Experimental and TRNSYS-Based Assessment of Bio-Based Reinforced Plaster for Sustainable Building Applications

Abstract

This investigation aims to experimentally evaluate the thermal performance of plasters reinforced with bio-based materials and to assess their contribution to sustainable construction and the reduction in the environmental footprint of building materials by simulating their impact on the thermal behavior of a building in different Moroccan climates using TRNSYS software. Three types of samples were investigated: pure plaster and two others strengthened by 4% of alfa fibers and 6% of coffee grounds. Each model was produced with the following different water-to-plaster ratios (W/P): 0.5, 0.6, and 0.7. The results demonstrated that the inclusion of aggregates and the increase in water content improved the thermal qualities of the composites. A combination of 4% alfa fibers and a W/P ratio of 0.7 significantly reduced thermal conductivity by 32.24%, decreased density by 26.82%, and lowered the decrement factor by 21.67%. Additionally, a composite containing 6% coffee grounds and a W/P ratio of 0.7 demonstrated a reduction in thermal amplitude by 15.61% and decreases in both thermal conductivity and density by 26.05% and 22.23%, respectively. Dynamic simulation indicated that these designs reduced greenhouse gas emissions and energy loads. However, energy gains using optimal configurations were considerable and similar in the following locations: Agadir (16.3%), Tangier (14%), Meknes (13.5%), Ifrane (13.42%), Marrakech (13.6%), and Er-rachidia (12.5%).

1. Introduction

1.1. Statement of the Problem

The persistent interaction between the building and its external conditions constitutes a modern research topic that presents many challenges in the framework of sustainable development and energy efficiency [1]. Demographic growth and the improvement in comfort technologies have increased the energy usage of the housing sector to the levels of the transport and industry segments. It represents 20 to 40% of worldwide final energy consumption [2], thus contributing largely to climate change and air pollution issues [3]. For this reason, much attention has been paid to the guaranteed preservation of the environment and the progressive reduction in energy intake [4,5,6]. The design of an efficient and sustainable envelope is therefore an essential element to promote from the beginning of the construction process. It is indispensable to establish the required heating and cooling loads and correlate them to thermal losses through the building envelope [7,8]. Insulation appears to be one of the effective solutions to mitigate and to attenuate thermal exchanges via the walls, but its use increases production costs [9]. However, the development of a fast, passive and economic technique has become of crucial importance in the energy conservation field. In this regard, special interest has been granted to the manufacture of new eco-composites formed by additives and classical materials [10,11,12].

1.2. State of Art

1.2.1. Composite Materials: A Step Towards Sustainability

Depending on their availability, their cost, their ecological aspect, and their thermal qualities, several aggregates can be coupled with building materials to produce alternative bio-composites. Indeed, in recent years, the use of natural fibers as additives presents many attractive advantages that favor their potential exploitation over others [13,14]. They are generally renewable, bio-degradable and, above all, accessible, as they are the main source of income for the population in rural areas [15]. They also offer a beneficial impact on environmental safety [16,17]. On the other hand, the high global waste production rate (about 1.3 billion tons per year) creates multiple ecological problems [18,19]. Hence, the integration of waste into materials is one possible solution to overcome this challenge and is currently becoming as interesting as reinforcements in the construction sector [20,21,22].

Basically, the choice of the reinforcing material depends on its compatibility with the main matrix and its desired intrinsic properties. Hence, additives such as Typha Australis, glass powder, olive kernels, and coconut fibers have been employed to improve the thermo-physical characteristics of several cementitious materials [23,24,25,26]. They offer them the possibility of insulating and delaying heat transmission [27]. In addition, other sorts of aggregates like waste plastics, rubber tire ashes and date palm fibers have been used to produce composites with particular mechanical qualities [28,29,30]. Therefore, the sought advantages include reducing density, maintaining a good resistance to bending and compression, bringing in the effects of ductility, and lowering the cracking problems. It is also worth mentioning that several additives possess the ability to improve the acoustic characteristics of materials such as wood particles [31]. Usually, the combination of all tests is further used to identify the best-performing composites on all levels [32].

1.2.2. Plaster-Based Composites

Over the years, plaster has proven to be one of the preferred conventional materials in construction applications. It was used by many researchers as the main matrix to encapsulate additive matters to improve some of its thermo-mechanical and ecological properties. This material results from the firing of gypsum, and its mixing with water allows the production of porous solid pieces with a disordered texture [33].

It is used in construction for renders or prefabricated elements due to its thermal and acoustic properties, fire resistance, aesthetic qualities, and low cost [34,35]. It is also characterized by a low thermal expansion coefficient (1.2 × 10⁻⁴–2.0 × 10⁻⁴ K⁻¹) [36]. Its thermal properties are also defined by a thermal conductivity of about 0.526 W/m.K and a thermal diffusivity of 3.45 × 10⁻⁷ m²/s [37]. Nevertheless, despite its favorable appreciation compared to other cementitious materials, plaster remains relatively unsatisfactory regarding the requirements of thermal regulations [38]. Therefore, knowledge of plaster morphology and the improvement in its properties become necessary.

Several researchers have been interested in developing certain plaster matrix properties. Mutuk et al. [39] examined the possibility of combining gypsum with natural fibers such as hemp and banana fibers. This approach provided an effective solution for developing green bio-composites. At the microscopic level, the addition of these fibers increased the porosity within the matrix structure. As a result, the thermal conductivity and the thermal load were decreased, improving the insulation performance of the composite. A formulation containing 5 wt% of hemp–banana fibers achieved a thermal conductivity of 0.131 W/m.K compared to 0.237 W/m.K for pure gypsum.

In the same framework, Cuce et al. [40] developed a new composite based on plaster modified with hazelnut shell particles, intended for building envelope applications. The progressive incorporation of these additives induced a remarkable improvement in thermal performance compared to the reference material. Additionally, increasing the incorporation rate from 2% to 6% led to a continuous reduction in U-value, from 2.40 to 2.04 W/m².K, along with a low thermal conductivity ranging between 0.0408 and 0.0486 W/m.K. Also, Rachidi et al. [41] investigated the thermo-physical properties of a new construction composite made with plaster and wood shavings. This represents a modern alternative technique to manufacturing more efficient coating plasters aiming at improving the building thermal envelope. Indeed, the results obtained showed that the developed composite materials presented very good insulation quality. However, the thermal conductivity decreased from 0.252 W/m.K to 0.099 W/m.K as the wood shaving content increased from 5% to 15%, reflecting an improvement in insulation performance.

1.2.3. General Background on Alfa Fibers and Coffee Grounds

In order to create a link between the basic framework of this research and the main materials that will be employed in the experiment, this state-of-the-art technique is also intended to provide some general knowledge on the alfa fibers and coffee grounds used as reinforcing substances for the plaster. Stipa tenacissima L. (usually named alfa) is a perennial plant that belongs to the grass family. It is an Asian-origin herb currently endemic to the western Mediterranean. Its native steppes mainly stretch through the North African countries, particularly in Algeria, where it covers an area of about 4.5 million hectares [42].

