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Current Journal of Applied Science and Technology
40(45): 7-22, 2021; Article no.CJAST.81454
ISSN: 2457-1024
(Past name: British Journal of Applied Science & Technology, Past ISSN: 2231-0843,
NLM ID: 101664541)
Improving the Building Energy Efficiency and
Thermal Comfort through the Design of Walls in
Compressed Earth Blocks of Agricultural and
Biopolymer Residues Masonry
Etienne Malbila a,b*, Simon Delvoie c, David Toguyeni b,d, Luc Courard c
and Shady Attia e
a Laboratoire d'Energies, Thermiques Renouvelables, (LETRE),Université Joseph KI-ZERBO,
Ouagadougou, Burkina Faso.
b de Fada N'Gourma,Fada, Burkina Faso.
c Laboratoire de Physique et Chimie de l'Environnement (LPCE),Université Joseph KI-ZERBO,
Ouagadougou, Burkina Faso.
d Laboratoire de Matériaux de Construction (LMC),University of Liege, Liege, Belgium.
e Sustainable Building Design Lababoratory, Université de Liege, Liege, Belgium.
Authors’ contributions
This work was carried out in collaboration among all authors. All authors read and approved the final
manuscript.
Article Information
DOI: 10.9734/CJAST/2021/v40i4531624
Open Peer Review History:
This journal follows the Advanced Open Peer Review policy. Identity of the Reviewers, Editor(s) and additional Reviewers,
peer review comments, different versions of the manuscript, comments of the editors, etc are available here:
https://www.sdiarticle5.com/review-history/81454
Received 21 October 2021
Accepted 25 December 2021
Published 27 December 2021
ABSTRACT
Buildings should be assessed in their energy behaviour to identify the most suitable construction
material for the climatic context. This paper studies the influence of construction materials for the
wall in housing hygrothermal behavior and energy efficiency. Three types of construction material
for the wall, which are CSEB of fonio straw and Shea butter cakes, cement blocks, and cut laterite
blocks were selected and the building design was modeled in the DesignBuilder interface. The
thermal comfort and total amount of energy required for building cooling were calculated using
dynamic modelling using EnergyPlus software. The simulation was run according to the
meteorological parameters of Ouagadougou city and we noted that the housing thermal behaviour is
impacted by the wall in earth-based. The results show that the number of warm thermal discomfort
Original Research Article
Malbila et al.; CJAST, 40(45): 7-22, 2021; Article no.CJAST.81454
8
hours and the cooling energy loads are respectively reduced by an average rate of 10.60% and
93.86% in housing with the wall in CSEB of fonio straw and Shea butter residue masonry, in
comparison with the wall in cement or cut laterite blocks masonry. In terms of the indoor
environment, the effect of this wall in earth-based makes it possible to maintain an average internal
temperature and indoor operating temperature respectively at 28.64°C and 25.82°C. The average
indoor temperature peaks damping is achieved to 6.54°C (i.e. 22.83%). It is thus noted that these
CSEB walls are an efficient contribution to sustainable dwelling construction in a hot region.
Keywords: Modelling and simulation; eco-materials; thermal comfort; energy efficiency; housing; hot
region.
