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Comparative Life Cycle Carbon Footprint of a Non-Residential Steel and Wooden

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DOI: 10.29011/2638-0013.100028

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 Current Trends in Forest Research
Laurent AB. Curr Trends Forest Res: CTFR-128.
Research Article DOI: 10.29011/ 2638-0013. 100028

Comparative Life Cycle Carbon Footprint of a

Non-Residential Steel and Wooden Building Structures
Achille-B. Laurent 1*, Yvonne van der Meer1, Claude Villeneuve2
1
Aachen-Maastricht Institute for Biobased Materials, Department of Biobased Materials, Faculty of Science and Engineering, Maas-
tricht University, the Netherlands
2
Chaire en éco-conseil, Département des sciences fondamentales, Université du Québec à Chicoutimi, QC, Canada
Corresponding author: Achille-B. Laurent, Department of Biobased Materials, Post-Doctoral Researcher on Bio-based Products
Sustainability, Maastricht University, Brightlands Chemelot Campus, Geleen, the Netherlands. Tel: +31-433882240; Email: achille.
laurent@maastrichtuniversity.nl
Citation: Laurent AB, van der Meer Y and Villeneuve C (2018) Comparative Life Cycle Carbon Footprint of a Non-Residential
Steel and Wooden Building Structures. Curr Trends Forest Res: CTFR-128. DOI: 10.29011/ 2638-0013. 100028
Received Date: 20 November, 2018; Accepted Date: 30 November, 2018; Published Date: 11 December, 2018

Abstract
In the field of construction, wood products are known to have environmental benefits in comparison with materials like
steel and concrete, especially to mitigate climate change. Since wood is an anisotropic material, comparisons with other build-
ing materials on a volume functional unit basis, such as a cubic meter of product, are not relevant. Wood structures also allow
for architectural forms that are not feasible with other building materials. To enable a comparison between wood and steel, we
have assessed the Life Cycle Carbon Footprint of complete non-residential building structures. This building frame was initially
planned to be made from steel, but the architecture was modified to integrate glued laminated timber beams. The structural en-
gineers provided material balance changes. The results show a significant reduction in greenhouse gas emissions for structures
using wood as a building material.

Keywords: Carbon Footprint; Life-Cycle Assessment; Non- Butler building (1906) in Minneapolis, MN or 320 Summer Street
Residential Buildings; Wood Buildings Material (1906) Boston, MA). It resulted in a lack of knowledge about
the potential of wood and engineered wood products, as well as
Introduction many misperceptions associated with the technical characteristics
of these structures. Thus, the expertise gradually vanished in the
In North America, wood components have always been
building sector.
ubiquitous in the structure of residential buildings. Today, this
wood culture is maintained and renewed by the marketing of The development of new elements of wooden structures,
components or prefabricated wooden frame houses. The situation is also called engineered wood, like glued laminated timber (glulam)
different in the nonresidential building sector, such as institutional, or more recently Cross-Lam Timber (CLT), have revitalized the
commercial or industrial buildings. In the past decade, less than 4% wood building market. These building systems make it possible for
of non-residential buildings in North America were made of wood wood products to become economically competitive. Nowadays,
[1]. In lasts years this has increased to 10% but for FP Innovations the costs of wooden structures are similar or lower compared to
there is potential for at least a twofold increase in the use of wood steel or concrete structures [3]. Another advantage is the speed of
for nonresidential buildings [2]. erection. As the elements are pre-built in the factory, it remains
only to assemble the different pieces of structure on site, hence
Several circumstances explain the low wood use in
accelerating the time of construction [3].
nonresidential construction in North America. Between the 1930s
and the 1970s, modern architecture reinvented the design of Among the presumed advantages of wood construction, it
public and commercial buildings, by utilizing the properties of is recognized that, in comparison with competing materials, the
concrete and steel structures [3]. This architectural revolution has low carbon emissions of the production line and the sequestration
gradually led to the erosion of wood structures in non-residential of CO2 in the material during the whole life-span of the building
buildings [1]. Indeed, from the beginning of the 20th century may be integrated into a climate change mitigation strategy [4].
only a few massive buildings were made from heavy timber (e.g. To compare the environmental impacts of competitive building

1 Volume 2018; Issue 04

Curr Trends Forest Res, an open access journal
ISSN: 2638-0013
Citation: Laurent AB, van der Meer Y and Villeneuve C (2018) Comparative Life Cycle Carbon Footprint of a Non-Residential Steel and Wooden Building Structures.
Curr Trends Forest Res: CTFR-128. DOI: 10.29011/ 2638-0013. 100028

