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The primary difference between the Minneapolis wood and steel house
is the use of materials for floors and walls. Both designs share
the same basement and roof elements. For the Atlanta structure,
the only major difference between the wood and concrete design is
in the exterior wall structure as both designs use concrete floors
and wood roofs. Making cross design comparisons at the wall and
floor section shows much more dramatic percentage differences than
for the buildings as a whole (last two columns of the table below)
since some parts of the structure share common materials, and the
construction process itself is energy intensive and not that much
different across the designs. In effect a substantial environmental
performance difference for nearly substitutable products may not
seem so great for a completed structure with many common components. The Forest Resource Module also produces estimates of tree biomass by component. These estimates are used to approximate the standing and removed carbon pool over time. Other environmental performance measures including indices of stand structure, diversity, and habitat and fragmentation will be developed in subsequent phases of the project using a landscape approach to forest management will be developed in subsequent phases of the project. Harvested volumes from the two forest resource regions are considered in the context of lumber manufacturing in the Pacific Northwest and Southeast regions. Here the research developed independent LCIs for the two regions. The two regional lumber manufacturing modules were developed to provide the environmental, energy and resource impact data associated with the manufacturing of softwood lumber. In the Northwest (Appendix B) a survey produced the data for sawing, drying and planing processes. A unit process approach produced detailed descriptions of activities and the resources used to produce specific outputs. For example, the sawing process involves log movement within the mill, sorting and storage, delivery to debarkers, and bucking to length. The logs are then debarked and sawn into rough lumber producing rough lumber, resulting in the CO-products pulp chips, bark and sawdust. The rough lumber is transported within the mill to stacks for kiln dryers or planer facilities. Maintenance work on equipment and vehicles are also recorded, as were emissions to air, water and land. The results of the survey work produced detailed information that was then analyzed with the SimaPro life cycle program. The SimaPro analysis considered four processes, including energy generation in addition to the three processes mentioned above. The result of the analysis produces unit factor estimates for one Mbf of planed dry lumber. These unit factor estimates include raw material use, airborne, waterborne, and solid emissions, and energy use. A similar module was used for Southeastern lumber production (Appendix C). Harvested volumes from the two forest resource regions were also considered in the context of softwood plywood manufacturing in the Pacific Northwest and Southeast regions (Appendix D). Surveys were implemented in a manner similar to those used in conjunction with the the lumber manufacturing modules. The plywood process was defined in terms of six processes: bucking and debarking, block conditioning, peeling and clipping, drying, lay-up and pressing, and trimming and sawing. The results of the survey work produced detailed information that was then analyzed with the SimaPro life cycle program to produce unit factor estimates for one Msf of 3/8-in basis of plywood. An LCI for Oriented Strand Board (OSB) production was produced in a similar manner (Appendix E); however for this interim report, the integrated residential construction analysis used plywood as the default for all panels because the material balances were not completed at the time that the integration analysis was performed. The survey also collected information on log transport, production of phenol-formaldehyde and MDI resins and wax. Data is now available to provide a comparison of energy and resource impacts relative to the 1976 CORRIM study. Data is also available to provide a measure of resource use efficiency. With the LCI data produced by the lumber, plywood and OSB modules, LCIs can be produced for derived products such as glulams, trusses, and laminated veneer lumber, all of which will be incorporated into the final report. Management and process improvements can also be identified and analyzed with key scenarios planned for the final report. An analysis of costs and carbon accounting have been initiated in Phase I and can now be completed in conjunction with a more thorough integration with resource harvesting, production, and the ultimate use, maintenance, and disposal phases of each product. With these additions and corrections, the final report will provide:
LIFE CYCLE ENVIRONMENTAL PREFORMANCE OF RENEWABLE MATERIALS IN THE CONTEXT OF RESIDENTIAL BUILDING CONSTRUCTION
January 27, 2002
1 Bowyer is director, Forest Products Management Development Institute, Department of Wood and Paper Science, University of Minnesota; Briggs is director, Stand Management Coop, Lippke is director, Rural Technology Initiative and Perez-Garcia is associate professor, College of Forest Resources, University of Washington; Wilson is professor, Department of Forest Products, Oregon State University.