NOMENCLATURE
Rt : Thermal resistance (m².K/W)
Rtp : wall global thermal resistance (m².K/W)
e : thickness (m)
hi :internal thermal heat coefficient
(W/m².K)
he :enternal thermal heat coefficient
(W/m².K)
λ : Thermal conductivity in W/m•K
Cp : Specific heat (kJ/kg. K)
ρ : Density in kg/m3
°C : Celsius degree
K : Kelvin degree
T_opm : Average operative temperature (in °C)
U_bat : Overall heat transfer coefficient,
(W.m^(-2).K^(-1))
G : Coefficient of heat loss, (W.m^(-3).K^(-
1))
Acronyms and Abbreviations
A13FF : Clay material mixed with 3% of fonio
straw (N°1)
A23FF : Clay material mixed with 3% of fonio
straw (N°2)
A13RL : Clay material mixed with 3% of Shea
butter cakes
BLT : Cut laterite blocks
BTC : Compressed Earth Blocks
CSEB : Compressed Stabilized Earth Blocks
CV : Split cooling capacity unit
LMC : Laboratory of Construction Materials
STD : Dynamic Thermal Simulation
1. INTRODUCTION
The impact of the built environment on the
climate and the earth's resources is very
important since the construction industry is the
largest user of materials and energy in the world
[1]. The increase in energy consumption in
building design and construction and the issues
related to environmental protection have steered
many current researchers toward examining the
ways to reduce total CO2 emissions, which
resulted in the development of various measures
to increase energy efficiency [2]. The Positive
Energy Building is announced as the contribution
of the construction sector to the solution of the
major problems facing humanity at the beginning
of the 21st century: global warming, depletion of
fossil energy resources, scarcity of raw materials,
and the finiteness of our world in general [3].
Local materials based on earth and natural
resources are gradually giving way to concrete
and its derivatives, which are now the most
widely used building materials in the construction
industry in Burkina Faso. Various considerations
contribute to this and increase the cost of
construction and operation of buildings. Indeed,
the unsuitability of these imported materials with
the climate leads to an increase in energy needs
over the entire life cycle. Sustainable
development is becoming increasingly important
in the construction sector. Therefore, building
techniques that reduce environmental impacts by
minimizing industrial processes and using locally
available materials, such as earth, are receiving
a new impetus [4].
A study on materials used in the building industry
provides a basis for construction projects, but
this must be done to local conditions so that all
parameters are examined for optimal use. In
Burkina Faso, the materials used in the current
construction such as concrete, cement block, are
characterized by poor thermal properties of solar
radiation in hot regions. Instead of local materials
based on natural soil or stabilized with industrial,
forestry, and agricultural by-products [5], [6], [7].
This study is part of this dynamic and focuses on
the use of local build materials in a dry tropical
climate such as that of Burkina Faso. Building
constructed with local material present nowadays
interest in the perspective of sustainable
development [8], as they are better adapted to
the local climate. Implementing walls in adobe or
CSEB is an alternative a sustainable construction
Malbila et al.; CJAST, 40(45): 7-22, 2021; Article no.CJAST.81454
9
[9]. Indeed, the physical properties of local
materials interact with each other and integrate
other variables such as cultural construction
practices and traditional technologies (knowledge
and expertise) to form a coherent construction
set for humans, the environment, and the
climate. Because maintaining the balance
between the human body and its environment is
one of the main requirements for health, safety,
and comfort [10]. And the current development
challenge is based on responsible energy
consumption. The temperature and humidity
present in the building can cause energy
consumption, degradation of building materials,
and a feeling of discomfort for humans [11]. The
management of thermal comfort must meet
several requirements, including technical
requirements. ASHRAE defined Thermal comfort
as that condition of mind which expresses
satisfaction with the thermal environment and is
assessed by subjective evaluation [12] [13]. The
study or the choice of material for a wall is
important because [14] the wall thermal
performance influences housing thermal comfort
and energy consumption. S.H. Moussa et al,
2019 shows that the number of hours of warm
and humid thermal discomfort was impacted for
stabilized CEB based masonry in comparison
with cement-based masonry. [15].
The nature of the building materials is a
significant factor, whether natural or composite.
To achieve sustainable and green technology in
construction, more alternative methods were
produced to replace the conventional
construction materials which lack concern on
elements of sustainability especially on humans,
economics, and the environment [16]. According
to [5], Nere pod stabilization saves on 20 to 43%
energy depending on the mixing rate compared
to laterite and the decrement factor and the time
lag are better when the wall thickness increases
It’s in this context that this research, we highlight
the compare the influence of wall in CSEB with
fonio straw and Shea butter cake, cement blocks,
cut laterite blocks, on the habitat thermal
behaviour. Thus, it’s planned to design a housing
model to determine whether thermal comfort is
achieved; that by varying building walls material
and their thermophysical properties.
