Sustainable timber building and its carbon emission analysis in the LINE-NEOM

Full text

Full Terms & Conditions of access and use can be found at
https://www.tandfonline.com/action/journalInformation?journalCode=umcm20
Mechanics of Advanced Materials and Structures
ISSN: (Print) (Online) Journal homepage: https://www.tandfonline.com/loi/umcm20
Sustainable timber building and its carbon
emission analysis in the LINE-NEOM
Danish Ahmed, Samar Dernayka, Saidur R. Chowdhury, Andi Asiz & Tahar
Ayadat
To cite this article: Danish Ahmed, Samar Dernayka, Saidur R. Chowdhury, Andi Asiz
& Tahar Ayadat (28 Sep 2023): Sustainable timber building and its carbon emission
analysis in the LINE-NEOM, Mechanics of Advanced Materials and Structures, DOI:
10.1080/15376494.2023.2262978
To link to this article: https://doi.org/10.1080/15376494.2023.2262978
Published online: 28 Sep 2023.
Submit your article to this journal
Article views: 82
View related articles
View Crossmark data

ORIGINAL ARTICLE
Sustainable timber building and its carbon emission analysis in the LINE-NEOM
Danish Ahmed, Samar Dernayka, Saidur R. Chowdhury, Andi Asiz, and Tahar Ayadat
Department of Civil Engineering, Prince Mohammad Bin Fahd University, Al Khobar, Saudi Arabia
ABSTRACT
Timber is arguably the oldest construction materials that human have used since the dawn of civiliza-
tion. Since the last few centuries, the invention of concrete and steel materials has limited timber
uses to small and medium structural applications. The renaissance of timber construction has been
felt recently due to the emergence of engineered massive timber elements that can perform similar
structurally to that of concrete. The main objective of this paper is to study feasibility using massive
timber element in building to be constructed in the futuristic city LINE-NEOM, Saudi Arabia. The
main motivation of this study is the sustainability aspect of timber that can contribute to zero carbon
emission for buildings, which will be one of the major environmentally friendly goals for LINE.
Literature survey was conducted to demonstrate that timber is promising construction material for
future building. A comparative case study of multi-story building constructed using traditional
reinforced concrete and massive timber elements was performed. One particular type of massive
timber element called Cross Laminated Timber (CLT) was used in this study. Key structural perform-
ance of building was compared using applicable design code criteria. Furthermore, carbon emission
of buildings constructed with reinforced concrete and CLT was analyzed and compared. The struc-
tural analysis and design results indicated that the CLT building was acceptable in term of lateral
deformation or drift under critical combination of lateral and gravity loads. The carbon emission com-
parison showed that CLT building outperformed the reinforced concrete building significantly. As
was anticipated, the CLT building stored significant amount of carbon making it an excellent alterna-
tive materials for buildings in LINE that has goal to be zero-net carbon’s city.
ARTICLE HISTORY
Received 15 May 2023
Accepted 21 September 2023
KEYWORDS
Massive timber; CLT;
structural performance;
sustainable building; carbon
emission; LINE-NEOM
1. Introduction
The trend to construct tall timber buildings has recently
been on rise around the world, notably in North America,
Europe, Australia, and Japan. The major driver for this
trend is to support sustainability development goal in add-
ition to the basic construction constraint, high performance
construction with minimized cost. The concept of timber
use in buildings has initially aroused when people intro-
duced engineering wood product (EWP) around the last
mid-century as substitute for solid sawn wood. EWP is cre-
ated to minimize the inherent defects carried by solid wood
such as knots, checks and cracks by combining lamination
technology with optimizing wood grain orientation to
achieve consistent strength and properties. The first gener-
ation of EWP included glue-laminated timber (glulam),
Plywood, laminated veneer lumber (LVL), parallel strand
lumber (PSL), oriented strand board (OSB), oriented strand
lumber (OSL), Wood I-Joist, etc. [1]. The structural effi-
ciency of these products was actually attributed to optimiz-
ing the Lignin orientation as the governing strength-
determining component of wood [2]. The majority of these
products were used in light-frame constructions such as
residential and low-story commercial buildings, in addition
to versatile glulam beams that were used in heavy structures
including short span and cantilevers [3]. In North America
alone, EWP has dominated residential construction material
use constituting nearly 90% of its framing. Since early 90s,
however, the use of EWP has saturated and timber has faced
very competitive challenges from other construction materi-
als in order to penetrate nonresidential sectors such as tall
buildings and long-span structures. Near the end of 90’s, a
second generation of EWP was introduced into the
European construction utilizing combination of wood fiber
orientation with dimensional massiveness applied through
multilayer adhesive-based lamination. It is similar concept
applied to that glulam timber beam, but this time it is in the
form of plate with cross lamination layer to create uniform
characteristics in both directions. This product is specifically
called cross-laminated timber (CLT) plate (Figure 1). CLT is
versatile in building design and construction; it can be used
horizontally as slab element or vertically as structural wall
elements and non-load bearing wall partitions. With appro-
priate connectors, CLT can be used in combination with
steel frame or reinforced concrete elements as hybrid or
composite construction system. The multi-story building
construction utilizing CLT and other EWP has been boom-
ing since CLT gained reliability recognition from structural
engineers in low-rise construction.