As an abandoned material with attractive sustainable characteristics, alfa fibers have also been the subject of several studies aiming to discover the possibility of integrating them in the approach of developing new bio-composites. In this context, Maaloufa et al. [43] examined the influence of a fibrous reinforcement on the thermal and mechanical properties of plaster. They discovered that 29% of the alfa admixture significantly improved the thermal conductivity and diffusivity, with a gain of 56 and 29%, respectively. As a result, the composites achieved excellent thermal inertia. Another study based on the use of the same matrix was carried out by Lachheb et al. [44]. The authors examined the impact of alfa fibers on the thermal properties of a plaster matrix. The acquired results indicated a considerable reduction in thermal conductivity from 0.5 to 0.227 W/m.K by increasing the concentration of aggregates to 4%.

Alfa fiber has also been treated as a reinforcement to modify some physical properties of cementitious materials. Sakami et al. [45] developed a new preparation process to produce mortar samples reinforced with a fiber fraction varying between 0 and 5%. The highest dosage allowed them to reduce the composite density by 15% and to upgrade its thermal insulation capacities by 57% compared to the reference material. It is important to highlight that the compressive and flexural resistance was improved by 10% with a 1% proportion of the fibers. However, beyond this fraction, the mechanical performance started to decline. But, a good combination of thermo-mechanical properties could bring out a very interesting composite to be used in construction in the Mediterranean region.

Regarding the coffee grounds, these are presented as a solid powder resulting from the infusion process of coffee beans by means of steam or hot water. Over the last few years, the coffee industry has grown gradually, and its product is now considered the second most traded commodity in the world after petroleum [46]. Worldwide, according to the International Organization, coffee consumption has reached approximately 9.91 million tons. This allows the production of more than 6 million tons of coffee ground waste per year [47]. However, due to their polysaccharide aspect, high-burning capacity, and significant dump cost, these residues are proving to be undesirable for compost and landfilling [48]. Several recycling methods for coffee grounds are appearing currently, such as their use as a health-supporting product or an alternative fuel resource [49,50]. In addition, attention has focused on its potential adoption in civil engineering applications.

In this respect, Manni et al. [51] conducted a deep analysis on a composite formed by clay and coffee waste. Firing was carried out at a temperature of 1150 °C in order to obtain a strong densification of the samples. However, it was noticed that these experimental conditions offered excellent dimensional stability along with better aggregate compatibility. Indeed, the findings indicated that the use of 30% coffee particles in the main matrix permitted the achievement of a good combination between its porosity (42.81%) and its density (1.46 g/cm³). Moreover, its thermal conductivity was also reduced by about 53.42%. Similarly, Velasco et al. [52] evaluated the effect of coffee grounds on the thermo-mechanical properties of clay-based brick. The experiments indicated that these organic substances burn simultaneously within the matrix during the firing phase without generating structural deformations. On the other hand, the authors advised against the application of high aggregate concentrations, as they increase the water absorption rate and reduce the mechanical characteristics of the matrix. However, a percentage of 17% of waste was concluded as the optimal proportion since it allowed the authors to obtain composites with excellent thermal conductivity (0.36 W/m.K).

1.3. Aim of This Study

The current study represents a continuation of two previous research works conducted by Touil et al. [53,54]. The prior investigations focused on the analysis of the thermo-mechanical properties of plaster reinforced with either alfa fibers or coffee grounds. Specifically, alfa fibers were incorporated in random form at proportions of 1, 2, 3, and 4% by mass, while spent coffee grounds were introduced in granular form at 2, 4, and 6%. All formulations were prepared using three water-to-plaster (W/P) ratios: 0.5, 0.6, and 0.7. The upper limits of additive content were defined by practical constraints related to workability, as higher dosages significantly hinder the mixing process of the composites.

The main outcomes of these previous studies, summarized in Figure 1, highlight the evolution of thermal conductivity and flexural strength as a function of additive content. The results clearly demonstrate that increasing both the additive percentage and the W/P ratio significantly enhance the thermal performance of the plaster. For instance, thermal conductivity decreased from 0.44 W/m.K for pure plaster to approximately 0.252 W/m.K with 4% alfa fibers at a W/P ratio of 0.7, and to about 0.289 W/m.K with 6% coffee grounds at the same ratio. However, this improvement in thermal insulation is accompanied by a reduction in mechanical performance. The flexural strength decreased from 5.79 MPa for pure plaster to approximately 2.18 MPa (4% alfa fibers, W/P = 0.7) and 2.12 MPa (6% coffee grounds, W/P = 0.7). Despite this reduction, the obtained values remain above the minimum thresholds required by the standard EN 13279 [55] (Figure 1), confirming the mechanical suitability of these composites for building applications.

Based on these findings, the composites incorporating the highest additive content and W/P ratio were selected as the most promising candidates for thermal insulation applications in buildings. Nevertheless, the previous studies were primarily limited to the characterization of thermo-mechanical properties at the material scale. The novelty of the present work lies in moving beyond this initial characterization toward a comprehensive and multi-scale analysis of the selected optimal composites. In this context, the current study introduces several contributions:

• A detailed experimental investigation of advanced thermal performance indicators, including time lag and decrement factor, which are essential for evaluating dynamic thermal behavior.
• The establishment of drying kinetic profiles to better understand curing mechanisms.
• An in-depth microstructural analysis to understand the relationship between porosity and thermal behavior.
• A numerical model through the simulation of a building incorporating the optimized composites within its envelope using TRNSYS software under different Moroccan climatic conditions.
• An environmental assessment of the developed composites, aiming to evaluate their contribution to reducing the environmental footprint.

2. Materials and Methods

2.1. Raw Materials

2.1.1. Natural Additives

The alfa fiber used in this experimental research was extracted from the Stippa tenacissima plant. This raw material was collected from the vicinity of Oujda City, Morocco, where it exists in a considerable quantity despite being abandoned. This grass is presented in the form of a cylindrical ribbon, with an average length of about 1.6 m [56]. Before being exploited, the alfa fibers were exposed to high-pressure water in order to remove the dust sticking to their surfaces and to eliminate all undesired particles. Subsequently, they were naturally dried at room temperature for 2 days. Afterwards, the strip extremities were cut and were the objective of selective sorting to homogenize their diameters all along their length. Finally, the uniform fibers were separated and slashed to a length between 5 and 30 mm (Figure 2a), and then stored in a drying oven at a temperature of 24 °C until the beginning of sample preparation.

Concerning the spent coffee grounds, these were collected from different coffee shops in Meknes, Morocco. Generally, this material is widely available because of its massive consumption. Indeed, it is present as a granular powder of which the granular pore volume comprises between 0.02 and 0.07 cm³/g, while its specific surface ranges from 0.305 to 0.88 m²/g [57]. Since these substances are usually mixed with other residues such as milk boxes and food waste, they must undergo a separation and cleaning process before being exploited. Afterwards, the obtained texture was crushed to homogenize the particle size. Then, it was scrubbed with distilled water and dried in a drying oven at a temperature of 105 °C for 24 h to remove its moisture, following the EN 14774-1 standard [58]. Lastly, the final material (Figure 2b) was also stored in a dry place until sample formulation.

By observing their morphological aspects under the scanning electron microscope (SEM) (Figure 3 and Figure 4), it appears that both materials contain an important quantity of oxygen (O) and carbon (C) elements, with the existence of considerable zinc (Zn) and calcium (Ca) percentages in the composition of the coffee grounds. The microstructure of the alfa fibers indicates that they are composed of several filaments orderly distributed along the fiber and their average diameter is around 500 μm. Meanwhile, the coffee particles are characterized by many micro-pores, and their average size is approximately in the order of 200 μm. In addition, the surface structure of both matters is rough, wrinkled, and irregular. Therefore, this is a positive sign for their potential adhesion with building materials. In addition, the alfa fibers and coffee beans have an average density of 211 and 419 Kg/m³ and a thermal conductivity of 0.041 and 0.161 W/m.K, respectively (

Table 1. Physical properties of the additives used.