2. MATERIALS AND METHODS
2.1 Wall Thermal Performance
Building envelope participates in providing
thermal comfort to users and in the optimal
management building energy consumption [17].
For building envelope thermal performance
study, several physical parameters are to be
considered. It is important to define suitable
descriptive indicators. Indeed, criteria allowing to
evaluate the energy performance are defined,
like Building annual energy performance and
occupants thermal comfort [18]. In this study the
main difference between different walls are the
material, the component and the size. For this
purpose, the thermal resistance of the evaluated
wall are determined by following equation:
2.1.1 Thermal resistance of each material
component (
The thermal resistance (RT) characterizes the
material ability to slow down heat transfer by
conduction. It is calculated with the following
equation:
(1)
With:
, in m2.K/W Thermal resistance ;
e, thickness in m
, thermal conductivity in W/ (m.K).
2.1.2 Wall global thermal resistance (
It characterizes the sum of heat transfer by
conduction within the material and surface heat
exchange by convection and radiation.
, in m2.K/W (2)
Where and are respectively the walls
internal and external thermal resistances.
They characterise the proportion of heat
exchange that takes place at the surface of the
wall by radiation and convection. It depends on
the direction of the heat flow and the orientation
of the wall. The following expressions can be
applied:
et (3)
Where and represnet especively internal
and external surface heat coefficient in w/ (m².k).
In the present study, they are identical for the
different cases studied. So the comparison will
focus on the Σ (e/ λ) component of
equation 2.
Malbila et al.; CJAST, 40(45): 7-22, 2021; Article no.CJAST.81454
10
2.2 Modelling and Simulation
Frameworks
The numerical study consists of the modelling of
a building used for socio-economic housing in
Ouagadougou in Burkina Faso and the
simulation of its energy and hygrothermal
behaviour. Indeed, It‘s subject of wall influence
according to the type of construction material
used. This influence will be established through
the thermal parameters obtained such as
temperature, relative humidity, and the
necessary energy quantity to maintain habitat
thermal comfort. The period considered for this
study is the month of April, which is the hottest
month in the dry tropical climate zone. This study
is completely numerical and we have established
a conceptual framework for a descriptive study of
our working methodology based on [19]. Fig. 1
shows our methodology’s main areas that will be
described in the following paragraph.
2.3 Building Description
Building constructed with local materials is
nowadays of interest in the logic of sustainable
development [8]. According to [20] the ultimate
material efficiency aim is not to use lower
Fig. 1. Study conceptual framework
Fig. 2. Building architectural plans
•Material thermophysical
properties
•Occupancy
scenario+Equipment
•The zone climatic data
Modelling and
simulation Data
•Building modelling
•Outputs
parameters
• Scenario of
simulation
Software
Design
Builder+EnergyPlus •Temperature
•Relative Humidity
• Energy
Consumption
Data collection
and Analysis
Malbila et al.; CJAST, 40(45): 7-22, 2021; Article no.CJAST.81454
11
materials quantity, but to reduce the impacts
associated with their use. Our study aims at
analyzing walls constructed with local composite
materials (earth + natural cakes) impact on
residential building thermal comfort and energy
performances. To minimalize annual energy
consumption, a shorter-term objective is to
design solids baselines on building envelopes
(wall, floors, and roof) [21]. In search of energy
efficiency, it’s possible to investigate the choice
of construction materials, building insulation, and
the optimization of equipment operation. May the
current development challenge be based on
responsible energy consumption?
On an architectural level, the building to be
assessed is a common standard villa type F3
used in the city of Ouagadougou and
characterized by a living area of 56.77m ² as
designed in Fig. 2. For this purpose, the building
will be considered in the dry tropical climatic
conditions of the area of the Ouagadougou
weather database file. The building description is
shown in Fig. 2:
Table 1 presents the properties of the
construction materials used in this study.