CONTACT Danish Ahmed dahmed@pmu.edu.sa Department of Civil Engineering, Prince Mohammad Bin Fahd University, Al Khobar, Saudi Arabia.
This article has been corrected with minor changes. These changes do not impact the academic content of the article.
� 2023 Taylor & Francis Group, LLC
MECHANICS OF ADVANCED MATERIALS AND STRUCTURES
https://doi.org/10.1080/15376494.2023.2262978

The nine-story Stadthouse Murray Grove Apartment
Complex in London, UK is one of the first multi-story
buildings constructed using massive timber elements as
designed by Waugh Thistleton Architects [4]. The building,
completed and occupied in 2009, uses CLT as the vertical
wall bearing and horizontal slab elements without any
beams and columns. The building has its first story rein-
forced concrete frame with the main intention to prevent
timber elements in direct contact with water or moisture.
Major features and advantages of this building relative to
reinforced concrete includes shorter construction time,
higher thermal performance, and better environmental
impact. Later, there have been several multi-story building
constructions utilizing CLT as the main materials along with
other massive glulam beam elements. For instance, Brock
Commons tallwood house is one of the most famous resi-
dential tall buildings constructed mainly with timber.
Currently, it represents the tallest mass timber building in
Canada, Vancouver; and at the time it was primarily occu-
pied in 2017, it was the tallest mass timber structure in the
world. The building, incuding 18-story with 53 m total
height, is actually a hybrid system, where the core-shear
walls use reinforced concrete and the remaining framing are
with CLT (slabs and walls) and glulam (beams and col-
umns). And timber, due to its lightness fulfilled the design
requirement of sustaining earthquake loads better relative to
that had the building was designed fully with reinforced
concrete elements. In terms of retrofitting, experiments have
proved that timber beams can be efficiently retrofitted on
site as reported by [5] by using means of carbon composite
material. The bending load capacity of the damaged beams
can be actually recovered, and it may even be increased by
70% with respect to the non-broken ones.
Although, the timber culture is expanding worldwide
among engineers and designers, it is often subject to few
obstacles such as the availability of resources and building
code regulations. The European market leads the production
and consumption of CLT and its utilization in building con-
struction, followed by the Canadian market. In the US, only
4.3% of American architects are aware of CLT [6] despite
90% of the American residential construction is made of
wood. Currently, CLT manufacturing facilities are being
open in US., Australia and East Asian countries like Japan.
South Korea and China are also starting introducing CLT to
the market using their local wood species. Other countries
are in the stage of research to develop CLT material from
local hardwood species and need to investigate further
building connection systems that can handle the propensity
of hardwood to splitting failure [e.g. 7].
On the other hand, the development of timber construc-
tion in ‘non-timber countries’ is still in its infancy level like
in the Middle East region. Few countries are working on
replacing the traditional construction materials with others
that are more sustainable. Recently, the Kingdom of Saudi
Arabia has started to adopt innovative construction solu-
tions such as prefabricated light-weight structural compo-
nents and hybrid modular building systems. Construction
festivals conferences and newly launched projects are hugely
marketed for various types of wood such as Nordic Wood,
Pine wood timber, and Light Wood types. In addition, the
government is encouraging further foresting to increase the
6% forestry in the empty areas. According to a report pub-
lished in October 2022 in Data Bridge Market research,
Saudi Arabia is expected to lead the wood market by 2030
under three main drivers: 1) the rising demand in commer-
cial and residential building sector, 2) The growing use in
packaging and transportation applications and 3) The rising
importance of light wood material. In fact, the timber con-
struction will meet the strict requirements of the carbon
neutral country plan of the Kingdom by 2060. As sustain-
able timber, light wood is a potential alternative for building
homes, decorations, furniture, exterior design, and products
such as paper, picture frames, shelves, cabinets, wardrobes,
garden fences, planter boxes, and others. Its key benefit over
hardwood is its lightweight and low density. Similarly, light
wood species may develop quickly while producing high-
quality timber. Lightwood has the potential to be a game
changer in the building sector. Because these species grow
quickly, one can obtain quickly, high-quality, and sustain-
able wood and other wood products. As a high-quality tim-
ber building material, light wood may give a strategic
advantage as a timber business and has a distinctive stand-
ing in technical wood goods and modern mass timber con-
struction. Using wood to its full potential allows one to
enhance the impact of climate advantages such as CO2
sequestration (forest carbon stock), CO2 storage (carbon in
materials), the substitution of high-emission products, and
recycling (end of life cycle). And addition to offering strong
structural capabilities, thermal and acoustic qualities, and
other advantages, it also speeds up construction by 40 per
cent and makes better use of labor by 30 per cent and
decreases waste. Moreover, the combination of high-quality
Figure 1. Massive timber products: Glulam and CLT.
2 D. AHMED ET AL.

with low quality timber can lead a more economical and
sustainable cross section, which is reflected in the improve-
ment in the modulus of elasticity and resistance to tension
and compression [8].