Additive	Thermal Conductivity (W/m.K)	Density (kg/m3)
Alfa fibers	0.041 ± 2.1 × 10−4	211 ± 0.45
Coffee grounds	0.165 ± 2.1 × 10−4	419 ± 0.312

). These valuable properties will certainly modify the sensitivity of the construction matrix to conduct heat.

2.1.2. Binder

In order to valorize the country’s local resources, a commercial plaster-based product was used in this investigation. This material (${\mathrm{CaSO}}_4·{\displaystyle \frac{1}{2}}{\mathrm{H}}_2\mathrm{O}$) is present as a powder (Figure 5a) and manufactured from natural rocks located near the City of Safi, Morocco. It contains a high content of hydrated $\beta$-hemihydrate due to the calcination of calcium sulfate. It is widely employed in construction applications such as wall covering and false ceilings thanks to its aesthetic and thermal insulation properties, as well as its good fire resistance. The elemental analysis of its particles identified the dominant existence of carbon (C), calcium (Ca), silicon (Si) and sulfur (S) (Figure 5b). However, the detailed chemical composition of plaster is illustrated in

Table 2. The chemical composition of the used plaster in [%]. Reprinted from Touil et al. [59], “An experimental investigation of the water blending rate effect on the plaster’s thermo-mechanical properties,” AIP Conference Proceedings, 2023, with the permission of AIP Publishing.

SiO2	R2O3	CaO	MgO	Na2O + K2O	SO3	H2O	CO2 and Volatiles
0.46	0.17	37.61	0.12	0.03	53.66	6.16	1.59

.

2.2. Design and Mixing Protocol

Three series of plasters were produced with three water-to-plaster ratios (0.5, 0.6, and 0.7). Each series consists of three configurations: a pure matrix, a composite reinforced with 4% alfa fibers, and another incorporating 6% coffee grounds. The choice of these water ratios aims to evaluate the influence of mixing water content on the thermal behavior of the samples. In this regard, the ratio of 0.7 is considered as a standard consistency for plaster preparation, while 0.5 corresponds to a relatively dry mixture and 0.6 represents an intermediate state [54]. This selection is justified by the fact that water content is a key parameter affecting the morphology, porosity, and microstructure of plaster, and consequently, its thermo-physical properties. In addition, the selected additive dosages are based on previous experimental studies conducted by Touil et al. [53,54] (see Section 1.3).

Table 3. Formulation details of plaster-based composites and additive contents.

Plaster Content (%)	Additive Content (%)	W/P Ratio	Sample
100	0	0.5	PL/0.5
		0.6	PL/0.6
		0.7	PL/0.7
96	4 (Alfa fibers)	0.5	APAF/4/0.5
		0.6	APAF/4/0.6
		0.7	APAF/4/0.7
94	6 (Coffee grounds)	0.5	PCG/6/0.5
		0.6	PCG/6/0.6
		0.7	PCG/6/0.7

presents the nomenclature, mixing ratios, and additive percentages for each configuration.

The preparation procedure of the specimens’ paste differed from one composite to another depending on the used additive. The experimental protocol of the fabrication was carried out at laboratory-room temperature as follows:

• For the formulation of pure plasters, the powder was carefully and gradually added to the water in a bucket to allow complete contact between the two substances.
• Regarding the composites based on alfa fibers, the natural aggregates were first blended with the necessary amount of water and the mixture was left to rest for 2 min. Then, the plaster powder was also sprinkled slowly with a good distribution on the water surface to enable a better adhesion of the fibers within the container.
• Concerning the plaster samples reinforced with coffee grounds, the manufacturing process was different. Initially, the appropriate quantities of the plaster powder and the coffee granules were mixed in their dry state to obtain a homogeneous texture. Then, the latter was gradually sprinkled into the water in the same way as the previous composites.

However, it is necessary to mention that the three model mixtures were manually blended only once and slowly, which could last only up to 3 min, to avoid the rapid setting of the plaster. Afterward, they were transferred into cleaned molds to maintain the appropriate geometry and dimensions for the experiments. After one hour, they were demolded and dried in an oven at a temperature of 50 ± 1 °C to eliminate any trace of moisture. Finally, the developed parts were kept in a dry place until the experimental tests were performed after 28 days (Figure 6). For each studied model, three samples with the dimensions of 25 × 25 × 4 cm³ were considered for thermal behavior characterization.

2.3. Thermal Experiments

2.3.1. Thermal Tester

The characterization of the composites’ conductivity and thermal behavior was assessed using a highly insulated house of 40 × 40 × 40 cm³ (Figure 7) [60]. It has a cover, insulated by a 5 cm thick Styrofoam plate, that can be fixed to the base support by means of four screws. Moreover, its special geometry contains four openings of 21 × 21 cm² in each side wall to isolate the studied material or multilayer structure by additional substances, or to put them in complete contact with the external air. However, the samples of 25 × 25 × 4 cm³ must be placed inside the house on one lateral wall, while maintaining the others shuttered by polystyrene panels and heavy wood, to minimize heat losses.

The thermal regulation of the indoor heating is supplied by a 100 W light lamp. It is associated to a thermal control panel that allows the adjustment of the inward air temperature up to a 60 °C limit. In addition, this electrical unit is enclosed by a black box to reduce radiation effects. Eight thermocouples (Type K) for temperature measurements were investigated. Three probes were utilized to record the temperature of the sample’s inner surface (T₁, T₂, and T₃), and three others to measure the outer temperature side (T₄, T₅, and T₆), and the remaining two (T₇ and T₈) were used to determine the temperature of the box’s inside air and the ambient atmosphere, respectively. However, the interior probes were inserted into the house through the holes on its vertical corner edges. Finally, the data acquisition upgrade was performed using a Hilton data logger, and the display of the measurements was accomplished using Windows-compatible controlled software.

2.3.2. Thermal Conductivity Measurement

The thermal conductivity was obtained using a standard protocol with an uncertainty of less than 10%. However, measurement of the involved temperatures within the energy balance ($T_2$, $T_5$, $T_7$ and $T_8$) was done with an acquisition time step of 5 s, and the reading was carried out after reaching a steady state (about 6 h). Afterward, an average value for each probe over a period of 30 min was established and utilized for the calculation process [61]. Moreover, it should be mentioned that the surface contact sensors ($T_2$ and $T_5$) should be applied in the middle of the samples’ lateral sides to ensure a reliable distribution of the generated heat flux and to minimize the temperature gradient effects between these two measurement points. The thermal conductivity was calculated through Fourier’s law (Equation (1)).

$$\begin{array}{c}{\left({\displaystyle \frac{\varphi }{S}}\right)}_m=\lambda {\displaystyle \frac{(T_2-T_5)}{e}}\end{array}$$

(1)

where the ${\left({\displaystyle \frac{\varphi }{S}}\right)}_m$ ratio is the experimental mean value, estimated from the expressions (2) and (3), which represent the convective heat transfer between the air and the inner and outer walls of the sample, respectively. In addition, $h_{int}$ and $h_{ext}$ are the heat exchange coefficients. They have a value of 8.1 W/m²K, as recommended for the case of natural air movement in enclosed rooms [62].

$$\begin{array}{c}{\left({\displaystyle \frac{\varphi }{S}}\right)}_{int}=h_{int}(T_7-T_2)\end{array}$$

(2)

$$\begin{array}{c}{\left({\displaystyle \frac{\varphi }{S}}\right)}_{ext}=h_{ext}(T_5-T_8)\end{array}$$

(3)

2.3.3. Thermal Behavior Characterization

The objective of this part is to characterize and to compare the thermal performance parameters of the developed composites such as their insulation properties, the time lag, and the decrement factor.