The developed soil bricks can be used for
affordable and sustainable housing construction
across the world, particularly in developing
countries [23], [24], [16]. Table 1 shows the
properties of common construction material and
local materials such as the CSEB-A13FF, CSEB-
A23FF, and CEM-A13RL in Fig. 3.
These are local construction materials consisting
of well define mixture of clay and agricultural
cakes and bio-polymer and whose thermo-
physical and mechanical properties are
Table 1. Material thermo-physical properties ( [19], [22]) RT2000 and IEPF 2002
N°
Material description
(W/m. K)
Cp (kJ/kg. K)
(kG/m3)
Thickness
(cm)
1
Air gap(Attic)
0.192
1.00
1.218
62.5
2
Cement block
0,67
880
1250
15
3
Cut laterite block (BLT)
0.85
0.73
1850
15
4
CSEB -A13FF
0.504
1.967
1960
9
5
CSEB -A23FF
0.594
1.967
1904
9
6
Reinforced concrete paving
1.7
0.653
2400
10
7
Cement mortar (plaster)
0.87
1.05
2200
2.5
8
CEM-A13RL plaster
0.737
1.578
2008
2.5
9
False celling plaster
0.11
1.3
400
0.5
10
Floor tile
1.25
1.00
2000
0.7
11
Subfloor
1.21
1.00
1900
5
12
Single and clear glazing
0.96
0.837
2500
0.5
13
Isoplane door
0.12
2.51
593
2.5
14
Sheet metal
828
0.93
2700
0.07
(a) (b) (c) (d)
Fig. 3. (a) CSEB of (b) fonio straw and (c) Shea butter cakes, (d): Cut laterite blocks
Malbila et al.; CJAST, 40(45): 7-22, 2021; Article no.CJAST.81454
12
characterized by [19]. This study will investigate
the influence of these composite materials on the
habitat thermal behaviour and compare them
with cement block and cut laterite blocks (BLT)
walls.
2.4 Choice and Description of the
Simulation Tools
Building simulation software tools are mostly
used by the building designers and engineers to
explore various design alternatives under varying
climatic conditions, internal gains, building
envelope characteristics, building geometry,
heating, ventilation and cooling (HVAC) system
specifications, operation schedules, and control
strategies, etc. [25].
In perspective to reach this study objective, the
comparative approach is used by an analyzing
process based on dynamic energy simulation
with Design Builder tool integrated to Energy+
calculation engine [26] available in Sustainable
Building Design Lab of Liege University. The
building energy and environmental performances
and thermal comfort need reliable dynamic
thermal simulation tools [27]. And the
interface Design Builder/Energy+ allows
us to perform dynamic simulations on the
thermal and energy behaviour of buildings, as
well as to obtain results on energy loads, indoor
thermal environment, and discomfort level.
Emergent energy and environmental questions
related to a building’s thermal comfort and indoor
air quality require accurate knowledge of
temperatures and air movements inside
buildings [21]. For this purpose, the modelled
building is considered a single thermal
zone.
2.5 Simulations Conditions
The simulation conditions considered the
occupancy scenario, the installed equipment
operation, the input data, and thermal comfort
physical parameters. Moreover, the life cycle
analyses showed the importance of the
operational phase in building energy balance
concerning construction and end-of-life phases
[28,29].
In the present study, the building energy and
thermal dynamic simulation were done
considering four (4) person occupancy scenario
and a split system for air conditioning equipment.
The required thermal comfort conditions are
indoor temperature between 26°C and 29°C and
average relative humidity (HR) % of 50%.
A total of four types of walls envelope materials
were studied. The description of building walls
components is presented in Table 2:
The comparative study approach was chosen to
evaluate the thermal and energy performance of
the building constructed with walls in CSEB
formulated by [19] at the Laboratory of
Construction Materials of Liege University in
comparison to other common construction
materials.