Therefore, timber will be a main driver in the sustainable
development and achievement of residential, commercial
and tourism projects. Currently, Mega and landmark infra-
structure projects accompanied with green initiatives have
been launched in the Kingdom to promote tourist industry
and attract more investors. Current landmark project the
LINE introduces Saudi and world communities a futuristic
smart and sustainable city designed in a 170 km long-line
(with 500 m high by 200m wide) across the northern desert
area of Saudi Arabia. The city is intended to be populated
with 9 million residents and will be equipped with various
modern infrastructures with no carbon emission, i.e. zero-
net carbon city [9]. It is an eye-catching project since it will
utilize renewable and abundant solar generated power to
run the city, and this is combined with utilization of various
green materials. The initial estimated cost to build this city
is 500 billion dollars. This will be a huge opportunity for
timber and timber-based materials to enter green construc-
tion market in Saudi Arabia with major sellable attribute as
the only carbon neutral or even carbon storage material.
On the other hand, only few papers have discussed the
structural performance of CLT buildings in the Kingdom in
specific with the increasing interest in timber construction.
The newly introduced CLT in Saudi structures will certainly
encourage researchers and engineers to examine closely the
building behavior under various loads, or at the foundation
level. [10] investigated the feasibility of using CLT slab in
the floor system of complex tall buildings situated in diffi-
cult soil conditions of Saudi Arabia. It has been found that
the CLT slab can be a substitute for the reinforced concrete
(RC) slab in complex tall building construction with a rela-
tive reduction in the foundation demand. The study in [11]
conducted a comparison of wind-induced response of high-
rise buildings with reinforced concrete and cross laminated
timber in two specific regions of the Kingdom (Dhahran
and Jeddah) under real wind loads. The analysis was con-
ducted in ETABS, verified in SAP 2000 and validated manu-
ally using Saudi Building Code. The results have clearly
showed that CLT slab is feasible and efficient in high rise
buildings in combination with a reinforced concrete skel-
eton. The lateral displacement of the building under wind
loads is still within the allowable drift.
Unlike concrete and steel, timber is renewable construc-
tion material that can be reproduced after certain period of
forest cultivation. This could be good in term of supporting
sustainability provided that the cultivation practice follows
responsible forest management. Majority of cultivated forests
in North America and Europe have been certified by inde-
pendent forest management agency, such as Sustainable
Forestry Initiative (SFI), Forest Stewardship Council (FSC),
and Program for the Endorsement of Forest Certification
(PEFC); to ensure that forest products comply with sustain-
able management criteria that provide environmental, social,
and economic benefits. Trees grown in the forest is actually
carbon sequester, converting carbon dioxide to biomass
through photosynthesis process that effectively stores car-
bon. Therefore, timber harvested under a certified forest can
be said as carbon sinker contributing to negative carbon
emission. One cubic meter of timber can store roughly 1
tons of carbon dioxide [12]. For 900 m
3
timber used, the
Stadhouse building stored around 310 tons of carbon instead
of releasing 124 tons of carbon had the building constructed
with reinforced concrete [4]. Table 1 shows carbon dioxide
emission during production (cradle-to-gate) for materials
commonly used in construction. Massive timber elements
such as CLT has big potential to be carbon negative or at
least carbon neutral. There have been several studies about
comparative analysis between concrete and timber used in
multi-story buildings, which favors timber over concrete in
term of carbon emission [13,14].
In terms of structural engineering performance, massive
timber structures perform well under seismic load due to
their inherent lightness with high strength-to-weight ratio.
There have been many studies demonstrating effectiveness
of massive timber structures loaded under dynamics earth-
quake. A group of European and North American timber
engineers demonstrated via a full-scale shake table test that
multi-story CLT building can sustain a strong earthquake
without significant and permanent damages [15]. They
observed that the earthquake energy was efficiently dissi-
pated through many ductile connections distributed
throughout CLT’s plate-to-plate joints; while concrete build-
ings can only develop floor vibrations under seismic blasting
[16]. It is a common practice in timber joints to apply fas-
tening system using combination between long-screws and
concealed-slender metal connectors such that structural duc-
tile failure can be forced to occur in the connections rather
than in the brittle timber elements. As a hybrid system
involving steel frame skeleton, mid-rise building with mas-
sive timber plate element as horizontal diaphragms
responses well under seismic load. Asiz and Smith con-
ducted comparative studies between reinforced concrete and
CLT slabs used in hybrid multi-story buildings loaded under
extreme seismic loads [17]. They found that CLT slab per-
formed better responding to these seismic loads relative to
the reinforced concrete slab. Other studies confirmed this
finding [10, 18]. They also observed that the in-plane rigid-
ity of CLT diaphragms, which is important aspect to distrib-
ute lateral load to shear wall system, was comparable to that
of reinforced concrete slab.
The purpose of this paper is to explore the potential use
of massive timber element in buildings to be constructed in
LINE-NEOM using benchmark of reinforced concrete build-
ing. A case study using ten-story building constructed using
CLT and RC was performed. The building was selected to
represent a typical residential building for LINE with around
300 occupants. To accommodate 9 million people, it needs
Table 1. Carbon dioxide emission for common construction materials [13].
Material Carbon dioxide emission Unit
Steel 3,500 Kg CO2-eq / m
3
Concrete 260 Kg CO2-eq / m
3
Timber (laminated) 90 Kg CO2-eq / m
3
MECHANICS OF ADVANCED MATERIALS AND STRUCTURES 3

30,000 buildings. This corresponds to more than 176 build-
ings of this type per one-kilometer out of 170km of LINE.
The structural analysis and design of the buildings were
conducted in accordance to the applicable design building
code. Furthermore, carbon dioxide emission analysis was
conducted to these buildings to observe which one has more
positive environmental impact in term of carbon footprint.