Indeed, the insulation quality represents the ability of a material to prevent heat transmission through its structure over time. The operating mode of this investigation was performed by exposing the sample’s internal surface to an 80 W heat flux. First, its outer face was in direct contact with ambient air, which was preserved at a temperature of approximately 20 °C by means of an air conditioner. The measured values ($T_{ext}$/$T_5$) of the external thermocouple were recorded from the beginning of the experiment until obtaining steady state in order to identify the temperature trend for each studied composite. Later on, the configuration that required more time to maintain the thermal equilibrium was determined.

Furthermore, the other two characteristics are essential parameters used to define the thermal profile of a construction material under specific temperature conditions. Indeed, the time lag ($T{L}_{\varphi }$) refers to the time needed for thermal excitation to propagate from the sample’s inner to outer surface. It is calculated graphically via the time interval that occurs between the two peak temperatures of the two faces (Equation (4)). As for the decrement factor (f), it is described as a reduction ratio of the amplitude of the external side temperature $D_{ext}$ to the internal one $D_{int}$ (Equation (5)). Figure 8 shows a graphical representation of these two thermal properties. The determination method of these two qualities was carried out by exposing the inner faces of the composites to three periodic thermal excitation cycles of 80 W, maintained continuously for 90 min each. A period of 180 min must elapse between two successive excitation cycles. The external ($T_{ext}$/$T_5$) and internal ($T_{int}$/$T_2$) temperatures were thus recorded and used for calculation purposes.

$$\begin{array}{c}T{L}_{\varphi }=T_{int\_max}-T_{ext\_max}\end{array}$$

(4)

$$\begin{array}{c}f={\displaystyle \frac{D_{ext}}{D_{int}}}={\displaystyle \frac{T_{ext\_max}-T_{ext\_min}}{T_{int\_max}-T_{int\_min}}}\end{array}$$

(5)

3. Results and Discussion

3.1. Experimental Analysis

3.1.1. Microstructure Analysis of the Samples

The microstructure assessment is a crucial process in order to establish the link between the thermo-mechanical properties and the structural morphology of the developed materials. Indeed, Figure 9a, Figure 9b, and Figure 9c highlight the surface sections of PL/0.5, PL/0.6, and PL/0.7, respectively, under the scanning electron microscope. However, the main remark extracted from this analysis illustrates the impact of raising the mixing water ratio on the increase in the crystallization degree of the plaster particles. It was found that the exploitation of a water-rich consistency allows the generation of crystals in the form of randomly oriented needles. As a consequence, this induces the appearance of several pores that will certainly affect the thermal and mechanical qualities of the plaster later on. In contrast, a drier consistency is characterized by a lack of crystallization content validated by the existence of non-hydrated granules, as well as a low rate of porosity.

Similarly, Figure 10a and Figure 10b represent the cross sections of the APAF/4/0.7 and PCG/6/0.7 designs, respectively. Indeed, the first pattern shows an excellent adhesion of the fibers within the plaster, along with the presence of some holes at the contact surface between the additive and the binder. Therefore, this will allow the increase in the porosity rate of the composite compared to the pure plaster. Moreover, this behavior will contribute to a weakening of the bond between these two substances and reduce the mechanical performance at high dosage levels. On the other hand, it is obvious that coffee grounds are also compatible powdery materials with the plaster-based matrix and induce considerable porosity within the structure of this composition. In addition, the existence of several plaster particles that cover the coffee granules demonstrates the good homogeneity and the adhesion degree between these two materials.

Based on these observations, it can be noted that the porosity of the composites is strongly influenced by both the water content and the additive percentage. Increasing these parameters leads to a higher porosity rate, which is a key factor contributing to the reduction in mechanical strength, as discussed in Section 1.3. This increase in void content weakens the cohesion within the matrix and reduces its load-bearing capacity. On the other hand, this process positively affects the thermal performance, as the pores tend to encapsulate air, a material well known for its low thermal conductivity, thereby enhancing the insulating properties of the composites. This effect is further amplified by the intrinsic thermal insulating characteristics of the bio-based additives, which contribute to an overall improvement in thermal efficiency (Section 3.1.3).

From another perspective, similar structure property relationships have been reported in calcium-based materials, where the evolution of the internal structure, whether crystalline or gel-like, is governed by ionic interactions and controls porosity, connectivity, and mechanical performance [63]. In particular, studies at the atomistic scale have shown that modifications in calcium-related interactions can significantly influence structural organization and pore development, thereby affecting macroscopic properties. Although the present system is based on gypsum, which forms a crystalline network rather than a gel structure, these findings support the interpretation that changes in structural connectivity and porosity are key factors governing the observed mechanical and thermal behavior.

3.1.2. Drying Profile and Isothermicity

In order to follow the drying strategy and to control the water content present within the various studied materials, a measuring process of the samples’ mass loss was carried out. For this purpose, several typical pieces (6 × 4 × 4 cm³) formulated in the same way as the main specimens were prepared (Figure 11a). These models were weighed once before their introduction in the oven (Figure 11b). Then, for each hour of time, a typical model was taken and weighed using an electronic balance with a precision of ±0.001 g. The experiment was stopped when two successive measurements of mass had the same value. The reason for applying this operation was to minimize the heat exchange effects between the drying oven and the environment and to follow the approximate curing kinetic profile of the composites without affecting the temperature and humidity conditions imposed during the main samples’ drying process.

Figure 12 shows the weight loss of all studied configurations over time. From the graph analysis, it is observed that the stabilization of the sample mass begins after approximately 10 h from the start of the experiment. However, this stabilization does not occur simultaneously for all materials. The pure plaster samples reach equilibrium earlier, typically between 10 and 12 h, whereas the composites exhibit a delayed stabilization depending on the type of additive.

In terms of additive incorporation, it is evident that introducing aggregates into the plaster matrix increases both the water content and the time required to achieve complete drying. More specifically, the composites reinforced with alfa fibers show the highest mass losses for all levels of the water-to-plaster ratio. This indicates that the fibrous reinforcement has a higher water absorption capacity compared to the granular material. Furthermore, considering the W/P ratio, the samples prepared with the highest consistency (0.7) require longer drying times and exhibit greater mass losses. This confirms that the setting and drying behavior of plaster is strongly influenced by the amount of mixing water. In addition, the composites produced with optimal mixing and reinforcement ratios (APAF/4/0.7 and PCG/6/0.7) demonstrate the highest water absorption capacities and require extended drying periods. Unlike the pure samples, their mass stabilization is reached at later times, around 18 to 20 h, with final mass losses of approximately 43.8% and 41.8%, respectively.