LIST OF TABLES
1.0 INTRODUCTION
1.1 BACKGROUNDThe motivation for creating CORRIM to conduct this research is increasingly intense public interest and debate regarding environmental impacts and sustainability of building products manufacture and use, and particularly intense concerns with respect to forest management and the flows of products that originate from forests. Unfortunately, the environmental consequences of changes in forest management, product manufacturing, consumption, and disposal are poorly understood and there is a lack of current, scientifically sound life-cycle data in the United States for wood and other bio-based products. The last major research effort in the United States dealing with these issues for wood and bio-based products was completed in 1976 by CORRIM I, the Committee on Renewable Resources for Industrial Materials under the auspices of the National Research Council (1976). Though an extensive landmark study, information developed under CORRIM I is now both incomplete and out-of-date in the context of current issues and concerns. Recognizing the need for updated and more comprehensive information, CORRIM II (the Consortium for Research on Renewable Industrial Materials) was created to develop a scientific base of information relating to the environmental performance of wood building products and to examine factors that can affect the efficient use of energy and materials in manufacturing and use of building materials. These factors include forest management to increase carbon sequestration, improving the efficiency of manufacturing processes, reducing waste and potentially toxic materials, and sustain healthy forest ecosystems. The intent in creating CORRIM II was to develop:
Figure 1.1. Integrated Life-cycle of Biological Materials (CORRIM
1998)
Soon after the establishment of CORRIM II, a request for proposals
was issued by AF&PA in 1994 as part of its' Agenda 2020 program.
The Agenda 2020 program focuses on pre-competitive research needs
of the US forest products industry, and the '94 RFP targeted two
principal research objectives relative to environmental life cycle
inventory and analysis: (1) development of an updated analysis of
the environmental efficacy of renewable building materials, including
consideration of environmental impacts related to energy consumption
and (2) identification of alternatives for reducing environmental
releases associated with building materials through their life-cycles.
This led to funding of CORRIM II in 1996 by the U.S. Department
of Energy ($125,000) and the forest products industry ($54,000)
to develop a research plan. This plan, outlining research activity
within 22 modules over a 5-year span (Table 1.2) was released in
January 1998 (CORRIM 1998). In addition, protocols and standards
were described in the research plan to ensure that data collection
and analysis would be compatible with ISO life-cycle analysis guidelines
(ISO 1997, 1998, 2000a, 2000b) and LCI procedures developed for
the forest industry (AF&PA 1996). Table1.2: CORRIM Research Modules - (from CORRIM 1998) Phase I Research consists of Highlighted Areas (CORRIM 1998) All
estimated funding (monetary figures) are in $5 000's
Preceding the CORRIM II initiative was a project to develop current environmental performance information for building materials used in Canada. This project, titled "Building Materials in the Context of Sustainable Development", was initiated in 1990 as the ATHENA project by FORINTEK Canada Corp, and is now continuing at the ATHENA Sustainable Materials Institute. In 1997, an alliance was established between CORRIM and ATHENA to take advantage of previous ATHENA research and to broaden the geographic and product representation of research.
1.2 OBJECTIVES, MODULAR DESIGN, AND SCOPE OF CORRIM PHASE ISubsequent to development of the long-term, 22-module CORRIM research plan, funding was made available to conduct a first phase effort (modules 1-4, 7, and a portion of 12 as highlighted portions of Table 1.1), with the following two objectives:
The Phase I research effort was concentrated on development of life cycle inventory data for wood-based building materials produced in the two regions of the US that account for the greatest production of forest products - the Pacific Northwest and the Southeast. Further, because of funding limitations, the scope of Phase I was limited to consideration of the structural shells or envelopes of residential buildings. Although focused on wood-based materials, Phase I research did address environmental performance of wood-framed buildings in comparison to residential buildings constructed of steel and of concrete block. Data for these other materials was obtained from the Athena Sustainable Materials Institute.