2. Building model design and analysis
Three types of ten-story residential building with the same
total height (35.5 m) and same floor area (5640 m
2
) were
modeled and analyzed in this study. The first type (Building
A) was fully designed with CLT except for its first story
which is made of reinforced concrete frame to prevent direct
water contact. The second type (Building B) is designed
using entirely reinforced concreted (RC) that forms precast
slab and shear wall components. The third type (Building C)
is hybrid system between CLT floor slabs and RC precast
shear walls. By combining with concrete as hybrid (mix)
construction, CLT has more opportunities to be used for tall
building applications. Designing vertical column compo-
nents of tall building with timber could pose a long-time
performance issue due to creep-induced shortening.
Reinforced concrete or steel is relatively stable material
against creep and it is good for designing column and shear
wall components of tall buildings. While horizontal slab
components can be designed with CLT plate to improve lat-
eral load response due to earthquake or wind and at the
same time to reduce demand in the foundation system. In
order to avoid significant differential shortening, attention
to connection detailing is important when reinforced con-
crete shear wall and timber columns are used for tall
building.
The floor layouts were made the same for all buildings
including the arrangement of the wall bearing (shear wall)
locations. Figure 2 shows the 3D look and typical floor lay-
out of the buildings. Each building has first story height of
4 m and the rest story of 3.5m. The slab and wall dimen-
sions for each story can be seen in Table 2, and the details
in Figure 3. For all three types of buildings, all the structural
components (i.e. slabs and bearing walls) were analyzed and
designed under the standards of Saudi Building Code (SBC)
[19]. The basic building geometries (elevation and layout)
modeled in this study was taken from Eugenia [20], who
investigated construction management of tall building
entirely made of CLT.
Before carbon emission analysis, structural performance
of these three buildings were conducted to ensure that they
are acceptable to be constructed in LINE based on the local
jurisdiction, Saudi Building Code [19]. A special software
for designing and analysis tall buildings called ETABS was
used for this purpose [21]. Other than building geometries
and dimension of structural components, required inputs
for ETABS modeling were structural loads, mechanical
properties of materials, and connection between structural
components. Lateral loads (wind and earthquake) were
derived from SBC applicable in the LINE area,
Northwestern Region of Tabuk in Saudi Arabia (where the
maximum wind speed is 105 mph). While the superimposed
dead loads (SDL) and live loads (L.L) used were based on
Figure 2. Building model frame as designed in ETABS.
Table 2. Structural elements and thicknesses for building A, B and C.
Building A
Storey Floor slab elements and thicknesses Wall elements and thicknesses
1 Reinforced concrete, 300 mm Reinforced concrete, 300 mm
2 CLT, 200 mm CLT, 180 mm
3, 4, 5 CLT, 200 mm CLT, 160 mm
6, 7, 8 CLT, 200 mm CLT, 140 mm
9, 10 CLT, 200mm CLT, 120 mm
Building B
Storey Floor slab elements and thicknesses Wall elements and thicknesses
1 Reinforced concrete, 300 mm Reinforced concrete, 300 mm
2 Reinforced concrete, 300 mm Reinforced concrete, 300 mm
3, 4, 5 Reinforced concrete, 300mm Reinforced concrete, 300mm
6, 7, 8 Reinforced concrete, 300mm Reinforced concrete, 300mm
9, 10 Reinforced concrete, 300 mm Reinforced concrete, 300 mm
Building C
Storey Floor slab elements and thicknesses Wall elements and thicknesses
1 CLT, 200 mm Reinforced concrete, 150 mm
2 CLT, 200 mm Reinforced concrete, 150 mm
3, 4, 5 CLT, 200 mm Reinforced concrete, 150mm
6, 7, 8 CLT, 200 mm Reinforced concrete, 150mm
9, 10 CLT, 200mm Reinforced concrete, 150 mm
4 D. AHMED ET AL.

applicable residential load stated in SBC (i.e. SDL: 1 kN/m
2
and L.L: 2kN/m
2
). Except its own structural weight, the lat-
eral loads (wind and earthquake) were applied equally to all
buildings. Table 3 shows the details of mechanical properties
of CLT and concrete used in this study. All bearing walls
and floor slabs were modeled using shell element. For
Building A, the connections between the CLT floor slabs
and the CLT bearing walls were assigned as semi rigid with
the spring mechanical properties of 2 kN/mm spaced equally
on the center at 250 mm [17]. For Building B, the connec-
tions between RC wall bearing and RC floor slab were made
rigid as RC is relatively stiffer compared to that of CLT. For
Building C, the connection of between the RC bearing walls
to the CLT slab panels were assumed to be 2 kN/mm spaced
at 250 mm on the center. Figure 4 described schematically
the connection between RC wall and CTL slab [17]. All
building were assumed to be fixed to the foundation, no
rotation allowed.