materials, Life Cycle Assessment (LCA) is commonly used [5]. Definitions of The Objectives and Scope of the
The functional unit used in LCA usually is a surface area of System
building [5] or volume or weight of materials [6]. An easy method
to calculate carbon sequestration per cubic meter of wood products Objectives and scope definition are the first step of the
in a building is the use of the “displacement factor” [6]. This factor presented LCA, according to the ISO 14040 series standards [9].
is an index to quantify the reduction of Greenhouse Gas (GHG) It allows a more elaborate approach than a carbon footprint based
emissions obtained per unit of wood products substituted for non- on the standard ISO 14067 [10], as the latter makes possible to
wood products. A displacement factor of 2.1 tC/tC (metric tons calculate carbon footprint only related to the direct emissions, also
of carbon emission reduction per tC of additional wood products referred to as scope [11]. The boundaries of this study include all
used) was calculated by reviewing 66 studies around the world. direct emissions, indirect emissions from energy and other indirect
However, other parameters such as type of building, external emissions, also called scope 3.
climate, or architectural aesthetic design can also affect the carbon Application Envisaged and Target Audience
footprint and this is not taken into account in the displacement
factor. Additionally, assessing mechanical properties of building This study aims to assess the carbon footprint of using
materials is complex and makes comparisons by physical unit wood components instead of steel components in a nonresidential
(mass/volume) not appropriate, since nonequivalent functions construction. It provides decision makers quantified arguments of
are then assessed. Mechanical resistance is different if there is the steel substitution by wood to reduce greenhouse gas emissions
compressive (column) or bending (beam) strength for the materials and thus mitigate climate change. The study will take advantage of
[7] and this affects the sizing (section) of the structural components. a life cycle approach that avoids shifting environmental impacts
Comparisons on a physical unit base are even more difficult, or from one stage to another stage. However, this study does apply
not possible, for other architectural elements like arches, since not to a region-specific context. The glulam is modelled from primary
every building material can achieve such structure. data from the producer in Quebec, and the steel manufacturing is
representative for the North America market context. The model of
This study presents a detailed comparative assessment of
the construction stage is even specific for the building, since it was
GHG emissions and carbon sequestration in a life-cycle approach of
made from the data collected on the construction site.
a hybrid structure (made from wood and steel) and full steel frame
for a non-residential building. The aim is to calculate the carbon The results of the comparative study are relevant for a wider
emissions reduction that can be achieved with the use of wood audience interested in the use of wood in building structures to
material as a replacement for steel in a non-residential building. reduce climate change impacts.
The comparative scenarios were prepared for the same building
and were considered as building options for an arena located at the Functions and Functional Unit
Université du Québec à Chicoutimi (UQAC) campus (Saguenay, The main function of the studied system is to support the
Quebec, Canada). It was actually decided to choose to build the envelope of the UQAC arena during the lifetime of the building. The
hybrid structure, which is presently fully functional and for few structure of the building has multifunctional characteristics. Only
decades. This assessment has the particularity of using context- the primary function as support in the building was considered. The
specific primary data. Indeed, the structural engineering company secondary functions of this structure, like aesthetics and acoustic
that sized the steel and hybrid structures provided the calculated quality, are not considered. Since aesthetics depend mostly on
mass balance for the design of the two structures. The calculation architects and is a subjective criterion and acoustic aspects are
of wood impacts used a cradle-to-gate LCA of glulam company not a priority for a sports venue. The functional unit for this study
supplying arena beams [8]. These data were supplemented by field is: “The structure of a non-residential building (an arena more
data collected during the construction of the arena. precisely), covering an area of 3780 m2 (or a volume of 23,000
The Life Cycle Carbon Footprint (LCCFA) study is m3), for a life-span of 75 years”.
performed in accordance to the ISO 14044 LCA guidelines [9]. Since this is an existing structure, the functional unit
Therefore, the first section is devoted to the definition of the includes the area and volume of the building, which provides the
objectives and scope of the study. It is followed by the inventory opportunity to report the results to a physical allocation, in order to
analysis describing the sources and methodology used in the data calculate the displacement factor.
collection. In the third section, the impact assessment presents the
results of GHG emissions calculated from data inventories of both Reference Flow
building structures. Then the interpretation presents the analysis The reference flow represents the quantity of products
of uncertainty and sensitivity as well as additional elements of necessary to fulfill the functional unit.
discussion, all to draw conclusions in the final section.

2 Volume 2018; Issue 04

Curr Trends Forest Res, an open access journal

ISSN: 2638-0013
Citation: Laurent AB, van der Meer Y and Villeneuve C (2018) Comparative Life Cycle Carbon Footprint of a Non-Residential Steel and Wooden Building Structures.
Curr Trends Forest Res: CTFR-128. DOI: 10.29011/ 2638-0013. 100028

The lifetime of buildings in North America is not well at the processing and manufacturing sites of the two construction
documented. Only one study from the Athena Institute was materials studied. Data for extraction and production of the vari-
performed on 227 demolished buildings, of which 94 were ous steel elements (hollow structural steel, flange sections, as well
nonresidential. The results highlight the lack of correlation between as screws and bolts) are retrieved from the USLCI database (Na-
the materials used in a structure and the average life-span of the tional Renewable Energy Laboratory, Golden, Colorado) as these
building [12]. Demolitions reasons recorded were economic or are representative for average North American steel. The inventory
social but less than one-third was demolished for physical failure. includes a steel recycling rate of 76% [13]. The data for wood beam
Those cases were mainly related to fire damage and touched more production are taken from the cradle to gate LCA study of Quebec
steel than wood structures. The Athena Institute study showed a boreal forest glulam [8]. This inventory is provided from the fac-
longer lifetime expectation for wood nonresidential buildings, in tory that produced the glulam beams for the arena. It is important
comparison to steel or concrete. The majority of wood buildings to note that both steel and wood structures are preassembled at the
reached 75 to 100 years but there are buildings that pass the 100 factory. This includes other materials (e.g. glues for the glulam
years regardless of the building materials. A conservative point beams), energy and infrastructures dedicated to these transforma-
of view was taken in the study in which it was assumed that the tions or productions.
use of wood material in a nonresidential construction does not
require additional replacement or maintenance compared to a steel Once construction materials are ready to be assembled, they
construction. The reference flows for both types of structures were are transported to the construction site. Transportation of materials
considered identical for an expected life span of 75 years. Both is done by truck, from Toronto (ON) for steel and Chibougamau
models include the quantity of materials needed to support the (QC) for glulam. The model includes an allocation of trucks and
envelope. road infrastructures to this activity.
Since the wood structures are pre-assembled, the building
Product Systems and System Boundaries
activity consists of assembling the beams together. The construction
The boundaries are defined by the limits and the phases machines and the energy consumed are modeled. The data are
considered for the modeling of the system. The comparative primary data taken on site during the construction of the hybrid
carbon footprint covers the entire life cycles of the two building structure. The deconstruction activity inventory is modelled as
frames, thus a cradle-to-grave assessment. However, since it is identical to the building activity, as further explained in section
a comparative assessment, we chose to exclude the use phase general assumptions.
assumed to be equivalent, as further explained in the section
The end-of-life activity integrates the impacts of landfilling
general assumptions (Figure 1) shows the boundaries of the studied
and building materials recycling, including transportation and
systems.
infrastructures. The end-of-life scenario is based on the most recent
statistical data representative of the construction sector in the
Saguenay-Lac-Saint-Jean (QC) area. Since it is difficult to know
what will happen in 75 years, during the estimated deconstruction
of the building, a sensitivity study on this scenario is carried out in
the results section to estimate the influence of this scenario on the
total carbon footprint. Non-landfilled wood, 2% according to [14],
is modeled as a source of energy production.
Geographical Limits
The geographical boundaries of the study need to include
the origin of all resources. The study also needs to properly
model activities that are different from region to region, such
as transportation, energy generation (electricity grid) and waste
management systems. Moreover, the sensitivity of the environment
Figure 1: System boundaries of the study to different emissions varies from one geographic zone to
another.
Activities Description: The resource extraction mainly covers the
mining of iron ore resources and the harvesting of wood resources. To take account of these geographical aspects, the databases
Resources are then transferred to the transformation/production used must be adapted as much as possible. This study focuses
activity, which brings together the various stages that take place on the harvesting, processing, production, distribution, and end-