1.3 ORGANIZATIONAL FRAMEWORK TO CONDUCT PHASE I RESEARCH
Figure 1.2. CORRIM Organization Chart (CORRIM 1998) Table 1.3: Lead Scientists Involved in CORRIM - Phase I Chair of Technical Steering Committee, Dr. Jim Bowyer, University of Minnesota
1.4 REPORT STRUCTURE
The objectives of this module are to: The objectives of this module are to: The objectives of this module are to: The objectives of this module are to: Objectives of this module are to: 2.0 LIFE CYCLE ANALYSIS FRAMEWORK
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Generic LCA Model
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CORRIM
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Comment
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| Forest Growth Time frame: 25-100+ years |
Nursery, planting, thinning, fertilizing, during
the growth cycle. Effects on carbon sequestration/global warming,
diversity, habitat, streamside conditions, etc. |
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| Raw Material Acquisition | Harvesting Time frame: < 1 year |
Logging during commercial thinning or final harvest. Effects on soil compaction and productivity, diversity, habitat, siltation, etc. |
| Manufacturing | Manufacturing Processes Time frame: < 1 year |
Individual products (lumber, plywood, LVL, OSB,
etc) Assemblies of products (trusses, glulam beams, I-joists, etc.) Air & water emissions, solid waste. |
| Construction of Structures Time frame: < 1 year |
On-site or factory built components (floor, wall,
roof) and finished structure. Solid waste. |
|
| Use/Reuse/Maintenance | Service Life & Use Time frame: 40-100+ years |
Maintenance cycles (painting, re-roofing, siding, etc.) and remodeling. Energy use & associated emissions/waste, energy & emissions associated with repair/remodel products. |
| Recycle/Waste Management | Recycling & Disposal Time frame: < 1 year |
Teardown, segregation of materials, recycle, combust for energy, landfill. Energy use & substitution, air & water emissions, solid waste/carbon sequestration. |
Figure 2.3. A Depiction of CORRIM Phase I Research
2.4.1 LCA Components
Table 2.1 and Figure 2.3 suggest that the LCA of a building system
is a composite of many separate, but interrelated, LCA'S. A building
system LCA is created through cumulatively embedding the LCAs of
many processes and their associated products, sub-assemblies and
assemblies, each containing a specific set of life cycle stages
from raw materials through recycling and waste management. For some
products, certain stages may become deferred and be dependent on
the aggregated LCA of the entire building of which they become a
part. Examples are wall studs and other main framing lumber products
that are covered by other materials and remain unchanged during
the building life; these items typically have no maintenance stage
of their own. Similarly, the recycling and disposal stage may only
apply to only some of the products when the building is finally
demolished (i.e. recycling and disposal of these individual products
is not separable from the building as a whole).
2.4.2 Initiation and Scope of Phase I
Construction of a complete residential home can be viewed as involving
three categories of component LCAs. The first of these includes
all of the products and assemblies required to produce the structural
skeleton of the building. The second category involves additional
products, such as siding, insulation, and roof topping, to complete
the building envelope. The third category involves products and
activities to complete the interior.
As noted earlier, the scope of Phase I CORRIM research is restricted
to a study of a subset of the overall system. This subset includes:
2.4.3.2 Product Manufacturing &
Unit Processes
An objective of Phase I is to treat each major step of each manufacturing
process as a separate unit ("unit process") for data collection.
For example, a sawmill can be viewed as consisting of the following
processing centers (or unit processes): log yard, debarking and
bucking, primary breakdown of logs into trimmed, green lumber; kiln
drying, planer mill, and grading and packaging. This level of detail
allows for recognition of various product grades and joint products
from each center that may be sold to other industries without further
processing. It also recognizes alternative pathways of primary material
through the mill (green lumber to grading & packaging versus
green lumber to kiln drying). By performing data collection at the
unit process level, many potential issues with respect to co-product
allocation can be resolved and differences among various technological
configurations for a unit process can be examined. Data for individual
unit processes and facilities will vary by plant age and type, and
factors such as transportation distances will also vary by region.
Sampling individual facilities and unit processes provides a sense
of the variation in the industry and permits summarization that
provides the range, median, mode and upper/lower quartiles. This
permits analyses that can focus on the sensitivity of outcomes to
advances in adoption of technology such as indicated by the rhetorical
question: "What happens as the industry gradually improves
so the average moves up to the current upper quartile?"
CORRIM Phase I involved gathering of current data through questionnaires
sent to selected individual manufacturers. Table 2.2 lists wood
products and assemblies for which CORRIM data has been collected
from manufacturers during Phase I.
| Softwood lumber, kiln dried (US Southeast, US Pacific Northwest) |
| Softwood lumber, green (US Southeast, US Pacific Northwest) |
| Softwood plywood (US Southeast, US Pacific Northwest) |
| Oriented strandboard (US Southeast) |
| Glue laminated beams |
| Laminated veneer lumber |
| Parallel strand lumber |
| Wood "I" joists & beams |
Construction of buildings also involves consumption of non-wood materials such as concrete for foundations and steel for nails and fasteners, etc. Life-cycle data for these materials and products were taken from previous life-cycle studies compiled or conducted by the Athena Sustainable Materials Institute. Table 2.3 lists products for which CORRIM is using data from previously published LCAs during Phase I.