The wall’s thermal properties have both great
influences on wall temperature distribution and
heat transfers from the wall [26]. The wall’s
nature-level adaptation is of particular interest in
solar radiation management, creating a barrier
between the inside and outside of a room that
modifies the thermal exchanges. The walls
envelope materials component, their thickness,
color, coating, and thermo-physical properties
are the main factors involved in their evaluation
[10]. Three (03) types of building materials were
selected: cement blocks and cut laterite blocks
(BLT) commonly used and a CSEB composite
material "earth + agricultural cakes and
biopolymer" and the study concerned four (04)
cases of walls envelope.
The characteristics of the roof, openings, and
ground floor are kept identical for all studied
cases. The only variation concerns the walls
envelope, which by the construction materials
used and the number of layers. The envelope
material variants studied are described in Table
3.
This study aims to contribute to local building
materials valuation, given that no one can
progress by ignoring the richness of its heritage.
And by developing a scientific understanding of
traditional know-how we can help to develop new
architectural solutions inspired by tradition [10].
The simulation outputs collected are the indoor
discomfort hour’s number, the air conditioning
energy demand, the indoor, and the average
operating temperature for twelve months. To do
compare results, on focusses of April month.
Indeed, in this region, the most difficult periods
are the maxima of April and June, when a
supplement of artificial air conditioning is
inevitable [30] and April is taken from the hot
period when temperatures are high and humidity
low [31].
Malbila et al.; CJAST, 40(45): 7-22, 2021; Article no.CJAST.81454
13
Table 2. Wall envelope and construction materials descriptions for the case studied
Designation
Base case
Case 1
Case 2
Case 3
Wall
Cement mortar
plaster+Cement
block+Cement
mortar plaster
(=20cm)
BLT
(17.5cm)
CEM-A13RL+CSEB-
A13FF + CEM-A13RL
(19cm)
CEM-
A13RL+CSEB-
A23FF + CEM-
A13RL (19cm)
Roof
Sheet tile (7/10 mm)
Windows
Single clear glazing and metallic frame (5mm) and size 120cm*120 cm et
60cm*60 cm
False ceiling
Plaster false ceiling (5 cm)
Ground
Reinforce concrete paving+ cement mortar+ floor tile(=15.7cm)
Table 3. Synthesis of wall variant layer modelled in Design Builder
Variant
Wall layer description
Outer layer
Main layer
Inner layer
Total thickness(cm)
Base case
Cement mortar
Cement blocks
Cement mortar
20
Case 1
-
Cut laterite block
Cement mortar
17.5
Case 2
CEM-A13RL Mortar
A13FF
CEM-A13RL Mortar
19
Case 3
CEM-A13RL Mortar
A23FF
CEM-A13RL Mortar
19
3. RESULTS
3.1 Wall Construction Material Thermal
Performance
The thermal resistance and heat flow of the walls
are determining factors in the influence of the
wall on the overall thermal behaviour of a
building. These parameters for the three wall
types are summarized in the Table 4 below:
Table 4 shows that the thermal resistances and
heat flows are better for the wall in earth-based
in comparison to the other walls i.e. walls in
cement blocks and cut laterite blocks. Indeed the
gain in thermal flow for the wall in earth-based is
respectively 33.58% and 70.67% in comparison
to cement blocks wall and cut laterite
blocks.
3.2 Indoor Temperature Evolution during
the Hot Period
Building thermal response depends on the
design, chosen construction materials, and
operating conditions. This study focuses on the
influence of construction materials for walls on
housing indoor temperature evolution.
Below Figs. 4 to 7 give modelled building interior
temperatures evolution profile for each case of
wall envelope studied.
Table 4. Comparison of wall construction material thermal performance
Enveloppe type
Wall
component
RT of each
component
(m².K/W)
RT of the
wall
(m².K/W)
Up W/
(m².K)
φ
(kW)
Cement blocks
masonry
Cement
Mortar
0.0287
0.230
4.35
6.492
Blocks
0.172
Cement
Mortar
0.029
CSEB masonry
Motar
0.034
0.323
3.10
4.312
Blocks
0.255
Motar
0.034
Cut laterite blocks
masonry
Blocks
0.206
0.206
4.86
8.9
Malbila et al.; CJAST, 40(45): 7-22, 2021; Article no.CJAST.81454
14
Fig. 4. Indoor temperature evolution profiles in habitat with cement blocks wall (Base case)
Fig. 5. Indoor temperature evolution profiles in habitat with BLT Wall (case 1)
Below Figs. 8 and 9 present indoor temperature
evolution about ambient temperature respectively
over 10 days and 24 hours during April month.