3 Volume 2018; Issue 04

Curr Trends Forest Res, an open access journal

ISSN: 2638-0013
Citation: Laurent AB, van der Meer Y and Villeneuve C (2018) Comparative Life Cycle Carbon Footprint of a Non-Residential Steel and Wooden Building Structures.
Curr Trends Forest Res: CTFR-128. DOI: 10.29011/ 2638-0013. 100028

of-life management in Quebec of a structure whose components equivalent, both are removed from the study. In fact, this
originate mainly from North America. Until 2007 Quebec’s crude assumption can be considered conservative and favorable
oil supply came mainly from the North Sea and North Africa [15]. to the steel structure, since the steel framing in the wall
To stick as much as possible to the local context an adjustment reduces the insulating resistance (R-value), and this is usually
was made based on the ecoinvent database (ecoinvent Centre, St- compensated by design techniques [21].
Gallen, Switzerland) inventories in Simapro software V7.3 (PRé • The amount of concrete required for the construction of
Consultants, Amersfoort, The Netherlands). foundations does not differ from a steel or a wooden structure
Time Limits [22]. The amount of concrete for the foundation is more
dependent on the soil and the possibility of earthquakes [22].
The time period defined by the functional unit corresponds to Therefore, concrete was not included in this study as it is the
the useful life expectancy of the building, that is 75 years. Since the same for the two studies in this comparison.
reference flow is the same for the two types of structures studied,
• The lifetime of the arena is similar, regardless of the structural
the temporal boundaries are defined for the estimated lifetime of
material chosen. The fatigue resistance of the two materials
the building. It is important to note that:
in question is most likely exceeding the lifetime of the
• Some processes can generate emissions over a long period. building, as discussed in the Forintek report [23]. Biogenic
Landfilled organic material, such as wood, may emit carbon sequestration is not considered, but is estimated in the
different GHGs over a very long period, depending on the discussion section. For all practical purposes in a dynamic
decomposition conditions. Some of these GHGs may or may analysis the estimated lifespan of a non-residential building in
not be transformed by flaring. North America can be estimated at 75 years [24].
• The construction of the arena took place in 2009 so we chose • A few studies mention that deconstruction is more labor
this year as a reference. This static LCCF is representative for intensive than demolition [25]. The deconstruction phase is
the year 2009. Any major change in one of the processes may not well documented in North America [26]. Therefore, we
change the results for other reference years. took the assumption of the deconstruction phase to be identical
to the construction phase. The model reuses equipment and
The Life Cycle Impact Assessment (LCIA) should cycles times of the construction phase.
theoretically be considered over an infinite period of time to take
into account the full extent of the effects and persistence of these • The modeling of different machineries (skidders, cranes, etc.)
events. In practice, we use models adapted to the substances used in all life cycle processes is not directly integrated into
analyzed, thus reducing the uncertainties. Since this analysis the ecoinvent database. We therefore resorted to a generic
focuses on GHGs, the potential effects of emissions can be model “diesel burn in building machine” from ecoinvent.
quantified for periods of 20, 100 or 500 years. In this study, we Inventory Data of the Carbon Footprint
use the impact method “IPCC 2007 GWP 100a [16] based on [17].
This time period is mandated by the ISO standard (ISO 14044) and This section provides an overview of the sources of the data
is the most suitable for the lifetime of the building of 75 years. It that were used, as well as an analysis of their quality.
is also the time horizon for the global warming potential of GHG Data Sources
in main international conventions (UNFCCC, Kyoto Protocol,
Primary data were mainly collected from the producer of
Western Climate Initiative), as well as in the most recognized
glulam beams used in the arena structure. The collection of these
carbon footprint quantification tools such as PAS 2050 [18] and
data was carried out during different visits to the producer with
the GHG Protocol for Product Accounting and Reporting [19];
support of those responsible for the various stages of harvesting and
other temporal considerations are not itemized [20].
processing as well as accounting data. The construction phase was
General Assumptions the subject of particular attention, with precise monitoring of the
assembly and fuel consumption. Missing, incomplete or not easily
This section presents general assumptions regarding the accessible data have been supplemented by the most representative
carbon footprint assessment, as well as the characteristics and assumptions and secondary data available in the cited literature
parameters of the materials of structures studied. or databases (ecoinvent and USLCI). We used ecoinvent and
• The use phase was not included in this assessment because USLCI databases for different elements of the modeling of the two
the structural materials are not determinative in the choice compared structures. All the production processes of consumed
of materials used for the building envelope or for insulation. resources and waste management, as well as the transport involved
As this is a comparative assessment and both use phases are in each phase of the life cycle of both structures were modeled
with available secondary data.