Table 2.3: Products Considered
in CORRIM Using Data from Studies
Conducted by the Athena Sustainable Materials
Institute
Material |
Product Considered |
Concrete |
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Steel |
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2.4.3.3 Building Construction
Construction of a building involves a fundamental shift from individual
products to the combination of these into building assemblies (wall,
floor, and roof systems) using spans, loads, and other variables
that comply with building codes. The activities associated with
construction include those involved in producing building materials,
as well as new life-cycle steps and impacts tied to construction
activity in which materials and energy are consumed, and solid wastes
and emissions are produced. Some effects are simply the aggregate
of the various materials used in the construction assemblies while
others are unique to the construction activities and are not attributable
to an individual component product. To integrate various combinations
of products into functionally equivalent assemblies and competed
structures, CORRIM used the Environmental Design Model of ATHENA
(1997) which contains more than 50 different assemblies incorporating
combinations of concrete, steel, and wood products. Working with
ATHENA researchers, CORRIM developed additional structural
designs based on residential building codes in Minneapolis, MN and
Atlanta, GA to represent cold and warm climate conditions, respectively.
2.4.3.4 Building Use and Maintenance
Unlike siding, roofing and other assemblies required to fully complete
the exterior of a building, the structural materials and assemblies
generally require little direct maintenance during the operational
life of a building. Consequently, maintenance requirements are not
considered in CORRIM Phase I. Maintenance will be analyzed in detail
in later research in the context of a fully completed and occupied
building.
Energy consumption during the operational life of the building will
be estimated based on the average home in each city hence providing
perspective on the relative importance of this stage on overall
life-cycle energy consumption and emissions. Further research on
energy consumption during the operational life of buildings will
be conducted in the future.
2.4.3.5 Building Demolition and Material
Recycling or Disposal
Recycling and waste management focus on the individual materials
for which recycling and waste management opportunities differ greatly.
Energy and emissions are involved in demolition/deconstruction,
separation and transport of the materials, and in recycling and
waste management processes. Since a building may not be demolished
for many years after construction, accurate depiction of this stage
would require forecasting technologies and markets for recycling
and waste management far into the future. Since these conditions
are unknown, CORRIM assumes that current practices are applicable.
Furthermore, research suggests that demolition, recycling, and disposal
differences between alternative designs are small (FORINTEK &
Wayne B. Trusty 1997). Therefore, comparisons between design alternatives
will be reasonably accurate in the absence of good data for this
stage. However, when absolute effects of individual designs are
required, better data for this stage will be necessary, a topic
for future research.
Improvement analysis refers to using LCA results to suggest opportunities
for environmental improvement or to evaluate proposed changes to
a product, process, or design. Since improvement analysis often
involves different technical expertise (process design engineers,
product designers), and broader considerations (economic and market
factors) than information gained from a life-cycle study, it is
often conducted independently of LCA or as an adjunct to an LCA.
Through sensitivity and scenario analyses and studying material
substitutions, CORRIM research will provide comparisons and insights
that will assist analysts, designers, managers, and policy makers
in understanding relative benefits and costs associated with alternatives
and understanding which stages in the life-cycle provide the greatest
leverage for improvement.
Many life cycle inventories are performed for non-durable products
for which the time from resource extraction until post-consumer
disposal was so short that the temporal distribution of events and
associated impacts can be ignored. In contrast, the life cycle for
CORRIM research covers a very long time frame, beginning with planting
a forest stand, cultivating it to maturity, harvesting and converting
logs into products that are assembled into buildings, tracking the
activities during occupancy and use of the building until its eventual
demolition and disposal. For CORRIM, the time dimension becomes
great and presents difficulties that are not well discussed in the
LCA literature. Some activities, such as the growth of a forest
stand and associated carbon removals from the atmosphere and the
consumption of energy for heating and cooling of a building, occur
in relatively small annual quantities; the aggregate total when
trees are harvested or when a building is demolished would be misleading
since the totals and associated emissions did not occur in these
specific single event years. Other events such as fertilization
of the forest or re-roofing a building only occur at intervals so
a total, expressed as if these events occurred simultaneously does
not make sense. To properly deal with the timing of events and emissions
and avoid misleading aggregations, CORRIM developed a method for
portraying the life-cycle as a series of cohorts (forest stand and
building age classes) that move through time. Correct accounting
at any time point is the sum of the activities and emissions of
those cohorts that coexist at that time. To illustrate, consider
a simplified CORRIM life-cycle consisting of the following phases:
The series of conversion and building processes from "stump
to structure" completion that commonly takes 2 years or less
° young relatively little maintenance, replacement, or remodeling occurs during the early use of a new home.