In order to validate the samples’ homogeneity, an isothermicity verification process was performed. To proceed, three thermocouples were placed on each material surface ($T_1$/$T_2$/$T_3$ and $T_4$/$T_5$/$T_6$), as shown in Figure 13, and then a power of 80 W was applied inside the thermal tester. The temperatures were recorded after reaching steady state.

According to the results presented in

Table 4. Measured temperatures at different points of the samples’ faces in [°C].

Measurement Side	Tint in the Final State			Text in the Final State
Measuring Point	T1	T2	T3	T4	T5	T6
PL/0.5	39.987 ± 0.027	39.997 ± 0.023	39.967 ± 0.02	32.337 ± 0.025	32.347 ± 0.027	32.467 ± 0.028
PL/0.6	40.757 ± 0.021	40.557 ± 0.029	40.707 ± 0.021	32.377 ± 0.033	32.187 ± 0.035	32.387 ± 0.026
PL/0.7	40.887 ± 0.022	40.777 ± 0.019	40.737 ± 0.023	32.147 ± 0.031	31.977 ± 0.025	32.117 ± 0.034
APAF/4/0.5	41.957 ± 0.082	41.727 ± 0.068	41.197 ± 0.054	33.217 ± 0.046	32.977 ± 0.025	32.607 ± 0.061
APAF/4/0.6	41.367 ± 0.052	41.947 ± 0.049	41.497 ± 0.074	32.127 ± 0.065	31.507 ± 0.071	32.137 ± 0.106
APAF/4/0.7	41.947 ± 0.084	42.217 ± 0.081	41.567 ± 0.079	32.967 ± 0.11	33.067 ± 0.71	32.827 ± 0.112
PCG/6/0.5	40.187 ± 0.036	40.197 ± 0.052	40.287 ± 0.0679	31.437 ± 0.067	31.037 ± 0.056	31.307 ± 0.048
PCG/6/0.6	40.83 ± 0.074	40.727 ± 0.081	40.357 ± 0.079	31.597 ± 0.107	31.327 ± 0.83	31.477 ± 0.052
PCG6/0.7	41.517 ± 0.042	41.367 ± 0.039	41.247 ± 0.045	32.637 ± 0.061	32.477 ± 0.049	32.487 ± 0.071

, it was found that the surfaces of pure plaster materials (PL/0.5, PL/0.6 and PL/0.7) are more isothermal. In contrast, the other two configurations show a greater difference between the temperatures measured on each side. This indicates that the incorporation of additives into the plaster matrix leads to a relative loss of the composites’ homogeneity. Furthermore, by comparing the two types of structures, it appears that the nature and the shape of the aggregates are the main causes that determine the isothermicity degree. However, the coffee particles, which have an approximately uniform size at the macroscopic scale, provide the materials with more homogeneity than the alfa fibers. Generally, since the difference between the temperature distribution of the two surfaces of each tested substance does not exceed 0.8 °C, homogeneity at the macroscopic level is ensured, and the method of sample preparation is further approved. In addition, this also validates the exploitation of low additive concentrations in the reinforcement of building materials.

3.1.3. Evaluation of the Thermo-Physical Properties

The identification of the thermo-physical properties is an essential process to characterize the density and insulating capacity of porous materials and to provide an overview of their suitability for construction applications. In fact,

Table 5. Measured thermo-physical properties.

Configuration	Parameters	$\mathit{\rho }$ in [kg/m3]	$\mathit{\lambda }$ in [W/m.K]
			Current Study	Using the Box Method
PL/0.5	Mean	1398.4	0.415	0.443 [53]
	STDV	11.04	0.00197	0.00225
PL/0.6	Mean	1368.2	0.402	0.392 [54]
	STDV	9.31	0.00174	0.0027
PL/0.7	Mean	1172.2	0.384	0.372 [53]
	STDV	7.83	0.00341	0.00227
APAF/4/0.5	Mean	1281.2	0.317	0.308 [53]
	STDV	12.09	0.00083	0.00102
APAF/4/0.6	Mean	1092.1	0.305	0.298
	STDV	10.62	0.00266	0.00154
APAF/4/0.7	Mean	1023.3	0.281	0.252 [53]
	STDV	11.04	0.00209	0.00353
PCG/6/0.5	Mean	1314.8	0.368	0.349 [54]
	STDV	3.31	0.00219	0.0004
PCG/6/0.6	Mean	1202.34	0.324	0.315 [54]
	STDV	5.62	0.00321	0.0015
PCG/6/0.7	Mean	1087.5	0.294	0.289 [54]
	STDV	4.41	0.00175	0.0006

presents the density and thermal conductivity results of the various investigated samples. The experimental findings determined in this work are in good agreement with those obtained using the box method [53]. This indicates the reliability of the exploited test methodology.

Based on these outcomes, it can be seen that there are some major changes within the specimens due to the effects of additives and the mixing water rate, as shown below:

• In the case of materials made with an identical W/P rate, the thermo-physical characteristics decrease with the transition from a simple matrix to a compound one. As an example, for the category produced with a standard consistency (W/P of 0.7), the plaster density drops from 1172.2 to 1023.3 kg/m³ when using alfa fibers, and to 1087.5 kg/m³ by employing coffee grounds. The same remark can be projected on the thermal conductivity evolution. It decreases from 0.384 to 0.281 and 0.307 W/m.K when utilizing the fibrous reinforcement and the coffee particles, respectively.
• The level of water used for the samples’ preparation also appears to be an interesting influential element during aggregate addition. Thus, its increase enabled the improvement in the thermal conductivity and density for all types of composites.
• The combination of these two actions allowed the production of more insulating and less heavy pieces. However, APAF/4/0.7 and PCG/6/0.7 are considered as the configurations with the best thermo-physical properties, exhibiting significant reduction rates of 32.24 and 26.05% for thermal conductivity and 26.82 and 22.23% for density, respectively.

The causality relationship between the studied influencing parameters and the induced effects can be explained through the samples’ microstructure. Indeed, as already validated by the microscopic tests, the presence of a large mixing water amount during the composites’ preparation improves the crystallization degree, and subsequently provokes the creation of several pores within their structure. However, the propagation of air within this porous network, which has low thermal conductivity (0.026 W/m.K) [64], permits delaying thermal transfers. Furthermore, the fibers of alfa and coffee grounds have thermal conductivities of approximately 0.041 and 0.161 W/m.K, respectively. Therefore, their existence allows a further reduction in the composites’ sensitivity to heat transmission. Moreover, the same observations can be projected on the samples’ density. In fact, the low density of the coffee particles and the alfa fibers compared to the plaster bulk density causes an extreme diminution of the latter. This effect becomes more important with the rise of the voids within the plaster structure shouted by high water dosages.

To ensure the conformity of the acquired results, a bibliographical study was carried out on some identical research works. Laoubi et al. [65] demonstrated that the incorporation of polystyrene beads into the plaster matrix can produce appreciable modifications to its thermal profile. However, they noticed that an aggregate content of 50% can lead to a decrease in the bulk density by about 56.7%, as well as a thermal conductivity below 0.2 W/m.K. In addition, referring to the work of Gutiérrez González et al. [66], the observations related to the influence of the W/P ratio were validated. The authors indicated that the progressive rise of the mixing water content can significantly reduce the density and thermal conductivity of plaster- and polyurethane-based composites by up to 60 and 66%, respectively. Touil et al. [53] observed that the combined increase in the blending rate and alfa fibers allowed the acquisition of an interesting optimal decrease of 43.11% in the thermal conductivity and 46.04% in the apparent density, while respecting the appropriate mechanical standards. Overall, all these investigations are in good agreement with the composite microstructure analysis. Therefore, they confirm that raising the water content permits a better crystallization of the plaster particles, which increases the sample porosity, while the insertion of additives improves the heat insulation characteristics.