Fig. 8 presents the comparison of indoor
temperature evolution profiles for walls
cases studied and in relation with ambient
temperature over 10 days during April month of
reference year in dry tropical climate
condition.
Fig. 9 presents the comparison of indoor
temperature evolution profiles for the walls cases
studied and about ambient temperature over 24
hours during the day of 7th April in dry tropical
climate conditions.
The curves on all figures describe identical
indoor temperature evolution profiles whatever
the type of building wall construction materials
used. The average indoor temperature is
Malbila et al.; CJAST, 40(45): 7-22, 2021; Article no.CJAST.81454
15
between 28.52°C to 28.91°C and is lower than
ambient temperature. This indicates that all walls
construction materials used allow for building
indoor temperature peaks dumping during
considered period, especially during heat period.
Then, the average percentage of temperature
dumping over the considered period is 23.28%,
21.67%, 23.32%, and 22.35% respectively for
the base case, variants 1 to 3 studied.
Fig. 6. Indoor temperature evolution profiles in habitat with BTC-A13FF Wall (Case 2)
Fig. 7. Indoor temperature evolution profiles in habitat with BTC-A23FF Wall (Case3)
Malbila et al.; CJAST, 40(45): 7-22, 2021; Article no.CJAST.81454
16
Fig. 8. Comparison of Indoor temperature evolution in relation with external temperature for all
wall cases studied (from 4-9th April)
Fig. 9. Indoor temperature evolution in relation with ambient temperature over 24 hours
3.3 Discomfort Hours Evaluation in
Building
Thermal comfort is a complex notion defined as
the occupant satisfaction sense and which
depends on several physical and physiologic
parameters. For physical parameters,
temperature and relative humidity are used to
appreciate and evaluate the level of thermal
comfort according to the climatic conditions. The
simulation over the year allows us to evaluate the
number of thermal discomfort hours as shown in
below Fig. 10.
Malbila et al.; CJAST, 40(45): 7-22, 2021; Article no.CJAST.81454
17
Basecase Case 1 Case 2 Case 3
0
500
1000
1500
2000
2500
Numbers of incomfort hours
Type of wall studied
Numbers of incomfort hours
Fig. 10. Building indoor discomfort hours about wall construction materials
Fig. 11. Building indoor discomfort hours decrease rate in relation with wall construction
material
Fig. 10 shows the number of building’s indoor
discomfort hours as a function of the type of
envelope wall. From this graph and depending
on the wall construction material, the number of
building thermal discomfort hours is higher when
the envelope wall construction materials are
cement blocks (Base case) or cut laterite
blocks(Case 1) than Compressed stabilized earth
blocks(Case 2 and 3).
Fig. 11 presents the building’s indoor warm
thermal discomfort hours decrease rate in the
four cases studied. As shown in Figure 11, the
number of warm thermal discomfort hours is
lower for walls in earth-based i.e. with CSEB-
A13FF or CSEB-23FF, and coated with
composite earth material (CEM-A13RL)
masonry. These walls in earth-based reduce the
number of warm discomfort hours in housing
0
5.96
-12.19
-9.02
-14
-12
-10
-8
-6
-4
-2
0
2
4
6
8
Basecase
Case 1
Case 2
Case 3
reduction %
Type of wall studied
Taux de reduction(en %)
Malbila et al.; CJAST, 40(45): 7-22, 2021; Article no.CJAST.81454
18
Basecase Case 1 Case 2 Case 3
0
1000
2000
3000
4000
5000
6000
7000
8000
Cooling energy needs (in Wh/m²)
Type of wall studied
Cooling energy needs (in Wh/m²)
Fig. 12. Building cooling energy needs in relation to wall construction materials
from 9.02% to 12.19% compared to walls in
cement-based material.