4 Volume 2018; Issue 04

Curr Trends Forest Res, an open access journal

ISSN: 2638-0013
Citation: Laurent AB, van der Meer Y and Villeneuve C (2018) Comparative Life Cycle Carbon Footprint of a Non-Residential Steel and Wooden Building Structures.
Curr Trends Forest Res: CTFR-128. DOI: 10.29011/ 2638-0013. 100028

Arena Structures Mass Balance origin and technological performance. Our study concerns the
reference year 2009. The geographical context is an arena in
The components used to model the hybrid structure, the Quebec. The construction is specific to the Saguenay-Lac-Saint-
constructed arena, are detailed in (Table 1). The building’s hybrid Jean region, but some data are aggregated for North America as
structure is composed of a hollow steel structure, a wide steel a whole.
section and wood glulam beams assembled by screws, nuts and
bolts that are presented in the mass balance. The components used In general, the available Life-Cycle Inventory (LCI)
to model the full steel frame arena structure are detailed in (Table databases are not representative of specific reality, as the analysis
2). presented here would require. Data from ecoinvent, which is the
most comprehensive database at present, presents averages of
Material Quantity Unit technology impacts that have not necessarily been updated and
Glulam section 110.95 m3 that are mostly derived from the European context. We adapted this
Hollow structural steel 5.68 Metric ton databank to the Quebec context for activities that took place in this
Wide flange section 83.22 Metric ton province. The ecoinvent data concerning energy supply have been
Screws, nuts & bolts 4.24 Metric ton
adapted to Quebec’s energy grid (grid mix) to replace the various
Table 1: Hybrid structure mass balance. European energy sources. This includes, for example, modifying
the distribution percentages of the various countries supplying
Material Quantity Quantity
crude oil resources [15] and sources of electricity production in
Wide flange section 196.88 Metric ton
Quebec, which was in 2009, 97% produced by hydropower [27].
Screws, nuts & bolts 10.04 Metric ton
Thus, all the foreground processes, such as industrial process and
Table 2: Steel structure mass balance. transportation, use background processes adapted to the Quebec
In comparison with the modeling of the current arena, the energy context.
111 m3 of wood glulam used for the structure above the ice has In addition, the type and consumption of the various vehicles
been replaced by 114 tons of steel. The other structural components used have been adapted from the ecoinvent database. For example,
for the administrative offices, for the machinery rooms, for the a noticeable difference is observable between the typical European
players’ rooms and for the internal platforms are the same. city vehicles with gasoline modeled in the database and a pickup
truck traveling on forest roads. Therefore, we made some changes,
Delivery Stage such as the mass of the vehicle and the fuel consumption to adapt
Fuel consumption was estimated with information received it to the North American context. The vehicle modeling available
from suppliers of the two materials studied, distances traveled in ecoinvent is based on a Volkswagen Golf; the weight is barely
and national average fuel consumption by type of truck used. higher than one ton and the consumption is representative of
This energy consumption served as an input into the model and the average consumption of European vehicles in 2005. We
was adapted to represent North American truck transport. The have therefore modified the quantity of steel in the inventory as
delivery distance of the steel was modelled from Toronto (ON) well as all emissions by a factor of 2.14 so that it represents a
to Chicoutimi (QC) (1 003km) since a large majority of the steel pick-up whose consumption is on average 16.8 l / 100km (GHG
used in the arena structure comes from the Great Lakes region protocol, 2009). In addition, we reduced the impacts to 10 percent
(personal communication with Picard Steel, 2011). The transport attributable to the manufacture, use and maintenance of road
distance of glulam is real because it is determined from a known infrastructures, since these pick-ups would only be running one
production site in Chibougamau (QC) (358km from Chicoutimi). tenth of the time on paved roads, according to silvicultural workers
Both delivery distances were estimated by using googlemaps. consulted. Data specific to several other vehicles, mainly related to
forest transport, were also adapted for the purposes of the study.
Requirements for Data Quality We have paid particular attention to disaggregate and document
Data quality requirements, according to the ISO standard, the data collected. (Tables 3) present the approach advocated and
must at least ensure their validity in terms of age, geographical are inspired by Weidema [28].

5 Volume 2018; Issue 04

Curr Trends Forest Res, an open access journal

ISSN: 2638-0013
Citation: Laurent AB, van der Meer Y and Villeneuve C (2018) Comparative Life Cycle Carbon Footprint of a Non-Residential Steel and Wooden Building Structures.
Curr Trends Forest Res: CTFR-128. DOI: 10.29011/ 2638-0013. 100028

Temporal Geographic Further technological

Life cycle stages Reliability Completeness Sample size
correlation correlation correlation
Steel production 3 3 3 2 3 2
Glulam production 1 2 1 1 1 1
Delivery 1 2 1 1 1 4
Building 1 2 1 1 1 4
Decontruction 3 4 5 1 5 5
End of life 3 3 5 3 5 5

Table 3: Data quality matrix.