3.1.4. Assessment of the Heat Delay Capacity

The thermal retardation property of building materials depends strongly on their thermo-physical characteristics. Therefore, the incorporation of additives with an insulating aspect in their matrices allows an improvement in their thermal behavior. However, the thermal response of the external surface is translated into a transient and a steady-state part. The duration of the first phase depends on the composition of the tested specimen. The histograms presented in the Figure 14 permit a clarification of the required time for each configuration to attain their equilibrium temperature under the same conditions.

In fact, the heat propagation delay through the materials is more expressive with the samples that need more time to achieve thermal stability. Thus, the samples APAF/4/0.7 and PCG/6/0.7 required higher approximate times of 336 and 319 min to reach steady state, respectively. In addition, the effect of increasing the mixing water content was also noticeable. However, by switching from a dry consistency to a standard one, it was possible to further delay the transient phase by approximately 27 min for the pure plasters, by 25 min for the coffee particle-reinforced plasters, and by 34 min for the alfa fiber-based plaster composites. It can also be concluded that the latter is more sensitive to the blending water rate used. The results obtained can be explained by the insulation capacity level, which is determined by the composite thermal properties. Nevertheless, high thermal resistance and low density can improve the thermal inertia and delay the heat propagation within the plaster. Overall, the new composites prepared with the maximum additive dosages and mixing ratios of 0.7 can be considered as promising construction materials that are capable of stabilizing the building’s interior temperature.

3.1.5. Thermal Performance Evaluation

Along with its insulation characteristics, the thermal performance of a building envelope must also be evaluated through two key dynamic indicators, namely the decrement factor and the time lag. In real conditions, the thermal behavior of a building envelope is governed by daily climatic variations, where the outdoor temperature increases during the day and decreases at night, inducing a delayed response in the indoor temperature. This coupled evolution defines the dynamic thermal performance over a 24 h cycle.

In the present study, the adopted periodic heating strategy is designed as a controlled representation of this dynamic mechanism, reproducing the fundamental processes of heat propagation and thermal inertia within the material. By applying cyclic thermal excitation with a period of 180 min and maintaining a well-defined temperature gradient (Section 2.3.1), the method enables a precise characterization of phase shift and attenuation effects governing the material response while ensuring strict control of boundary conditions. Furthermore, the use of a reduced thermal cycle (180 min) allows the generation of multiple successive cycles, thereby enhancing the repeatability and statistical reliability of the measurements. This accelerated approach provides a consistent framework for comparing different formulations under identical conditions while preserving the fundamental physics of transient heat transfer. Thus, Figure 15 illustrates a representative example of the external and internal temperature evolution under the applied periodic regime.

Based on the results obtained, the incorporation of additives inside the plaster reduces the decrement factor compared to pure matrices (Figure 16). However, the benefit is in favor of the models prepared with mixing ratios of 0.7. A decrease of 4.15% was noted for neat plasters, and a significant diminution of approximately 9.75% was observed for plasters reinforced with coffee particles. Otherwise, the composites based on alfa fibers showed the greatest behavior. They allowed the amortization of the thermal amplitude by more than 12.42%. Furthermore, it is worth highlighting that the APAF/4/0.7 and PCG/6/0.7 configurations are considered the most suitable materials since they enabled the achievement of an optimal gain in decrement factors up to 21.67 and 15.61%, respectively, compared to the PL/0.5 model.

Moreover, the increase in the thermal phase shift degree is more significant to describe the thermal behavior of a material over time (Figure 17).

The parallel rise of aggregates and mixing water content contributed favorably to improving the time lag. However, as in the case of the decrement factor, the best enhancements were more expressive in the models prepared with the maximum rate of additives and blending water. Thus, it was possible to obtain gains of 675.5 and 555.5 s using alfa fibers and coffee grounds, respectively.

In order to establish a concrete relationship between the thermal performance characteristics and the thermal conduction property, a graphical representation was created that shows the evolution of the time lag and the decrement factor as a function of thermal conductivity (Figure 18). Generally, it appears that the increase in the conductivity induces a decrease in the phase shift and causes the rise of the decrement factor. Moreover, the alfa fibers are favorably compared to the coffee particles. This demonstrates the reliability of this fibrous reinforcement, which indicates excellent efficiency. It allows a better delay of heat transmission thanks to its morphology, which gives it a more insulating aspect.

In addition, these results can always be tuned to the analysis of the microstructure presented in Section 3.1.1. This thereby implies that the effects of the additives and mixing ratio determine the thermal sensitivity of plaster matrices. It should also be noted that these findings are in good agreement with the scientific literature. Kahandawa Arachchi et al. [67] evaluated the performance of plaster boards with bottom ash. It was shown that this configuration induces a similar effect to the one presented in this study. Therefore, the inclusion of 60% substances allows a diminishment of the decrement factor by about 20% and increases the time lag by 54% compared to the conventional material. Also, Flores-Alés et al. [68] examined the thermal behavior of mortar blocks based on recycled glass aggregates. The authors demonstrated that a dosage of a 50% addition can offer the possibility of reducing the thermal transmission of a wall by 22%, lowering the decrement factor by nearly 10% and raising the time lag by approximately one hour.

Overall, the obtained results highlight the effectiveness of the proposed materials in improving the thermal behavior of the building envelope under controlled conditions. However, it is worth mentioning that this approach, based on characterization and monitoring, can also be extended toward data-driven analysis, which can be useful for real-time monitoring, providing complementary perspectives and improving the reliability of performance analysis at the real scale. The continuous monitoring of environmental and thermal data through the integration of multi-source monitoring systems, combining temperature measurements with other environmental parameters, allows a dynamic evaluation of system behavior and supports early warning and performance assessment under varying operating conditions [69,70].

3.2. Building’s Dynamic Simulation

3.2.1. Simulation Methodology

Dynamic thermal simulation is a general process that will allow the authors to test the building behavior and to highlight the necessary actions to optimize its design regarding the heating and cooling requirements and occupant comfort. However, with respect to the topic treated in this article, the objective is to validate the thermal performance of the composites developed in a real building composition through deep modeling under TRNSYS software. Figure 19 shows the loop system used to accomplish this process.

Experimentally, the APAF/4/0.7 and PCG/6/0.7 models were specified as the substances presenting the best thermal properties and benefits. For this reason, they were chosen as the optimal configurations to be integrated in a high floor of the simulated building. Although the structure containing the PL/0.7 material was defined as a reference composition since this plaster was manufactured with a standard consistency, it also represents the same mixing ratio as the selected composites. Generally, the evaluation of the dynamic simulation presented was based on three main points: the evaluation of the envelope thermal response according to different Moroccan climates, the identification of the necessary heating and cooling loads, and the determination of the avoided GHG emission rate.

The transient modeling and approximation of the studied physical model were performed in TRNSYS using Type 56 (TRNBuild) based on the energy balance equations described in “Multizone Building Modeling with Type 56” [71].

