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Composite roof layers (a) photo for Isogam installation (b) concrete layers (c) gypsum boards.

Composite roof layers (a) photo for Isogam installation (b) concrete layers (c) gypsum boards.

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Article
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The current study experimentally investigates the optimal thickness of a phase change material (PCM) layer incorporated composite roof under severe exterior temperatures. Three PCM thicknesses, namely 10, 15 and 20 mm, are embedded inside a popular roof combination for residential buildings in Iraq compared with the reference roof without PCM. The...

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... increased cooling loads [20]. The standard Isogam layer (0.4 mm thickness and 10 m long) composed of bitumen-rubber mastic and laminated from both sides with thin plastic layers. One of the layers coated with light-silver colour to reflect the fallen solar radiation and the other is melted by fire to stuck on the concrete roof during installation (Fig. 2a). The reflective layer is removable and highly influenced by changeable weather conditions, limiting its reflectivity after a short term of installation. Therefore, Isogam with removed reflective layer is used in the present work in order to test the PCM thermal behaviour at high exterior surface temperatures, which is the core of the ...
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... according to mixing ratio 1:2:3 of the raw materials (cement: sand: gravel) that is popular used for residential building roofs in Iraq, providing compressive strength 25-30 Mpa [21,22]. The raw materials were mixed with water to fabricate the concrete mixture, which then poured into moulds and left dried naturally to form the concrete layers (Fig. 2b). (iii) Gypsum board (cladding layer): Pre-fabricated gypsum boards (8 mm thickness) were used in this work. Boards are made from gypsum (6 mm thickness) and laminated by thin carton sheets (1 mm) from both sides for strengthening. These boards are popularly used for suspended ceilings and used in this work as they have adequate ...
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... made from gypsum (6 mm thickness) and laminated by thin carton sheets (1 mm) from both sides for strengthening. These boards are popularly used for suspended ceilings and used in this work as they have adequate strength to carry the heavy-weight concrete layer along with high content of gypsum mortar that used for cladding in the Iraqi buildings (Fig. ...
Context 4
... increased cooling loads [20]. The standard Isogam layer (0.4 mm thickness and 10 m long) composed of bitumen-rubber mastic and laminated from both sides with thin plastic layers. One of the layers coated with light-silver colour to reflect the fallen solar radiation and the other is melted by fire to stuck on the concrete roof during installation (Fig. 2a). The reflective layer is removable and highly influenced by changeable weather conditions, limiting its reflectivity after a short term of installation. Therefore, Isogam with removed reflective layer is used in the present work in order to test the PCM thermal behaviour at high exterior surface temperatures, which is the core of the ...
Context 5
... according to mixing ratio 1:2:3 of the raw materials (cement: sand: gravel) that is popular used for residential building roofs in Iraq, providing compressive strength 25-30 Mpa [21,22]. The raw materials were mixed with water to fabricate the concrete mixture, which then poured into moulds and left dried naturally to form the concrete layers (Fig. 2b). (iii) Gypsum board (cladding layer): Pre-fabricated gypsum boards (8 mm thickness) were used in this work. Boards are made from gypsum (6 mm thickness) and laminated by thin carton sheets (1 mm) from both sides for strengthening. These boards are popularly used for suspended ceilings and used in this work as they have adequate ...
Context 6
... made from gypsum (6 mm thickness) and laminated by thin carton sheets (1 mm) from both sides for strengthening. These boards are popularly used for suspended ceilings and used in this work as they have adequate strength to carry the heavy-weight concrete layer along with high content of gypsum mortar that used for cladding in the Iraqi buildings (Fig. ...