° middle-aged: the first cycle of maintenance and replacement activities begins, hence there is demand for materials to accomplish them as well as disposal issues for the replaced materials.
° old-aged: maintenance and replacement cycles may intensify as the house becomes outdated and homeowners undertake various remodeling steps.
Figure 2.4 portrays the "cradle-to-grave" perspective
for the cohorts with the time-line shown underneath; "h"
is the age when the forest is harvested and "T" is the
time when the building is demolished. The problem with the timeline
perspective is that it creates some logic issues and violates the
tenet that LCI is based on empirical, not forecast data. At any
time chosen as the present, data for all activities beyond that
time point are forecast data that must rely on assumptions regarding
changes in technology and design. If the present is assumed to be
the time of planting seed, can we assume that today's building codes,
design practices, and materials will be relevant when the home is
built from these trees at h+2 years in the future? If not, what
will the relevant codes, designs, and materials be? If thinnings
are conducted, is it logical to pool them with the final harvest
as inputs into the "stump to structure" stage? In the
real world, no mill stores thinnings from a stand for 15 or 20 years
in order to process them with the logs from the final harvest of
that stand.
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........................Forest Growth........................
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........................Building Use........................ | ||||||||
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N
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0.......................................................h..................h+2......................................................................T
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Figure 2.4. The Timeline of the CORRIM Life-Cycle
To illustrate a different type of problem, consider the final disposal of the building. The disposal, materials recovered, and emissions to the environment of a new building that will not be built until far into the future, and which will not be torn down until much later, are likely to be very different than the problems associated with tearing down and disposing of materials from the today's obsolete buildings. A question to be raised is "are we really interested in the cumulative impacts associated with planting seeds in a nursery and, perhaps 200 years into the future, tearing down and disposing of a building made from them?
The difficulties with the timeline approach in Figure 2.4 can be
overcome by recognizing that all cohorts exist simultaneously in
a time period (Figure 2.5). Today, nurseries are producing seedlings
for planting on lands that were just harvested, there exists a mix
of forest age classes receiving silvicultural treatments (pruning,
thinning, fertilization), some are producing logs from thinnings
and some from final harvesting for manufacturing processes that
produce products, subassemblies and housing developed with known,
current technologies and design methods. Owners of relatively new
buildings are dealing with relatively minimal upkeep and repair;
owners of, say, 15-30 year old buildings, are involved in many maintenance
activities using current materials and code requirements; owners
of much older homes are dealing with the unique problems they present;
and some of the existing housing inventory is being demolished and
replaced. The environmental impacts of demolition of today's obsolete
homes reflect the actual materials of the past that were used to
build and maintain them. This includes problems such as lead-based
paints and asbestos that will not be used in future designs but
are impacting current disposal and recycling options and will continue
to have an impact in the near future.
Summation of activities performed on today's stocks of forest lands
and housing, coupled with today's processing, construction, and
demolition and disposal methods, provides a more realistic "bottom
line" inventory report on the current status of resource and
energy consumption and releases to the environment. Furthermore,
empirical data can be collected on each of these activities because
they are occurring now. Thus all data is empirical in the true spirit
of a life-cycle inventory. Similarly, it is relatively easy to collect
data on current costs of labor, capital, raw materials (both virgin
and recycled) and energy associated with each activity and on market
prices for products and develop benefit/cost information.
Figure 2.5. Simultaneous Cohorts in the CORRIM Life-Cycle System
Figure 2.5. Simultaneous Cohorts in the CORRIM Life-Cycle
System
If one wishes to study the effect of a policy change, such as lengthening
forest rotation cycles to store additional carbon, this can be easily
accommodated with the cohort approach. Implementing such a policy
would alter forest practices whereby each of today's age classes
in Figure 2.5 becomes the start of a process where that class evolves
over time in response to practices that would implement the policy
(Figure 2.6). Thus, the young stands that were just thinned and
fertilized in the present will evolve toward maturity over time
under the influence of this policy.
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| B/C0 | B/C1 | .... | .... | B/CT |
Large bold cells represent pathways (left to right) from present
age classes of forest lands and housing. Bold italic cells represent
pathways based on future plantings after stocks of existing forests
are harvested.