Key structural performances that need to be satisfied
according to SBC included strength limit state and service-
ability limit states. Output from ETABS indicated that all
buildings analyzed in this study satisfied the strength criteri-
ons. With respect to the vertical deflection serviceability cri-
teria, critical deflections developed in the floor generated
from the combination of dead and live loads were within
the allowable value for all three buildings (i.e. 13.2 mm for
building A, 2.2 mm for Building B and 6.5mm for Building
C). For the lateral deflection (drift), Figure 5(a) shows the
drifts due to extreme wind and Figure 5(b) the story drifts
due to critical earthquake. Each graph presents the differ-
ence in story drifts for each building and it can be observed
that Building A drift is much higher than Building B drift
for both wind and earthquake analysis. Building C has drift
in between Buildings A and B. The critical drifts produced
for the wind load for the three buildings are within the
allowable drift according to SBC code, which is 1% of the
total building height having only masonry cantilever shear
wall structures. Overall, the structural performance of these
three residential buildings are acceptable to be constructed
in LINE.
2.1. Carbon emission analysis
The same three types of building (Buildings A, B, and C)
modeled and verified structurally above were to be cal-
cualted their carbon emissions based on cradle-to-gate
assessment (manufacturing to construction assessment). For
buildings with CLT components (Buildings A and C), car-
bon emission count will include reinforced concrete ele-
ments as Building A’s first sotry is made of RC frame and
Building’s C vertical frame elements is composed of RC
bearing wall panels. Also, it should be noted that RC con-
tains reinforcing steel bars that were assumed to occupy
1.5–2% of the RC cross sectional areas. Tables 4 and 5show
the total volume of building materials and the total weight
of elements used in Buildings A, B, and C, respectively.
These values were to be used as major input for carbon
emission calculation.
The CO
2
produced for the manufacture of structural con-
crete (using 15% of cement) is estimated to be 410 kg/m
3
assuming density of concrete is 2.3 g/cm
3
, and 1.9 tons of
CO
2
are emitted for every ton of steel produced [23,24].
Manufacturing concrete similarly requires energy, but the
chemical process of making cement itself also produces sig-
nificant amounts of carbon dioxide. According to Portland
Cement Association [25], about 0.9 pounds of CO
2
are pro-
duced for every pound of cement production. This emission
of CO
2
from cement was included in the manufacture of
structural concrete in this study. Approximately 1.787 tons
of CO
2
would be saved per ton of recycled steel used in any
Figure 3. Building layout.
Table 3. Basic properties of CLT material [22].
Property Concrete CLT
Directional property isotropic orthotropic
Density (kg/m
3
)2400 400
Elastic modulus (GPa) 25 E
1
¼9, E
2
¼4.5, G
12
¼0.5
Poisson’s ratio 0.25 �12 ¼0.3
Strength (MPa) 27.5 f
t-1
¼20, f
t-2
¼15, f
c-1
¼30, f
c-2
¼25, f
shear
¼5
Notation: E ¼modulus of elasticity; G¼modulus of rigidity; 1 ¼CLT major
direction; 2 ¼CLT minor direction; t¼tension; c ¼compression
Figure 4. Connection of RC bearing walls to CLT slab panels. [17].
MECHANICS OF ADVANCED MATERIALS AND STRUCTURES 5

construction project [24, 26]. The study found that each m
3
of CLT stores 676 kg of CO
2
[27]. Steel transport and use
also release approximately 7.9 grams of CO
2
per ton-kilo-
meter [26, 28]. However, there is no approximate data avail-
able for CO
2
emissions for CLT transfer to the construction
site. The average petrol car can produce the equivalent of
170.5 to 192 grams of CO
2
per kilometer (g CO
2
equivalent
per km) in 2022, while diesel cars average roughly 170.8
grams of CO
2
equivalent per km [29]. Waste recycling can
significantly reduce carbon emissions and help promote sus-
tainable development [30]. The carbon emissions from recy-
cling concrete, brick, steel, wood, and mortar were identified
as the key components of construction waste. Waste recy-
cling can significantly reduce carbon emissions and help
promote sustainable development. According to Wang [30]
recycling 1 ton (t) of construction waste can save 100.4 kg of
CO
2
equivalent emissions. Table 6 shows carbon emissions
from engineering materials used in building construction.
Structural materials such as cement, concrete, and steel
account for most of the embodied carbon emissions in mod-
ern building construction [31]. In particular, iron and steel
have the second-largest share of embodied energy and
carbon among all construction materials. According to
Huang [32], steel products alone account for nearly 35% of
the embodied carbon in buildings. Table 6 shows carbon
emissions or sinks from recycling or common engineering
materials used in building construction.
Building construction requires enormous quantities of
building materials. It first requires the extraction of the raw
materials, followed by their transformation into various fin-
ished building materials via manufacturing processes, and
finally their transportation to construction sites [31]. These
construction-related activities result in the emission of vast
amounts of greenhouse gases (GHGs), predominantly car-
bon dioxide (hereinafter denoted ‘carbon emission’). This
study did not cover the emissions from the shipping and
transportation of engineering materials to the construction
site or the carbon sink for using recycled concrete, brick,
steel, wood, and mortar in the building construction. It is
anticipated that the carbon emission due the shipping and
transporation is quite small relative to the material produc-
tions [31]. The carbon emission reduction due to scrapped
steel use or proper handling of construction demolitions was
not counted in the material selection. Moreover, energy and
fuel requirements for the CLT and concrete or steel produc-
tion came from electricity, natural gas, and diesel at the
facility [33]. The carbon emissions due to these activities
were not considered in the present study. However, other
construction-related emissions were measured in order to
determine the approximate amount of carbon emissions
from the three types of buildings constructed by concrete,
steel, CLT, or composite materials in the study.