The boundary conditions used for the numerical simulations were defined based on the climatic data of the studied regions (Figure 20) and the indoor setpoint temperatures (20 °C for heating and 26 °C for cooling). In addition, the characteristics of the building envelope (

Table 6. Basic composition of the building construction.

Element	Construction Material	Thickness in [cm]	Thermal Conductivity in [W/m.K]	Density in [kg/m3]	Transmission Coefficient in [W/m2.K]
Exterior walls	Cement mortar	2	1.15	2500	1.319
	Hollow brick	7	0.807	918
	Air blade	10	0.113	1
	Hollow brick	7	0.807	918
	Cement mortar	2	1.15	2500
High floor	Tile	1	1.3	2300	With PL/0.7
	screed	2	0.42	1800	1.620
	Concrete	4	2.3	2350
	Slab	16	0.6	1000	With APAF/4/0.7
	PL/0.7	4	0.384	1172.2	1.498
	Or, APAF/4/0.7	4	0.281	1023.3
	Or, PCG/6/0.7	4	0.307	1087.5	PCG/6/0.7
	Cement mortar	2	1.15	2500	1.543
Low floor	Tile	1	1.3	2300	3.033
	screed	2	0.42	1800
	Cement mortar	7	1.15	2500
	Concrete	10	2.3	2350

) were taken into account. These properties were obtained under controlled conditions, and in real applications, factors such as moisture and aging may affect the effective thermal conductivity. Moreover, the assumptions adopted for the simulation included an initial temperature and humidity of 20 °C and 50%, respectively. Additionally, the infiltration rate was set at 0.6 ACH, and the internal gains were summarized to a PC with a power of 230 W and an incandescent lamp of 10 W/m². Although the simulation process was generated with a time step of 1 h, these parameters were implemented within the simulation loop (Figure 19) to simulate the corresponding configurations.

The chosen type of construction is widespread in all the regions of Morocco. The building studied consists of a single area with four sides and oriented to the south. It has a floor area of 80 m², and its ceiling height is 3.2 m. It is also equipped with two simple glass windows (U = 5.27 W/m².°C and Surface = 1.8 m²), where one is placed on the east face and the other on the west one. The entrance door is made of wood and has an area of 3.4 m², and its transmission coefficient is 3.3 W/m².K. Table 6 shows the basic composition of the building materials. The plaster on a high floor will be replaced by the models, whether PL/0.7, APAF/4/0.7 or PCG/6/0.7, to meet the objective of the simulation.

3.2.2. Overview of the Various Investigated Moroccan Climates

Due to its geographical position in the north-west of Africa, Morocco is surrounded by two climatic extremes, one being temperate in the north and the other tropical in the south. This has allowed it to have different meteorological conditions along its territory, classified into six major sections. Figure 20 shows the monthly evolution of global solar irradiation and temperatures observed for each studied city.

However, through its analysis, it is possible to come out with the following findings:

• Zone 1, represented by the city of Agadir, benefits from a mild Mediterranean climate. The winter periods seem to be sunny, and the summer ones are agreeably warm. Nevertheless, the maximum solar irradiation is noted during the months of July and August, with 222 and 225 kWh/m², respectively. The average temperature varies between 14 °C in January and 25 °C in August.
• The climate of zone 2 (Tangier) is identical to the one observed in region 1. But, a greater irradiation during the summer can reach up to 234 kWh/m² and brings warmer days. Generally, the average temperature seems softer (around 25 °C).
• The climate of zone 3 (Meknes) shows an intermediate state between the Mediterranean conditions and those of the interior thanks to its fairly high altitude (about 546 m). It is characterized, then, by its hot and dry aspect. In fact, during the year, the mean temperature varies between 10 and 26 °C. The maximum irradiation is 232 kWh/m², noted in August.
• As for zone 4 (Ifrane), it has an elevated altitude that reaches over 1644 m. Therefore, it is distinguished by mountainous weather, where minimum temperatures can be severe during the winter months compared to other areas. Otherwise, the summer period seems to be fresher. The maximum and minimum temperatures thus observed are nearer to 41.2 and −3.3 °C, respectively.
• The effect of the semi-arid interior climate allows the cold Atlantic current to be attenuated and exposes zone 5 (Marrakech) to a very extreme level of irradiation, which subsequently brings very hot summer periods. The peak temperature can exceed 45 °C, while the median temperature can reach 29 °C in August.
• The climate of zone 6 (Er Rachidia) is deserted and hot. However, the radiation intensities received are very high compared to other zones. The maximum temperature reaches about 43 °C in the summer.

3.2.3. Analysis of the Dynamic Thermal Behavior

In order to assess the performance of the selected composites to maintain a more reliable indoor temperature, a thermal analysis was carried out on two days of the year when the meteorological conditions are different. 20 January and 29 July were defined, then, as typical winter and summer periods, respectively. Moreover, the process was generalized on all climatic zones of concern to the present study. Figure 21, Figure 22, Figure 23, Figure 24, Figure 25 and Figure 26 show the evolution of the building’s interior temperature through the various investigated high-floor configurations.

By analyzing the curves, it appears that both green floors behaved thermally in the same way, with a slight advantage of the alfa fiber-based structure at most times. When the outdoor temperature is at its maximum level during the day, the average gain observed by the two configurations compared to the reference reaches about 0.43 °C in the investigated representative cities. On the other hand, in the case of the minimum outside temperature, the amplitude noted is relatively slight. It thus attains a mean value of 0.045 °C in zones 2, 3, 4 and 5. Meanwhile, it is more significant in the regions of 1 and 6, where it achieves 0.25 and 0.19 °C, respectively. For the summer period, the solar irradiation is more intense, which leads to a considerable increase in the building’s indoor temperature. Nevertheless, unlike the winter day, the exterior temperature attenuation becomes more significant for both configurations containing alfa fiber and coffee grounds. However, in comparison to the reference conception, the decreased amplitude is at its maximum during the highest outside temperature. Thus, it reaches an approximate average of 0.71 and 0.83 °C in the cities of Agadir and Marrakech, respectively. In contrast, it achieves a median value of 0.48 °C in the other regions. In addition, when the ambient temperature is at its minimum, an average reduction of 0.3 °C is demonstrated in all climatic zones.

Figure 27 represents the winter and summer decrement factors for the six concerned climate regions. In fact, this element was calculated from the temperature evolution expressed above. Its analysis proves the strong applicability of the APAF/4/0.7 and PCG/6/0.7 models in the high-floor composition. Also, the first one showed a slight advantage due to its better thermo-physical properties. Actually, both composites allowed the authors to significantly reduce this coefficient according to the configuration containing the pure plaster (PL/0.7) in all various zones, independently of the meteorological conditions. In addition, comparing each city by using the same construction structure, the damping factor was greater in the summer period and relatively average in the wintertime. But, in contrast, this behavior was different in the case of Ifrane, where it was at its peak during the cold season. This disparity is due to the high-altitude effect that exposes this region to a mountainous climate where temperatures can be very low. Therefore, this led to a considerable difference in temperature amplitudes between the building’s exterior and interior, whereas the combinations reinforced with bio-based materials favored the maximization of this phenomenon.