As the forest evolves, it yields logs from thinning and final harvest
at any point in time that are processed by industry into products,
subassemblies, and houses. The changes in forestry to accommodate
the policy may alter the quantity, size, and quality of the logs
available to industry thereby forcing changes in processes, products,
and designs which create new homes for occupancy. Concurrently,
maintenance, replacement, repair/remodel, and demolition/disposal
is continuing on older homes produced in previous periods. Thus
the effect of a policy produces changes in the forest which in turn
have lagged effects on the characteristics of materials which later
may affect technologies used, products, and design. By forecasting
these changes to a time of interest in the future and summing the
columns for the time periods, one can obtain inventory summaries
and summarize the costs, revenues, and other benefits that occur.
These "bottom line" summaries can then be compared in
terms of change in physical parameters of interest and in terms
of economics.
This approach, in which cradle-to-grave aspects of forest products
are regarded as simultaneously occurring cohorts, allows analysts
to develop a valid life-cycle-inventory status report on the current
situation, develop economic measures of the current situation, and
then use forecasting techniques and sensitivity analysis to estimate
how changes in any system element lead to changes in environmental
and economic measures over time.
This perspective provides a means for reconciling difficulties with
temporal aspects of life-cycle inventories associated with forestry
and housing and provides a means by which the tool of life-cycle
inventory can be used in conjunction with the tools of economic
analysis. It is also consistent with the approach commonly used
by individual firms in applying and combining life-cycle inventory
and improvement analysis methods in identifying cost-effective ways
to provide products with improved environmental performance.
The section describes the accomplishments achieved in Phase I in
summary form. A major accomplishment is the preliminary environmental
assessment for the construction of a single family building shell.
Other accomplishments include life cycle inventories for wood and
other processes that produce the materials and energy used to construct
the single-family shell. Detailed information on these processes
has not been available until now. Phase I also initiated research
into other processes that have yet to be addressed elsewhere including
cost analysis, carbon inventory measurements and dynamic issues
associated with forest resources.
One of Phase I's major realizations is the preliminary environmental
assessment for a building shell using two sets of different materials.
Five indices are constructed and used to summarize the many output
measures from the LCI on the building shell. The indices measure
embodied energy, greenhouse warming potential, air pollution, water
pollution and solid wastes. All measures, except one, indicate lower
values for the wood design in Atlanta and Minneapolis. The one exception
is in Minneapolis for solid waste, where the steel design produces
about one ton less solid waste than the wood design. One can infer
from the environmental assessment that the wood design results in
lower energy and pollution measures with the one exception noted
above. An examination of a change in forest management suggests
small but significant changes in the index measures. A near 10%
increase in the construction of wood design shells in Minneapolis
associated with a 5% increase in land productivity results in index
measure declines of 4% for the global warming index, 6% for the
embodied energy and air pollution indices, 25% reduction in the
water pollution index and a 1% increase in the solid waste index.
A 5% increase in land productivity leads to a 17.5% increase in
the construction of wood design shells in Atlanta and a reduction
in all output measures ranging from 3% for water pollution to 13%
for solid wastes.
To complete the environmental assessment Phase I produced several
LCIs. Life cycle inventories were produced for forest resources,
lumber manufacturing, plywood production, and oriented strand board
manufacturing.
The Forest Resource module provides the environmental, energy and
resource impact data on the growth, management, harvesting and reforestation
of timber for the Pacific Northwest (PNW) and Southeast regions
of the US for a representative acre within each region. The study
calculates volume harvested for three general combinations of management
intensity and site productivity for each region. The combinations
were reduced to a single estimate of yield using weighting factors
developed for this research. The weighting scheme creates a base
case for each region. Alternative weights, such as more acres under
a higher level of management intensity, produce an alternative case,
with a different calculated volume. For example, the increase in
merchantable volume under the alternative case was 21% in the Southeast
(including volume from the second rotation when rotation ages are
reduced) and 16% in the Pacific Northwest.
The portion of lumber and pulpwood produced in the Southeast changed
slightly under the alternative scenario; lumber output share declined
2.1 percentage points and pulpwood increased 2.1 percentage points.
The alternative scenario also leads to a 3.6 % decrease in the average
rotation age in the Southeast, which is responsible for the percentage
shifts in lumber and pulpwood produced. Lumber output increased
15% in the Southeast, only 68% of the total volume increase. Lumber
output share remained at 100% in the base and alternative PNW scenarios.