The contributions of CO
2
production, sinks, and the
amount of C emissions were summarized in Tables 7–9for
the three different types of buildings (A, B, and C). The
Figure 5. (a) Story drift due to wind in x-direction and (b) story drift due to earthquake in x-direction.
Table 4. Total volume of building material.
Building Type Total Volume of concrete (m
3
) Total Volume of steel (m
3
) Total Volume of CLT (m
3
)
Building A 246 2.5 2442
Building B 3995 40 —
Building C 1460 15 1128
Table 5. Material and total weight by element type.
Building Type Element Type Material Total Weight (kN)
Building A Wall (Ground Floor) Concrete 6171
Floor and wall CLT 9592
Steel in wall 199
Building B Wall Concrete 46049
Floor Concrete 41157
Total concrete 87206
Steel in wall and slab 3216
Building C Wall Concrete 23024
Floor CLT 4282
Steel in wall 1176
6 D. AHMED ET AL.

equations (1) to (3) were used to measure the emission in
terms of CO
2
and C quantities. In order to determine the
amount of CO
2
contribution to the atmosphere from the pro-
posed three buildings, the air fraction was set at 0.38. The air
fraction is the ratio between the amount of GHG present in
the atmosphere and the total emission of CO
2
. Results showed
that the storage of CO
2
in a complete CLT building is 1510.3
tons, whereas instead of storing CO
2
, the emission is signifi-
cantly higher in RC buildings. The results show that increas-
ing CLT in any building reduces CO
2
emissions.
Amount CO
2
in tons ¼
Total Volnof building materials total ton of CO2
emitted=Volnof materialsÞ(1)
Carbon emission in ton
ð Þ
¼Production of CO2in ton 12=44ð Þ (2)
PPM of CO2in atmosphere ¼
total amount of C=2:12 109
 �air fraction (3)
Where: Air fraction is considered 0.38
The building sector adds to 40% of the total carbon emis-
sions worldwide [30]. In this study, the results obtained
from Tables 7–9recommended using CLT or hybrid build-
ings in order to reduce carbon emissions, and ultimately to
achieve zero carbon emission. It can be seen that CLT build-
ing of ten-story high with nearly 300 occupants could sink
around 400 tons of carbon, while reinforced concrete build-
ing emitted around 600 tons of carbon. To accommodate 9
million people as the LINE planned, it needs about 30,000
buildings of this type assuming linear demand for the resi-
dential unit. This means CLT can sink 12 millions of car-
bon, while RC building releases 18 millions of carbon.
Therefore, zero-carbon emission’s goal for building con-
struction in LINE is highly achievable, and the negative car-
bon emission can be used up to compensate other
Table 6. Carbon emission from engineering materials used in building construction.
Construction Materials CO
2
emission The amount of CO
2
sink References
Cement About 0.9 pounds of CO
2
produced
for every pound of cement.
— [25]
Concrete 410 kg of CO
2
produced for every m
3
for the manufacture of structural
concrete (density of concrete is
2.3 g/cm
3
),
— [23]
Steel production About 1.9 tons of CO
2
emitted for
every tons of steel produced
— [24, 26, 28]
Steel Transport and Uses Approximately 7.9 grams per ton-km — [26, 28]
CLT Approximately 170.5 to 192 grams of
CO
2
per kilometer (g CO
2
equivalent per km) in 2022
Each m
3
of CLT stores 676 kg of CO
2
[27, 29]
Concrete demolition 1 ton (t) of construction waste
produced 100.4 kg CO
2
— [30]
Discarded /scrapped Steel — Approximately 1.787 tons of CO
2
saved per ton of recycled steel
used
[24, 26]
Tables 7. CO
2
production from building A.
Types Total volume in m
3
CO
2
production in Tons Carbon emission in Tons CO
2
emission in PPM
Concrete in first story 247 101.2 27.6 0.1310
-7
Steel rebars 2.47 38.5 10.5 0.0410
-7
CLT slabs and walls 2442 −1650.9 − 450 –
Total amount 21510.3 2412
Notes. 1.9 tons of CO
2
are emitted for every tons of steel produced; each m
3
of CLT stores 676 kg of CO
2
.
Tables 8. CO
2
production from Building B.
Types Total volume in m
3
CO
2
production in Tons Carbon emission in Tons CO
2
emission in PPM
Concrete bearing walls and floor panels 3996 1638.2 446.6 2.110
-7
Steel rebars 40.0 623.8 170.1 0.810
-7
Total amount 2262 616.7
Notes. 1 ppm CO
2
¼2.1210
9
Tons of C; CO
2
produced for the manufacture of structural concrete (using 15% cement) is estimated at 410 kg/m
3
.
Tables 9. CO
2
production from Building C.
Types Total volume in m
3
CO
2
production in Tons Carbon emission in Tons CO
2
emission in PPM
Concrete bearing wall panels 1460 598.7 163.3 0.710
-7
Steel rebars 14.6 227.93 62 0.310
-7
CLT floor slabs 1128 −762 −207 -
Total amount 64.6 18.3
Notes. 1.9 tons of CO
2
are emitted for every ton of steel produced each m
3
of CLT stores 676 kg of CO
2
; 1 ppm CO
2
¼2.1210
9
tons of Carbon. Here, steel mass
in tons was calculated by wieght of steel (in kN) divided by gravitional acceration (e.g. 9.8 m
3
/sec).