3.4 Cooling Energy Requirement in
Building
Fig. 12 presents the building air conditioning
(AC) quantity requirement graph in the four
cases of wall construction materials studied.
As shown in Fig. 12 graph, the building cooling
energy demand is lower in cases 2 and 3 which
walls are constructed with CSEB-A13FF and
CSEB-23FF and coated with composite earth
material (CEM-A13RL). The cooling energy
needs are estimated at 94.95wh/m²,
300.51Wh/m², 3223.12Wh/m², and
8104.56Wh/m² respectively for cases 2, 3, and
base case and case 1.
4. DISCUSSION
4.1 Summary of Main Findings
The building thermal and energy behavior were
studied in two stages by modelling the habitat on
Design Builder and then the simulation of
different cases of envelope wall by integrating
Energy Plus. The simulation outputs collected
are the indoor discomfort hour’s number, the air
conditioning energy demand, the indoor, and the
average operating temperature. Table 5
summarizes the values obtained for each
envelope wall variant studied.
Table 5 shows that operative temperature
(25.71°C-25.95°C), cooling energy needs (94.95
- 300.51 Wh/m²), and the discomfort hour’s
number (2186.50-2265.50 hours) are lower in
building modelled with CSEB walls than cement
or cut laterite blocks walls. Therefore, based on
these three selected criteria, the Building thermal
and energy behavior is better with walls variants
2 and 3 i.e. in wall in earth-based. By keeping
housing other constant parameters, we noticed
that the envelope construction materials choice is
important in building energy and thermal comfort
performance search.
The analysis of the results indicates an average
reduction of 10.60% of the warm thermal
discomfort hours and 93.86% in thermal loads
with an average operating temperature between
25.71°C and 25.92°C when using CSEB to fonio
straw with coatings of CEM with 3% Shea butter
cakes. Moreover, the indoor temperatures are
between 28.52°C and 28.91°C (Figs. 8 and 9),
i.e. an average difference of 0.16°C to 0.39°C
from variant 3 to the base case. These operating
and indoor temperatures are below those of the
building constructed either in cement or cut
laterite blocks. This performance of building
stabilized soil material was observed by [32] who
find that the thermal performance coefficients
Ubat and G are lower in earthen constructions
(adobe, BTC, BLT) than in modern constructions
(cement block). However, the results obtained
can be reinforced by complementary options in
terms of roof type, building orientation, and
openings.
Malbila et al.; CJAST, 40(45): 7-22, 2021; Article no.CJAST.81454
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Table 5. Synthesis of energy and thermal simulation results
Variant
Number of discomfort hours
Cooling energy needs
(in hour)
Decrease %
(in Wh/m²)
Decrease %
(in °C)
Base case
2490
-
3223.12
-
25.95
Case 1
2638.50
+5.96
8104.56
+151.45
26.25
Case 2
2186.50
-12. 19
94.95
-97.05
25.71
Case 3
2265.50
-09.02
300.51
-90.67
25.92
This local eco-materials option permit therefore
in line to meet having internal temperatures with
the Ouagadougou building thermal comfort zone
(26-30°C), obtained by [33] through the use of
insulation materials such as cotton and straw
coupled with BLT giving temperatures between
28.7°C to 30.5°C for cotton, and 29.8°C to 31°C
for straw. Thus, the present study results
increase the scientific knowledge on CSEB with
natural local resources and their potential
impacts on building’s thermal and energetic
performance. This could contribute to Burkina
Faso and other UEMOA (West African Economic
and Monetary Union) country governments for
the integration political of building energy
efficiency requirements code in their area [34].
Indeed, building with earth materials has many
advantages, such as its availability and required
thermo-physicals and thermal properties in
habitat construction, cost reduction, and
environmental impacts reduced by minimizing
industrial processes [4].
4.2 Strength and Limitations
We studied the wall envelope influence on
building thermal and energetic global behavior.