Results
Since this study is limited to the impact of GHG emissions
and their contributions to climate change, we used the “ IPCC
2007 GWP 100a “ method for modeling GHG emissions [16].
This method is the result of a consensus of the most recognized
researchers in the field of climate change with a timeframe of 100
years. The “IPCC 2007” method mainly consists of characterizing
the different GHG emissions contributing to global warming and
then aggregating them into carbon dioxide equivalents (CO2-eq)
[16].
Application and Limits of the Carbon Footprint
Non-residential buildings are most often unique and
Figure 2: Comparative Greenhouse gas emissions of the hybrid and the
complex, making comparisons difficult [29]. It is therefore not
steel structure.
recommended to use the results of this study directly in a context
different from this study. The interpretation of the results has The first finding is that steel production has the largest
certain limitations, as demonstrated by the sensitivity analysis contribution to GHG emissions. It has a contribution of about 92%
in section sensitivity analysis. Transport is an element that can in the case of the entirely steel structure. In the case of the hybrid
significantly vary, and may even reverse the carbon gains from structure, steel production is also the main contributor with 70%
the use of lumber in a building. In addition, the completeness and of GHG emissions while it accounts for only 45% of the mass
validity of the inventory data and the assumptions used also limit of materials. The contribution of glulam production is 13%. The
to the conclusions that can be drawn. second contributor, in order of importance, is associated with the
stages of building and deconstruction in both cases.
GHG Emissions Results
In this study, transportation distances are short, so it is not
(Figure 2) presents the GHG emission results of the two a hotspot in the life cycle carbon footprint. Nevertheless, glulam
types of structures studied. These results consider carbon emissions beams are transported on longer distances and mainly by truck, as
for all the processes described in the inventory for both types of shown in [8], and therefore this phase may be a bigger contributor
structures over the entire life cycle. The hybrid structure, steel and than glulam manufacturing emissions from cradle-to-gate. In these
wood, totaling 111 m3 of wood glulam, reduced the amount of steel cases, it is advised to use an alternative mode of transportation that
required for the construction of the arena by 55%, on mass based could help to minimize the reduction of emissions [30,31].
evaluation. This structure emits 120 tCO2-eq, while that of steel
would have emitted 203 tCO2-eq. So using wood in the structure The end-of-life of wood products is probably the phase
reduced the emission of 83 tCO2-eq, or resulted in a 40% reduction where it is easiest to reduce the carbon footprint, even if the impact
of greenhouse gas emissions. is low. Indeed, the use of the wooden material for energy purposes

6 Volume 2018; Issue 04

Curr Trends Forest Res, an open access journal

ISSN: 2638-0013
Citation: Laurent AB, van der Meer Y and Villeneuve C (2018) Comparative Life Cycle Carbon Footprint of a Non-Residential Steel and Wooden Building Structures.
Curr Trends Forest Res: CTFR-128. DOI: 10.29011/ 2638-0013. 100028

would allow a possible substitution of fossil fuel, thus reducing the

net carbon balance.
Uncertainty Analysis
Monte Carlo uncertainty analysis was performed in Simapro
software to determine the extent to which a difference between
two scenarios is significant, as explained by [32]. The results of
this analysis are presented in (Figure 2), in which the “l” at the top
of the bars represents the standard deviation on the GHG emissions
result.
The USLCI data have the advantage of presenting processes
that are more representative of North American practices. On
Figure 3: Steel production sensitivity analysis.
the other hand, uncertainty is not available in this source, which
removes much relevance to uncertainty analyzes on these data. As shown in the results, GHGs emitted during steel
With a variability of 2.54%, the uncertainty of the hybrid structure production greatly influence the carbon footprint of both types
is higher than the steel structure, which is 0.72%. This difference is of structures. When ecoinvent data are used to model the hybrid
explained by the lack of variability given for the steel production in structure, its carbon footprint becomes greater than the original
the USLCI database. Nevertheless, this lack of precision reinforces all-steel structure. However, when compared with the full steel
the relevance of addressing, through a sensitivity analysis, the structure calculated with the ecoinvent data for steel production,
variability of GHG emissions related to steel production. This the hybrid structure maintains a significant advantage in terms
analysis is integrated in the following section. of GHG emissions. That result shows how the model for steel
production influences the GHG results.
Sensitivity Analysis
As mentioned above several parameters used in the End of Life Scenarios of Wood Glulam
model present uncertainties. We have also put forward several End-of-life scenarios can vary from landfilling to energy
assumptions to make it possible to determine the carbon footprint valorization. As we cannot determine the material valuation rate
of the two types of structures studied. We tested the robustness that will be applied when the arena is demolished, we propose to
of those parameters. The variability of the GHG emissions results evaluate the variation between 0 and 100%. We have assumed that
demonstrates the importance of the modified parameters. the GHG emissions are a linear function of reduced landfill, which
gives the slope represented in (Figure 4).
GHG Emissions from Steel Production
Initially we used the USLCI database because it is
representative for North American practices. So for modeling
the steel production we used the inventory name “Iron and steel,
production mix/US”. In order to verify the robustness of this
main contributor a sensitivity analysis was performed on the steel
production. We resorted to the reinforcing steel produced outside
of Europe (ROW stands for Rest of the World) of the ecoinvent
database. With the IPCC method, the GHG emission factor is
two kgCO2-eq. / kg of steel, compared with 0.91 kgCO2-eq. / kg
of steel based on the USLCI data. This notable difference is due
to a recycling rate of 56% using the cut-off rule in the USLCI
model, as explained in the documentation [33]. On the other hand,
the recycling of steel is not taken into account in ecoinvent [34], Figure 4: Sensitivity analysis of wood glulam end of life scenarios.
probably because of a lack of reliable data. The reality is probably
between these two values, which justifies the use of a sensitivity In contrast with the very conservative scenario “everything
analysis. to landfill”, the 100% valuation scenario can be qualified as very
optimistic. Indeed, the modeling of an energetic valorization of all
(Figure 3) illustrates the results of the sensitivity analysis on the glulam would be only thermal, since the reduction of the carbon
emissions from steel production. impact for electricity is not advantageous in terms of substitution in