MECHANICS OF ADVANCED MATERIALS AND STRUCTURES 7

construction activities that emit carbon. Utilizing CLT
instead of reinforced concrete will allow the building indus-
try to transition toward a more sustainable construction. In
the short run, switching to fossil-free fuels can reduce the
carbon footprint of CLT. In the long-run, carbon capture
and storage at the end-of-life of CLT buildings can provide
a net negative carbon footprint over the life cycle. Although
it is relatively small contribution relative to the material pro-
ductions, carbon emission from recycling assessment of CLT
at the end use of building need to be counted to complete
cradle-to-grave evaluation. This is ongoing work.
3. Conclusion
Based on the structural analysis and design of typical build-
ing to be used in LINE of NEOM, CLT has demonstrated
potential as an alternative construction material to trad-
itional RC. Structurally, CLT building can sustain a combin-
ation of gravity and lateral load for the intended location.
With respect to the carbon emission, CLT outperforms RC
due to its capability of storing significant amount carbon.
This result will have major impact on one of the LINE’s
goal of be net-zero city since building will be one of its
major constituents. Given its high strength-to-weight ratio,
easy installation, and esthetic qualities, CLT has become a
cutting-edge alternative material to steel and concrete in the
building constructions. Ongoing study is focused on hybrid
construction combining steel vertical elements with CLT
without compromising too much on the carbon emission.
The results from the present study confirm that hybrid
building can reduce the emission of carbon, thus contribu-
ting to sustainable infrastructure development. In conclu-
sion, it is recommended that the scale up of construction
using hybrid methods could be a future consideration of
efficiency improvements for different environmental
burdens.
Disclosure statement
No potential conflict of interest was reported by the author(s).
References
0[1] Forest Product Lab (FPL). Wood Handbook: wood as an
Engineering Material. U.S. Department of Agriculture. Forest
Service, Madison, Wisconsin, 2010.
0[2] K. Hofstetter, Ch Hellmich, J. Eberhardsteiner, and H.A. Mang,
Micromechanical estimates for elastic limit states in wood mate-
rials, revealing nanostructural failure mechanisms, Mech. Adv.
Mater. Struct., vol. 15, no. 6–7, pp. 474–484, 2008. DOI: 10.
1080/15376490802142387.
0[3] V. De Luca, and A. Della Chiesa, A creep non-linear FEM ana-
lysis of glulam timber, Mech. Adv. Mater. Struct., vol. 20, no. 6,
pp. 489–496, 2013. DOI: 10.1080/15376494.2011.627643.
0[4] Timber Research and Development Association (TRADA), Case
Study: stadthaus, 24 Murray Grove, London. TRADA
Technology Ltd. Buckinghamshire, UK, 2009.
0[5] F. J. Rescalvo, E. Suarez, C. Abarkane, A. CruzValdivieso, and
A. Gallego, Experimental validation of a CFRP laminated/fabric
hybrid layout for retrofitting and repairing timber beams,
Mech. Adv. Mater. Struct., vol. 26, no. 22, pp. 1902–1909, 2019.
DOI: 10.1080/15376494.2018.1455940.
0[6] M.F.L. Mallo, and O. Espinoza, Awareness, perceptions and
willingness to adopt Cross Laminated Timber by the architec-
ture community in the United Stes, J. Cleaner Prod., vol. 94,
pp. 198–210, 2015. DOI: 10.1016/j.jclepro.2015.01.090.
0[7] N. Mohd Yusof, P. Md Tahir, S. H. Lee, M. A. Khan, and R.
Mohammad Suffian James, Mechanical and physical properties
of Cross-Laminated Timber made from Acacia mangium wood
as function of adhesive types, J Wood Sci., vol. 65, no. 1, 2019.
DOI: 10.1186/s10086-019-1799-z.
0[8] C. Timbolmas, R. Bravo, F. J. Rescalvo, and M. Portela,
Transformed-section method applied to multispecies glulam
timber beams subjected to pure bending, Mech. Adv. Mater.
Struct., vol. 29, no. 27, pp. 6814–6823, 2022. DOI: 10.1080/
15376494.2021.1985665.
0[9] NEOM. 2022. https://www.neom.com/en-us/regions/theline
[10] D. Ahmed, T. Ayadat, and A. Asiz, Design and Performance of
High-Rise Structure Using Ultra-Lightweight Cross Laminated
Timber Floor System, Proc. of International Structural
Engineering and Construction- Emerging Technologies and
Sustainability Principles, 7(2), ISSN: 2644-108X, 2020.
[11] S. Dernayka, D. Ahmed, M. Ajmal, A. Asiz, and T. Ayadat,
Comparison of wind induced response of high-rise buildings
with reinforced concrete and cross laminated timber.
Proceedings of International Structural Engineering and
Construction, 9(1) State-of-the-art Materials and Techniques in
Structural Engineering and Construction, 2022. DOI: 10.14455/
10.14455/ISEC.2022.9(1).STR-21.
[12] S. Lehmann, Sustainable construction for urban infill development
using engineered massive wood panel systems, Sustainability., vol.
4, no. 10, pp. 2707–2742, 2012. DOI: 10.3390/su4102707.
