional post and beam homes, including as beams, girders and purlins because of the high strength of Douglas-fi r. Douglas-fi r is also favored because of its dimensional stability, durability and stable supply. Now that U.S. Douglas-fi r has been approved as a new "local wood" species it is expected that more houses will be eligible for the Wood Use Points Pro-gram and that many more home builders and home owners in Japan can now receive subsidies under the WUPP. The American Softwoods Japan Offi ce would like to encourage Japanese builders and architects to use more U.S. Douglas-fi r wood products and remind them that, at this time, the "local wood" species des-ignation for Douglas-fi r wood products has only been granted for Douglas-fi r timber harvested in the U.S.. If you have any questions, please contact Tomoko Igarashi at American Softwoods Japan Offi ce.
Conference Paper
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In LCA, an implicit or explicit carbon dioxide “credit” is typi­cally granted to bio-based resources that photosynthesize carbon as part of their natural growth cycle. An implicit credit is granted by ignoring the biogenic carbon emissions in the calculation of global warming potential (GWP). An ex­plicit credit is granted by accounting forest growth as a negative carbon dioxide emission and then tracking that sequestered carbon. Several widely used carbon footprinting standards (6,7) and product category rules (2,4,5) permit crediting based on explicit of end-of-life emissions and key to the methodology for doing so is the decision of how to include the temporal dimension of carbon emissions. Two recent methodologies have been developed to account for carbon sequestration in LCA that both apply a 100-year LCI cut-off but differ in the GWP characterization. The first method estimates GWP by modeling all emissions from end-of-life processes and then characterizing these flows by IPCC GWP (100-yr) factors (3). Another method estimates GWP by characterizing annual emissions with the IPCC GHG forcing functions (w/m2/yr), integrated over the same 100 year time horizon, and then relating the warming to the equivalent time-zero equivalent (TIZE) CO2 emission (1). The carbon sequestration results were calculated using both methods for 400 oven dry kg of wood (roughly 1 m3) over service lives of 25, 50, and 75 years. The results using TIZE were -464, -557,-669 kg CO2eq for 25, 50, and 75 years respectively. The results using GWP 100 were -416, -462, and -552 kg CO2eq for 25, 50 and 75 years. The TIZE method showed less overall warming impact in terms of kg CO2 time-zero equivalents relative to kg CO2eq (GWP 100). The spread between the two results is directly related to service life, with longer service lives exhibiting greater variation between results. The comparison exemplifies the need to harmonize carbon sequestration accounting methodology – particularly the temporal aspects.
Technical Report
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Within the green building fields is a growing movement to recover and reuse building materials in lieu of demolition and land fill disposal. However, they lack life-cycle data to help quantify environmental impacts. This study quantifies the primary energy and greenhouse gas (GHG) emissions released from the production of wood recovered from an old house and from new wood harvested from the forest and produced in a sawmill with both products ending up installed in a new house. In addition, the study quantifies the primary energy and GHG emissions released if the recovered wood is not reused but instead is either burned to replace coal or natural gas to generate electricity, landfilled with or without landfill gas capture equipment, ground into mulch, or some combination.
Technical Report
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The goal of the study was to conduct a life-cycle inventory (LCI) of California redwood (Sequoia sempervirens) decking that would quantify the critical environmental impacts of decking from cradle to grave. Using that LCI data, a life-cycle assessment (LCA) was produced for redwood decking. The results were used to compare the environmental footprint of redwood decking to other decking materials that serve an equivalent function. The other materials examined include plastic (cellular PVC) and wood–plastic composites (WPCs) with recycled content varying from 0% and 100%.
Conference Paper
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Static life cycle assessment does not fully describe the carbon footprint of construction wood because of carbon changes in the forest and product pools over time. This study developed a dynamic greenhouse gas (GHG) inventory approach using US Forest Service and life-cycle data to estimate GHG emissions on construction wood for two different end-of-life scenarios. Biogenic and fossil GHG emissions sources included a growing forest, logging slash, softwood lumber manufacturing, residue decay and combustion, and product in the landfill. The two scenarios focused on 1) disposing of old wood and logging forests for new construction wood and 2) reusing the old construction wood instead of making new and landfilling the old wood. GHG emissions covered a 100-year time-period and were allocated to 1.0 m3 of softwood lumber produced for two different forests and harvesting rates. Reusing old construction wood had lower GHG emissions initially. However, using new wood would eventually have lower GHG emissions because logged forests regrow and absorb carbon faster and for a longer time than unlogged forests. The paper shows the critical time delay in forest carbon re-accumulating from logging forests may be problematic in mitigating climate change in the short-term but unlikely in the long-term.