7 Volume 2018; Issue 04

Curr Trends Forest Res, an open access journal

ISSN: 2638-0013
Citation: Laurent AB, van der Meer Y and Villeneuve C (2018) Comparative Life Cycle Carbon Footprint of a Non-Residential Steel and Wooden Building Structures.
Curr Trends Forest Res: CTFR-128. DOI: 10.29011/ 2638-0013. 100028

Quebec, because of the already very low GHG impact of electricity Carbon Balance of the Entirely Wooden Structure
supply in the province. The use for energy purposes of 111 m3 of In order to add the entirely wooden structure to the carbon
wood allows the substitution of 800 GJ of fossil fuel, or about 30 footprint comparison in this study, the same methodology,
m3 of natural gas. In addition, we considered that the combustion functional unit and assumptions were used.
of wood glulam is possible directly near the site of the UQAC
(hospital complex boiler), without significant transportation and (Figure 5) presents the result of the carbon footprint of
wood chips are produced with an electric grinder. the whole-wood structure in comparison with the two structures
studied earlier. It is easily identifiable that the carbon impact of
This valuation provides GHG emission reductions of 2.4 the structure made entirely of wood is lower than the two others,
tCO2-eq, a reduction of 1.7% in the balance sheet of the hybrid with emissions of the order of 58.6 tons of CO2-eq. So, the wooden
structure. This is a low contribution on the final result. structure would have emitted only half of the GHG emissions
Discussion of The Results from the real (hybrid) structure and one quarter of the total GHG
emissions of the steel structure. The figure shows a distribution of
In this section, we will expand the scope of the study. In the the contribution of the impacts and results show that the production
first part, we will try to answer the question: what could be the of glulam greater contribution to the wood structure GHG impact
carbon footprint of a whole-wood structure? The second part of the (37%) than steel production with 22% of the overall GHG impact.
section aims to calculate the potential sequestration of carbon in This is due to the low amount of steel needed for this structure.
the structure by integrating biogenic carbon into the accounting.
Entirely Wooden Structure
Modern wood construction techniques make it possible to
build large wooden structures. Some arenas, such as the Richmond
Olympic Oval (BC) or the Anaheim ice arena (CA) have a structure
with a large proportion of wood. There does not seem to be any
disadvantage from the point of view of the technical feasibility of
proposing a structure entirely made of wood, even if there is still a
need for steel for screws and supports.
It is possible to determine the amount of wood glulam
required for a whole-wood structure, by using the software Athena
(Athena Sustainable Materials Institute, Ottawa, ON). Given the
contribution of steel in the hybrid structure to GHG emissions, it
is interesting to conduct the exercise as to determine the carbon Figure 5: Wood structure carbon footprint comparison.
footprint of such a structure. These results suggest that maximizing the use of glue-
Modeling The Structure of the Arena Completely in Wood laminated wood in the construction of non-residential buildings
with related structural configurations appears to have positive
The components used to model the structure of the arena effects on the carbon footprint.
completely in 100% glulam are detailed in (Table 4).
Biogenic Carbon Accounting
Material Quantity Unit
Glulam section 186.65 m3 Accounting for the biogenic carbon sequestered in
Hollow structural steel 9.84 Metric ton harvested wood products is still under discussion [35-37]. From
Screws, nuts & bolts 4.24 Metric ton each standard, biogenic carbon must be accounted, but must
Table 4: Wood structure mass balance. be separately presented [38,39]. Since the Quebec forest is
sustainably managed and registered under recognized certification,
In comparison with the current arena hybrid structure, the mainly Forest Stewardship Council (FSC), Canadian Standards
83 tons of steel used for the structure of administrative offices, Association (CSA) or Sustainable Forestry Initiative (SFI), the
machinery rooms, players’ rooms and internal platforms were wood procurement does not result in net deforestation in addition
replaced by 76 m3 of glued laminated wood in the modeling carried to other environmental criteria such as biodiversity, aquatic effects
out with the Athena software. and soil impact [40].

8 Volume 2018; Issue 04

Curr Trends Forest Res, an open access journal

ISSN: 2638-0013
Citation: Laurent AB, van der Meer Y and Villeneuve C (2018) Comparative Life Cycle Carbon Footprint of a Non-Residential Steel and Wooden Building Structures.
Curr Trends Forest Res: CTFR-128. DOI: 10.29011/ 2638-0013. 100028