[13] A.B. Robertson, F.C. Lam, and R.J. Cole, A comparative cradle-to-
gate life cycle assessment of mid-rise office-building construction
alternatives: laminated timber or reinforced concrete, Buildings.,
vol. 2, no. 3, pp. 245–270, 2012. DOI: 10.3390/buildings2030245.
[14] J. Salazar, and J. Meil, Prospects for carbon-neutral housing:
the influence of greater wood use on the carbon footprint of a
single-family residence, J. Cleaner Prod., vol. 17, no. 17, pp.
1563–1571, 2009. DOI: 10.1016/j.jclepro.2009.06.006.
[15] M. Popovski, J. Schneider, and M. Schweinsteiger, Lateral load
resistance of cross- laminated wood panels. World Conference
on Timber Engineering, Riva del Garda, Trento, Italy, pp. 20–
24, 2010.
[16] Lintai Wang, Wenxue Gao, and Baoping Sun, Study of dynamic
response of High-Rise buildings under blasting earthquake consid-
ering model simplifying, Mech. Adv. Mater. Struct., vol. 27, no.
24, pp. 2068–2089, 2020. DOI: 10.1080/15376494.2018.1541491.
[17] A. Asiz, and I. Smith, Control of building sway and force flows
using ultra-lightweight slabs, ASCE, J. Perform. Constr. Facil.,
vol. 28, no. 6, A4012015. 2014. DOI: 10.1061/(ASCE)CF.1943-
5509.0000580.
[18] D. Ahmed, and A. Asiz, Structural Performance of Hybrid
Multi-Storey Buildings with Massive Timber-Based Floor
Elements Loaded Under Extreme Loads, Int. J. CMEM., vol. 5,
no. 6, pp. 905–916, 2017. DOI: 10.2495/CMEM-V5-N6-905-916.
[19] Saudi Building Code, National Committee of Saudi Building
Code, Saudi Arabia, 2018.
[20] Eugenia Gasparri, Angelo Lucchini, Gabriele Mantegazza, and
Enrico Sergio Mazzucchelli, Construction management for tall
CLT buildings: from partial to total prefabrication of fac¸ade ele-
ments, Wood Material Science & Engineering., vol. 10, no. 3,
pp. 256–275, 2015. DOI: 10.1080/17480272.2015.1075589.
[21] CSI, ETABS – Integrated Analysis, Design, and Drafting of
Building Systems, Computer and Structure Inc., CA, USA, 2016.
[22] FPinnovation, Canadian CLT Handbook, 2019 Edition Vol I
and II, FPinnovation, Pointe-Claire, Quebec, Canada, 2019.
[23] Michael A. Nisbet, Medgar L. Marceau, and Martha G.
VanGeem, 2002. Environmental Life Cycle Inventory of
Portland Cement Concrete (PDF). National Ready Mixed
8 D. AHMED ET AL.

Concrete Association. PCA R&D Serial No. 2137a. Portland
Cement Association. Archived from the original (PDF) on 6
May 2017. Retrieved 17 April 2021.
[24] McKinsey, Decarbonization of industrial sectors: the next fron-
tier, 2018.
[25] Portland Cement Association (PCA), 2021. https://www.cement.
org/docs/default-source/th-paving-pdfs/sustainability/carbon-
foot-print.pdf.
[26] World Steel Association, 2021. https://worldsteel.org/
[27] A. Younis, and A. Dodoo, Cross-laminated timber for building
construction: a life-cycle-assessment overview, Journal of
Building Engineering., vol. 52, pp. 104482, 2022. DOI: 10.1016/
j.jobe.2022.104482.
[28] Steel ships, 2022. https://www.sustainable-ships.org/stories/2022/
carbon-footprint-steel
[29] I. Tiseo, Carbon footprint of travel per kilometer in the UK
2022, by transportation mode. Statista, 2023. https://www.sta-
tista.com/statistics/1233337/carbon-footprint-of-travel-per-kilo-
meter-by-mode-of-transport-uk/
[30] T. Wang, K. Li, D. Liu, Y. Yang, and D. Wu, Estimating the
carbon emission of construction waste recycling using grey
model and life cycle assessment: a case study of Shanghai,
IJERPH., vol. 19, no. 14, pp. 8507, 2022. DOI: 10.3390/
ijerph19148507.
[31] Y. Chen, Y. Fang, W. Feng, Y. Zhang, and G.X. Zhao, How to
minimise the carbon emission of steel building products from a
cradle-to-site perspective: a systematic review of recent global
research, J. Cleaner Prod., volumevol. 368, pp. 133156, 2022.
DOI: 10.1016/j.jclepro.2022.133156.
[32] B. Huang, Y. Chen, W. Mcdowall, S. T€urkeli, R. Bleischwitz,
and Y. Geng, Embodied GHG emissions of building materials
in Shanghai, J. Clean. Prod., (vol. 210,), pp. 777–785, 2019.
DOI: 10.1016/j.jclepro.2018.11.030.
[33] M. Puettmann, A. Sinha, and I. Ganguly, Life cycle energy and
environmental impacts of cross laminated timber made with
Coastal Douglas-FIR, J Green Build., vol. 14, no. 4, pp. 17–33,
2019. DOI: 10.3992/1943-4618.14.4.17.
MECHANICS OF ADVANCED MATERIALS AND STRUCTURES 9