The configurations containing APAF/4/0.7 and PCG/6/0.7 behave approximately in a similar way. The decrement coefficient for these two combinations was reduced during winter by about 23.45, 20.9, 17, 33, 19.45 and 23.6% in zones 1, 2, 3, 4, 5 and 6, respectively, compared to the reference. On the other hand, in the summer, it was decreased by nearly 20.3, 20, 19.7, 28.8, 18.2 and 25.3% in regions 1, 2, 3, 4, 5 and 6, respectively. The reinforced plaster shows better performance in hot and cold climates, and worse performance in temperate ones. This highlights its ability to reduce heat transfer and maintain good passive comfort.

3.2.4. Analysis of Heating/Cooling Requirements and Avoided GHG

One of the main objectives of bio-composite materials is to reduce the electrical energy consumed by heating and air conditioning systems. The expected energy savings were calculated based on setpoint temperatures of 20 °C for heating and 26 °C for cooling. Figure 28 presents the annual energy consumption across different climate zones.

By analyzing the results, it seems that the maximum demand appears in the cities of Ifrane and Er-rachidia, while the minimum is found in Agadir city. The requirement is very elevated in these areas since the cooling and heating charges are higher in zones 6 and 4, respectively. In zone 5, the sunshine is very intense during the summer season. Hence, it stipulates significant air conditioning. In contrast, zones 2 and 3 present intermediary values where the energy loads are balanced. This difference can be explained by the particular climatic conditions in each region. In all zones, the annual requirements are well reduced using the APAF/4/0.7 and PCG/6/0.7 models compared to the reference building. Even though both configurations represent approximately the same performance, the alfa fiber-based floor appears slightly better in terms of the provided energy savings. Both structures reflect an identical effectiveness in decreasing the energy consumption. It decreased on average by about 16.3% for Agadir, 14% for Tangier, 13.5% for Meknes, 13.42% for Ifrane, 13.6% for Marrakech and 12.5% for Er-rachidia. Also, by comparing these results with the Thermal Regulation of Construction in Morocco (RTCM), it appears that the annual energy needs in all studied areas exceed the required thresholds, as the buildings are not insulated. However, the use of the proposed green configurations would allow these buildings to approach these requirements, leading to energy savings and helping to optimize insulation thickness.

Considering the environmental aspect, the analysis of the buildings’ energy performance occupies an essential place in the debates of the ecological stakes, notably the excessive emissions of greenhouse gases (GHG). These are the main sources of climate change. In Morocco, the net anthropogenic releases of GHG have been estimated at 100.55 million tCO₂eq [72], from which the energy sector produces about 57% of it. Hence, this requires the application of an efficient strategy to face this problem. The calculation of the GHG rate depends on the type of fuel source used and the intensity of the transmitted gas. In this study, the heating and cooling demands were assumed to be supplied by a reversible electrical heat pump system capable of providing both heating in winter and cooling in summer. The thermal loads were converted into electrical consumption using the performance coefficients of the system, with a coefficient of performance (COP) of 3.35 for heating and 3.0 for cooling. The resulting greenhouse gas emissions were then estimated using an emission factor of $\beta =$ 0.734 kgCO₂eq/kWh, representative of the electricity system [73]. The corresponding calculation method is presented in Equation (6).

$$\begin{array}{c}{M}_{GHG}=\left({\displaystyle \frac{Q_H}{CO{P}_H}}+{\displaystyle \frac{Q_C}{CO{P}_C}}\right)\times \beta \end{array}$$

(6)

where

• M_GHG is the total rate of GHG emitted in kgCO₂eq/year;
• Q_H is the annual heating demand of the building, expressed in kWh/year;
• Q_C is the annual cooling demand of the building, expressed in kWh/year;

Table 7. Annual GHG for different green floor configurations in various meteorological conditions.

Configuration	M(GHG) (PL/0.7)	M(GHG) (APAF/4/0.7)	M(GHG) (PCG/6/0.7)	Avoided GHG Rate in [%]
	in [kgCO2eq/Year]			Using APAF/4/0.7	Using PCG/6/0.7
Z1: Agadir	964.4	803.9	814.5	16.63	15.35
Z2: Tangier	974.7	814.13	824.8	16.47	15.37
Z3: Meknes	1987.9	1715.7	1734.3	13.69	12.75
Z4: Ifrane	3338.7	2877.2	2910.3	13.82	12.83
Z5: Marrakech	2345.2	2022.4	2046	13.76	12.75
Z6: Er-rachidia	3166.8	2771.6	2801.3	12.48	11.54

depicts the annual GHG per unit area calculated for different green floor configurations, as well as the gains produced compared to the reference. From the outcomes obtained, it was found that the implementation of composites within the building structure significantly reduced the rate of emissions. Nevertheless, the one containing alfa fibers appears to be more effective than the one incorporating coffee grounds. Using the PCG/6/0.7 model, the decrease reached 149.82 for Agadir, 149.89 for Tangier, 253.6 for Meknes, 428.3 for Ifrane, 299.2 for Marrakech and 365.5 kgCO₂eq/year for Er-rachidia. On the other hand, with the APAF/4/0.7 model, the gain recorded was around 160.4 for Agadir, 160.59 for Tangier, 272.18 for Meknes, 461.4 for Ifrane, 322.7 for Marrakech and 395.2 kgCO₂eq/year for Er-rachidia. These findings demonstrate the potential of the investigated composite materials to maintain a more ecological environment.

Overall, the evaluation of energy consumption and greenhouse gas emissions confirms that alfa fibers and coffee grounds improved the insulating behavior of plaster, enhancing energy efficiency and reducing environmental impact.

4. Conclusions

This study deals with the valorization of alfa fibers and coffee grounds in the plaster industry. It aims to experimentally evaluate the thermal behavior of these composites and their applicability in buildings. Three types of plaster were investigated: a pure matrix, and two composites reinforced with alfa fibers and coffee particles, produced with water-to-plaster ratios of 0.5, 0.6, and 0.7. The main findings are summarized as follows:

• According to the microstructure analysis, the incorporation of the admixtures increased the porosity of the composites. In addition, the increase in water content promoted the crystallization of plaster particles, further enhancing porosity.
• The results showed that increasing the water content and additives improved the thermal behavior. In terms of performance, APAF/4/0.7 reduced thermal conductivity by 32.24% and density by 26.82%, while decreasing the decrement factor by 21.67% and achieving a time lag of 675.5 s. The PCG/6/0.7 composition also showed significant improvements, with a thermal amplitude reduction of 15.61%, a time lag of 555.5 s, and reductions in thermal conductivity and density by 26.05% and 22.23%, respectively.
• The integration of the optimal composites into the building delayed heat transfer in all climatic zones. In addition, the use of these bio-composites reduced heating and cooling loads, leading to the following notable energy savings: 16.3% (Agadir), 14% (Tangier), 13.5% (Meknes), 13.42% (Ifrane), 13.6% (Marrakech), and 12.5% (Er-rachidia).
• The use of PCG/6/0.7 resulted in GHG emission reductions ranging from about 11.54% to 15.37%, depending on the climatic conditions. The APAF/4/0.7 model showed even greater performance, with reductions varying between 12.48% and 16.63%.

In conclusion, the approaches adopted in this study highlight the potential use of these composites in construction as an effective solution to improve building energy efficiency and reduce greenhouse gas emissions. Future work will focus on the hygric behavior of these materials, particularly through the evaluation of their moisture buffer value (MBV), sorption characteristics, and vapor transfer properties under controlled conditions, to better understand their performance under varying environmental conditions.