System costs increased by around one percentage point above the
percent change in the amount of merchantable volume removed in the
Southeast; however, the shorter rotation may more than offset that
increase in a discounted cash flow analysis. System costs increased
about the same percent as merchantable volume removed in the PNW.
A similar result is observed for fuel and lubricant consumption
during harvesting operations: an 11% increase in the Southeast and
16% increase in the PNW roughly corresponding to the changes in
merchantable volumes harvested, although there appears to be a slight
increase in the consumption factors in the Southeast due to the
change in rotation age and products harvested. The increase in harvested
volume resulted from using 4 times more nitrogen and phosphate in
the Southeast and 2 times mores nitrogen and phosphate in the PNW
as fertilizer inputs in conjunction with the other management changes.
Along with harvested volumes, the study also produces harvesting
cost data and air emission estimates related to stand growth and
harvesting. Resources used to produce the harvested volume, such
as fuel, fertilizer and herbicides, are quantified and their impacts
reported in the Environmental Impact Report during the extraction
phase of the single family shell construction.
The Forest Resource Module also produces estimates of tree biomass
by component. These estimates are used to approximate the standing
and removed carbon pool over time. Other environmental performance
measures including indices of stand structure, diversity, habitat
and fragmentation using a landscape approach to forest management
will be developed in subsequent phases of the project.
Harvested volumes from the two forest resource regions are passed
on to lumber manufacturers in the Pacific Northwest and Southeast
regions. Here the research developed independent LCIs for the two
regions. The two regional lumber manufacturing modules were developed
to provide the environmental, energy and resource impact data on
the manufacturing of softwood lumber. In the Northwest a survey
produced the data on sawing, drying and planing processes. The unit
process approach produces detailed descriptions of activities and
the resource used to produce specific outputs. For example, the
sawing process involves log movement within the mill, their sorting
and storage, their delivery to debarkers, and bucked to length.
The logs are then debarked and sawed into rough lumber producing
rough lumber, pulp chips, bark and sawdust. The rough lumber is
transported within the mill to stacks for kiln dryers or planer
facilities, two additional processes with their corresponding activities.
To accomplish the sawing activity maintenance work on equipment
and vehicles are also recorded, as well as treatment processes of
air, liquids and solid materials. The result of the survey work
produced detail information that was then analyzed with the SimaPro
life cycle program. The SimaPro analysis consisted of four processes,
adding energy generation to the three processes mentioned above.
The result of the analysis produces unit factor estimates for one
Mbf of planed dry lumber. These unit factor estimates include raw
material usage, airborne waterborne and solid emissions, and energy
usage.
The Southeastern lumber module produces similar type of data. The
survey responses were not detailed enough to break out the sawing
processes into three components, hence sawing was considered as
a single process. Therefore the SimaPro analysis consisted of only
two processes: lumber and energy generation.
Harvested volumes from the two forest resource regions are also
passed onto softwood plywood manufacturers in the Pacific Northwest
and Southeast regions. The research module for softwood plywood
production produces the life cycle inventory data used in the LCI
for the building shell. A survey was implemented in a manner similar
to the lumber manufacturing modules. The plywood process was defined
in terms of six processes: bucking and debarking, block conditioning,
peeling and clipping, drying, lay-up and pressing, and trimming
and sawing. The result of the survey work produced detail information
that was then analyzed with the SimaPro life cycle program. The
result of the analysis produces unit factor estimates for one Msf
of 3/8-in basis of plywood.
Phase I also produces an LCI for Oriented Strand Board (OSB) production.
Using a survey, Phase I collected information on log transport,
production of phenol-formaldehyde and MDI resins and wax. The environmental
and energy impact data were recorded and passed along to the construction
phase of the research.
Phase I provides data that will allow a comparison of energy and
resource impacts relative to the 1976 CORRIM study. Data is also
available to provide a measure of resource use efficiency. With
the data produced by the lumber, plywood and OSB modules, process
improvements can also be identified. An analysis of costs and carbon
accounting has been initiated in Phase I as well as a preliminary
integration of the various processes.
AF&PA. 1994. Agenda 2020: A Vision and Research Agenda for
America's Forest, Wood and
Paper Industry. American Forest and
Paper Association. Washington, D.C.