Obviously, wood contains carbon, because each carbon atom as building materials technology, such as glulam, is still under
in the wood is derived from an atmospheric CO2 molecule captured development in the non-residential construction sector in North
by photosynthesis. It is generally accepted that wood is composed America. The results of this case study show a net reduction in
of 50% biogenic carbon by dry mass in average [41]. Based on GHG emissions by using wood materials in the structure of a non-
of the Quebec’s glulam LCA study, the density is 520 kg/m3 and residential building. The construction of the hybrid structure has
contains 22.5 kg of residual glue. That corresponds to 249 kg of saved 83 tons of CO2-eq, or 173 tCO2-eq when the positive effect
carbon, or 914 kg CO2 per m3 of glulam. By subtracting the 102 kg of biogenic carbon sequestration is taken into account.
emitted throughout the entire manufacturing cycle, a cubic meter
Given the result of the comparison with the entirely wooden
of Quebec’s wood glulam sequesters a net 812 kg of CO2 [8].
structure, the University could have reduced the impact of climate
According to these estimates, (Figure 6) presents the change by an additional 61 tCO2-eq (and 122 tCO2-eq, including
integration of biogenic carbon in the LCCF results. This calculation biogenic carbon) by using more wood in its arena structure.
makes the wood structure even more advantageous by doubling
Although the wood material has already been documented as
the difference between the hybrid and steel structure total carbon
a lower emitter than steel over the entire life cycle, within the context
emissions. By sequestering more carbon than anthropogenic
of Quebec it is particularly favorable as non-residential building
emissions in the whole-wood structure, it could be carbon negative.
material. The availability of raw materials and their renewable
In terms of mitigation of climate change this makes the use of
nature are fundamental elements, and the low carbon intensity
wood even more interesting than other types of materials as carbon
of electricity in the Quebec network contributes to consolidating
negative measures are requested to fulfill the goal of the Paris
these advantages. Indeed, much of the energy consumed by the
Accord to keep climate warming “well under 2 degrees before
forest industry is electrical, especially for sawing. The general
2100”. It should be noted that when the material is decomposed
conclusions were drawn from a site-specific study. However, this
after use, e.g. by energy valorization, the sequestered carbon is
study can reinforce the interest for non-residential wood buildings
released again. However, when all such structures would be wood-
in the light of greenhouse gas emission reduction, especially when
only, it could significantly contribute to carbon sequestration over
wood procurement can be certified for sustainable management of
time periods of 75 years.
forests.
Finally, regarding the displacement factor mentioned in the
introduction, the indices calculated from the results of this case
study are between 0.83 tC/tC for the hybrid structure and 1.76 tC/
tC for the structure entirely made from wood, including biogenic
carbon sequestration accounting. The displacement factors in this
study are therefore below the average of 2.1 tC/tC calculated by
Sarthe & O’Connor (2010) and this demonstrates the need for
precise carbon footprint accounting to achieve GHG reductions
with wooden building materials.

References
1. Robichaud F, Kozak R, Richelieu A (2009) Wood use in nonresidential
construction: A case for communication with architects. For. Prod J
59: 57-65.

2. Martel JP (2013) Advanced Wood Building Systems: Growing the Ca-

Figure 6: Biogenic carbon integration. nadian Bio-economy. FP Innovation, Canada 2013.

Conclusion 3. Bowyer J, Bratkovich S, Howe J, Fernholz K, Frank M, et al. (2016)

Modern tall wood buildings: opportunities for innovation. Dovetail part-
This study aimed to quantitatively determine the life cycle ners inc., Minneapolis, MN, USA 2016.
carbon footprint of the hybrid structure of the Université du 4. Nabuurs GJ, Masera O, Andrasko K, Benitez-Ponce P, Boer R, et al.
Québec à Chicoutimi arena and to compare it to that of an entirely (2007) Forestry. In Climate Change 2007: Mitigation. Contribution of
steel-made structure modelled for the same building. Based on Working Group III to the Fourth Assessment Report of the Intergov-
the nature of the specific data used for a building constructed in ernmental Panel on Climate Change [B. Metz, O.R. Davidson, P.R.
Bosch, R. Dave, L.A. Meyer (eds)]. Cambridge University Press, Cam-
2009 but expected to remain functional for a few decades. As such, bridge, United Kingdom and New York, NY, USA 2007.
this comparative assessment will remain relevant for a long time,

9 Volume 2018; Issue 04

Curr Trends Forest Res, an open access journal

ISSN: 2638-0013
Citation: Laurent AB, van der Meer Y and Villeneuve C (2018) Comparative Life Cycle Carbon Footprint of a Non-Residential Steel and Wooden Building Structures.
Curr Trends Forest Res: CTFR-128. DOI: 10.29011/ 2638-0013. 100028

5. Sartori I, Hestnes AG (2007) Energy use in the life cycle of conven- 23. O’Connor J, Kozak R, Gaston C, Fell D (2004) Wood use in nonresi-
tional and low-energy buildings: A review article. Energy Build. 39: dential buildings: Opportunities and barriers. For Prod J 54: 19-28.
249-257.
24. Winistorfer P, Chen Z J, Lippke B, Stevens N (2005) Energy consump-
6. Sathre R, O’Connor J (2010) A synthesis of research on wood prod- tion and greenhouse gas emissions related to the use, maintenance,
ucts and greenhouse gas impacts- 2nd edition (No. TR-19R). FPIn- and disposal of a residential structure. Wood Fiber Sci. 37: 128-139.
novations, Canada 2010. 25. Rios, FC, Chong WK, Grau D (2015) Design for Disassembly and De-
7. Purnell P (2011) Material Nature versus Structural Nurture: The Em- construction - Challenges and Opportunities. Procedia Eng., Defining
bodied Carbon of Fundamental Structural Elements. Environ. Sci. the future of sustainability and resilience in design, engineering and
Technol 46: 454-461. construction 118: 1296-1304.