The study results show that earth material
improved with fonio straw and Shea butter cakes
contribute to better thermal comfort et reduce
energy consumption in the habitat. It appears
that:
the walls in Compressed earth blocks
stabilized with fonio straw (CSEB-A13FF or
CSEB-A23FF) and coated by composite
shea butter cake and earth material (CEM-
A13RL formulated by [19] offer good average
interior and operating temperatures;
the number of discomfort hours and the
energy requirements for air conditioning is
reduced;
the choice of the type of envelope
construction materials is very decisive in the
search of the thermal comfort achievement;
These results contribute to the valuation of local
building materials in the hot region but this study
remains in a numerical study by simulation case
and does not take into account:
recent meteorological data of the study area ;
separately the building different pieces.
4.3 Implication on Practice and Research
The results obtained show that the building
industry can rely on the use of local building
materials to address the duality of thermal
comfort and energy consumption search the hot
region context. For example, sustainability
guidelines for energy and carbon emissions
suggest that we need to halve our energy use
from 2000 to 2050 [35] [36]. In this context, it’s
essential to reduce housing operating
temperature and construction materials
production energy used.
In the use of research prospects, we will be
interested in:
In-situ instrumentation of housing built with
wall envelope in Compressed earth blocks
stabilized with fonio straw (CSEB-A13FF
or CSEB-A23FF) and coated by
composite shea butter cake and earth
material (CEM-A13RL) ;
CSEB-A13FF/CSEB-A23 and CEM-A13RL
adhesion characterization when used for
composite wall envelope. The presence of
the rendering is important and its hold on
the wall structure must be perfect. For the
rehabilitation of old houses, the coating of
aerogel-based rendering considerably
reduces energy consumption [37].
In-situ CEM-A13RL coating durability and
repellency characterization on an existing
building in adverse weather conditions.
5. CONCLUSION
The best way for the construction industry is to
explore the use of natural and industrial
secondary resources to provide new materials for
sustainable construction. The choice of building
Malbila et al.; CJAST, 40(45): 7-22, 2021; Article no.CJAST.81454
20
materials is determined by their properties, cost,
and accessibility. This paper deals with the
influence of the local materials for walls on
housing behavior by numerical study. Then the
comparative study concern three types of
construction material for wall, that are
compressed earth block, cut laterite blocks, and
cement blocks. The results indicate that walls in
Compressed earth blocks stabilized with
agricultural cakes (fonio straw) and bio-polymer
(Shea butter cake or residue) give the housing
advantageous thermal comfort and energy
consumption compared to walls in cement or cut
laterite blocks. More specifically, the main
conclusion can be drawn:
The wall in earth-based material (CSEB) offer
the reduction by 10.60% of the warm thermal
discomfort hours in housing;
The wall in earth-based material (CSEB) offer
a reduction by 93.86% in thermal loads with
an average operating temperature between
25.71°C and 25.92°C.
Indeed, by using this wall in local composite
material, the housing indoor temperature remains
within the limits prescribed for dry tropical
climates thermal comfort, with a significant
reduction of discomfort hour’s number and air
conditioning energy requirements. Then, the
compressed stabilized earth blocks of fonio straw
and Shea butter cakes presents an
environmentally sustainable alternative that
avoids the use of energy-intensive during the
building life cycle. This study highlights the
influence of local eco-materials on housing
thermal behavior and its contribution to building
energy efficiency.
ACKNOWLEDGEMENTS
This study was conducted as part of the
SERAMA program for Secondary Resources
valuation for Sustainable Construction. This
research was completely founded by the
“Academie de Recherche et d’Enseignement
Supérieur (ARES)”in Laboratory of Construction
Materials (LMC) and in Sustainable Building
Design Lab Liege University. The author would
like to acknowledge the support of the Institute of
Environmental Engineering and Sustainable
Development (IGEDD) of the University Joseph
KI-ZERBO during the project submission
COMPETING INTERESTS
Authors have declared that no competing
interests exist.
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