AF&PA. 1996. Life Cycle Inventory Analysis User's Guide: Enhanced
Methods and
Applications fort the Products of
the Forest Industry. American Forest and Paper
Association. Washington, DC
Andersson, K., and T. Ohlsson. 1999. Life Cycle Assessment of Bread
Produced on Different
Scales. Intl J. LCA. 4(1): 25-40.
ATHENA 1993a. Raw Material Balances, Energy Profiles and Environmental
Unit Factor
Estimates: Cement and Structural Concrete
Products. Prepared by Canada Center for Mineral
& Energy Technology and Radian
Canada, Inc. Athena Sustainable Materials Institute.
Ottawa, Canada.
ATHENA 1993b. Raw Material Balances, Energy Profiles and Environmental
Unit Factor
Estimates: Structural Steel Products.
Prepared by Stelco Technical Services, Ltd. Athena
Sustainable Materials Institute. Ottawa,
Canada.
ATHENA 1993c. Raw Material Balances, Energy Profiles and Environmental
Unit Factor
Estimates: Structural Wood Products.
Prepared by FORINTEK Canada Corp. Athena
Sustainable Materials Institute. Ottawa,
Canada.
ATHENA 1997a. The Summary Reports: Phase II and Phase III
and Research. Prepared by
FORINTEK Canada and Wayne B Trusty
& Associates. Ottawa, Canada.
ATHENA 1997b. Working with ATHENA: Comparative Manual
and Model Case Study
Assessments. Prepared by The Environmental
Research Group, School of Architecture,
University of British Columbia. Athena
Sustainable Materials Institute. Ottawa, Canada.
Curran, Mary Ann (Ed). 1996. Environmental Life Cycle Assessment.
McGraw-Hill, New York.
Canadian Standards Association, Z760-94 Life Cycle Assessment: Environmental
Technology
(1994), ISSN 0317-5669, Toronto.
CORRIM 1998. Environmental Performance Research Priorities: Wood
Products: Final Report
on the research plan to develop environmental
performance measures for renewable building
materials with alternatives for improved
performance. Consortium for Research on
Renewable Industrial Materials (CORRIM,
Inc.) DOE Agreement No. DE-FC07-96ID13427,
Subcontract 417346.
CORRIM 2001. Research Guidelines for Life Cycle Inventories (draft).
Consortium for Research
on Renewable Industrial Materials
(CORRIM, Inc.) Seattle, WA.
FORINTEK and Wayne B. Trusty, Ltd. 1997. The Summary Reports: Phase
II and Phase III and
Research Guidelines. FORINTEK and
Wayne B. Trusty & Associated, Ltd. Ottawa, Canada.
Franklin Associates, LTD 1990. Resource and Environmental Profile
Analysis of Polyethylene
and Unbleached Paper Grocery Sacks:
Final Report. Franklin Associates LTD. Prairie
Village, KS.
IFIAS, 1974, Energy Analysis Workshop on Methodology and Convention,
International
Federation of Institutes for Advanced
Study, Workshop Report No. 6, Stockholm.
ISO 1997. Environmental Management-Life Cycle Assessment-Principles
and Framework, ISO
14040. First Edition 1997-06-15, International
Standards Organization, Geneva.
ISO 1998. Environmental Management-Life Cycle Assessment-Goal and
Scope Definition and
inventory analysis, ISO 14041. First
Edition 1998-10-01, International Standards
Organization, Geneva.
ISO 2000a. Environmental Management-Life Cycle Assessment-Life Cycle
Impact Assessment,
ISO 14042. First Edition 2000-03-01,
International Standards Organization, Geneva.
ISO 2000b. Environmental Management-Life Cycle Assessment-Life Cycle
Interpretation, ISO
14043. First Edition 2000-03-01, International
Standards Organization, Geneva.
Mann, Margaret K., and P.L. Spath. 1997. Life Cycle Assessment of
a Biomass Gasification
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National Renewable Energy
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National Research Council 1976. Renewable Resources for Industrial
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267pp.
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The CORRIM Home Page is administered through the College of Forest Resources at the University of Washington. CORRIM is a research consortium formed to establish, support, and manage research and education programs relating to renewable industrial materials focused on the environmental impact of the production, use, and disposal of wood and other bio-based materials. The Consortium includes 13 US and Canadian Research Institution members and a number of contributing companies, associations and agencies. This Institution is an equal opportunity provider. For more information please email Bruce Lippke or write toCORRIM, University of Washington BOX 352100 Seattle, WA 98195, (206) 543-0827. |