8. Laurent AB, Gaboury S, Wells JR, Bonfils S, Boucher JF, et al. (2013) 26. Chini AR (2005) CIB Final Report of Task Group 39 on Deconstruc-
Cradle-to-Gate Life-Cycle Assessment of a Glued-Laminated Wood tion. CIB, International Council for Research and Innovation in Building
Product from Quebec’s Boreal Forest. For. Prod J 63: 190-198. Construction, Delft, The Netherlands 2005.
27. MERN (2014) Production d’électricité. Ministére de l’Energie et des
9. ISO (2006) ISO 14044:2006. Environmental management -- Life cycle
Ressources Naturelles du Québec, QC, Canada.
assessment -- Requirements and guidelines. International Standards
Organization, Geneva, Switzerland 2006. 28. Weidema BP, Wesnaes MS (1996) Data Quality management for life
cycle inventories - an example of using data quality indicators. J Clean
10. ISO (2012) Carbon footprint of products —Requirements and guide-
Prod 4: 167-174.
lines for quantification and communication. International Standard Or-
ganization, Geneva, Switzerland 2012. 29. Salazar J, Sowlati T (2008) A review of life-cycle assessment of win-
dows. For Prod J 58: 91-96.
11. Onat NC, Kucukvar M, Tatari O (2014) Scope-based carbon footprint
analysis of U.S. residential and commercial buildings: An input–output 30. Bauer J, Bektaş T, Crainic TG (2010) Minimizing greenhouse gas
hybrid life cycle assessment approach. Build. Environ. 72: 53-62. emissions in intermodal freight transport: an application to rail service
design. J Oper Res Soc 61: 530-542.
12. The Athena Institute (2004) Minnesota demolition survey: phase two
report. ATHENA soustainable materials institute, Canada 2004. 31. Laurent AB, Vallerand S, Van der Meer Y, D Amours S (2018) Carbon-
RoadMap: A Multi-Criteria Decision Tool for Multi-modal Transporta-
13. Markus Engineering Services (2002) Cradle-to-Gate Life Cycle In- tion. Int. J. Sustain. Transp. in publication process 2018s.
ventory for Canadian and US Steel Production by Mill type. ATHENA
soustainable materials institute, Canada 2002. 32. Jolliet O, Saade-Sbeih M, Shaked S, Jolliet A, Crettaz P (2015) Envi-
ronmental Life Cycle Assessment. CRC Press, Boca Raton, FL, USA
14. Vachon JFL, Beaulne-Bélisle K, Rosset J, Gariépy B, McGrath K 2015.
(2009) Profil des gestion des débris de construction, rénovation et dé-
33. NREL (2013) USLCI data documentation on Iron and steel, production
molition (CRD) au Québec. RecyclQuebec, QC, Canada 2009.
mix. National Renewable Energy Laboratory, Golden, CO, USA 2013.
15. MERN (2014) Importations et exportations de pétrole et de produits
34. Classen M, Althaus HJ, Blaser S, Scharnhorst W (2009) Life Cycle
pétroliers. Ministére de l’Energie et des Ressources Naturelles du
Inventories of Metals ecoinvent v2.1, 926. Ecoinvent, Zurich, Switzer-
Québec, QC, Canada 2014.
land 2009.
16. Frischknecht R, Jungbluth N, Althaus HJ, Doka G, Heck T, et al. (2007) 35. Bergman R, Puettmann M, TaylorA, Skog KE (2014) The Carbon Im-
Ecoinvent: Overview and methodology. Data v2.0. Ecoinvent, Zurich, pacts of Wood Products. For Prod J 64: 220-231.
Switzerland 2007.
36. Pingoud K, Soimakallio S, Perälä AL, Pussinen A (2003) Greenhouse
17. IPCC (2007) Fourth Assessment Report: Climate Change 2007 (AR4). gas impacts of harvested wood products Evaluation and development
IPCC, Geneva, Switzerland 2007. of methods. VTT, Finland 2003.
18. BSI (2008) PAS 2050:2008 - Specification for the assessment of the 37. van Kooten G (2009) Biological carbon sequestration and carbon trad-
life cycle greenhouse gas emissions of goods and services. The Brit- ing re-visited. Clim. Change 95: 449-463.
ish Standards Institution, London, United Kingdom 2008.
38. Bhatia P, Cummis C, Draucker L, Rich D, Lahd H, et al. (2011) Green-
19. WRI-WBCSD (2010) Product Accounting & Reporting Standard; sec- house Gas Protocol Product Life Cycle Accounting and Reporting
ond draft for stakeholder review. World Resources Iinstitute - World Standard. World Resources institute - World Business Council for
Business Council for Sustainable Development, Washington, D.C., Sustainable Development, Washington, D.C 2011.
USA 2010.
39. BSI (2011) PAS 2050:2011 - Assessing the life cycle greenhouse gas
20. Newell JP, Vos RO (2012) Accounting for forest carbon pool dynamics emissions of goods and services. The British Standards Institution,
in product carbon footprints: Challenges and opportunities. Environ. London, United Kingdom 2011.
Impact Assess Rev 37: 23-36.
40. Bourgeois L, Kneeshaw D, Imbeau L, Bélanger N, Yamasaki S, et al.
21. Syed AM, Kośny J (2006) Effect of Framing Factor on Clear Wall R- (2007) How do Alberta’s, Ontario’s and Quebec’s forest operation laws
value for Wood and Steel Framed Walls J Build Phys 30: 163-180. respect ecological sustainable forest management criteria in the bo-
real forest? For Chron 83:61-71.
22. Lyons M (2009) A comparative analysis between steel, masonry and
timber frame construction in residential housing. University of Pretoria, 41. Ter-Mikaelian MT, Colombo SJ, Chen J (2008) Fact and fantasy about
South Africa 2009. forest carbon. For. Chron. 84: 166-171.

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Curr Trends Forest Res, an open access journal

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