Citations

... Adaptation of PCM in building envelope can be accelerated by developing ways to incorporate it with existing building materials. Investigation in this area shows that incorporating PCMs in building aggregates resulted in reduced performance of aggregate dopped with PCMs was similar to that of raw PCMs [16]. Various other methods of incorporating PCMs in the envelope of structures such as in wall panels, mortar etc have been studied extensively [17][18][19][20][21]. ...
Article
Due to the raise in global warming and green house effects, the concept of energy efficiency is increasingly investigated in recent times. Among the different methods of achieving energy efficiency, passive cooling techniques can be suitable option for achieving intensive interior temperature maintenance. In this work, a novel form stable phase change material (FSPCM) was developed using expanded perlite. The developed FSPCM was implemented for a real time building model to understand the efficiency in reducing the internal temperature. In total, four scaled building models were developed with different roof setups such as (i) conventional RC roof installed with clay tiles, (ii) conventional RC roof installed with cool-roof tiles, (iii) Roof installed with macro-encapsulated PCM tile, (iv) roof installed with FSPCM tile. All the scaled prototypes were installed with temperature sensors for monitoring the reduction in internal temperature and to compare the efficiency of the different models. All the temperature data measured were recorded using an Arduino based data acquisition (DAQ) system. In addition to the experimental studies, a detailed 2-D finite element analysis (FEA) was performed using the commercial ANSYS software with the aim of performing a detailed parametric study.
... Besides, most experimental studies did not consider all influential aspects of PCM incorporation, such as the optimal PCM position, optimal thickness and the proper encapsulation method, mostly conducted numerically [41,42]. Therefore, this research aims to consider all these aspects that we investigated previously (i.e., the optimal PCM position [43], quantity [44] and the best encapsulation method [45,46]) to study the PCM thermal performance incorporated typical residential construction materials. A detailed energetic and thermal comfort assessment was conducted under a severe hot climate of Al Amarah city, southern Iraq, where the temperature often reaches 50 • C during summer days. ...
... The PCM panel used in the roof combination of the PCM room was made of galvanised steel sheet (0.5 mm thickness) with dimensions of 100 × 100 × 1.5 cm. According to our previous investigation, this panel thickness is the bestthermally performed under the exact location [44]. Although the panel could carry more than 10 kg of PCM, only 7 kg was poured inside the panel to ensure that no leakage occurs during the melting phase that may result from PCM volume change or possible panel inclination during installation. ...
Article
Full-text available
Phase change materials (PCMs) can beneficially work as a successful thermal energy storage medium in different applications. PCMs have shown a remarkable enhancement in building energy-saving and thermal comfort in hot locations. In this paper, the thermal behaviour of a PCM-enhanced thermally-poor building envelope is studied experimentally. To this aim, two identical rooms, one loaded with PCM (PCM room) and the other without (reference room), are built and tested under a severe hot climate of Al Amarah city, Iraq. Previously examined parameters, such as the optimal position and thickness of the PCM layer in the roof and the best-thermally performed PCM capsules integrated concrete bricks, are considered to build the PCM room. Several energetic and thermal comfort indicators such as maximum temperature reduction (MTR), average temperature fluctuation reduction (ATFR), decrement factor (DF), time lag (TL), operative temperature difference (OTD), discomfort hours reduction (DHR) and maximum heat gain reduction (MHGR) are determined and discussed to show the potential of PCM. The experimental results revealed that the incorporated PCM could remarkably improve the thermal performance of building envelope exposed to high outdoor temperatures. Amongst envelope elements and compared with the reference room, the roof and east wall of the PCM room recorded the best thermal behaviour, where the MTR difference, ATFR, DF, and TL difference reached 3.75 ◦C, 6.5 ◦C, 25.6%, 70 min for the roof, and 2.75 ◦C, 2.4 ◦C, 12.8% and 40 min for the east wall, respectively. Moreover, the PCM room shows a thermal comfort enhancement by 11.2% and 34.8%, considering the DHR and MHGR, respectively, compared with the reference one. The study highlighted that suitable ventilation means are necessary to improve the building performance and reach acceptable thermal comfort when the PCM is incorporated passively.
... Due to their high energy storage density and melting-solidification process, PCM can store large amounts of latent heat within small temperature ranges [13]. Therefore, building envelopes integrated with PCM usually have lower temperature peaks and fluctuations [86] and provide higher time delays to reach peak temperatures, which helps regulate the indoor thermal environment [9] and improve the building's energy efficiency and thermal comfort [14][15][16][17]. For example, Mechouet et al. ...
Article
Full-text available
Phase change materials (PCM) are widely known for their high thermal storage capabilities. They are generally utilized to increase the thermal mass of buildings’ lightweight materials, which improves their thermal performance and reduces the need for air-conditioning systems. PCM layers are commonly applied to the buildings’ interior parts, close to the indoor environment, which helps regulate the indoor temperature. However, few studies reported that PCM application on the exterior of the envelopes increases their thermal insulation, which can reduce the outdoor heat gain. Therefore, this study aims to develop PCM-based composites for the exterior finishes of building walls. To this end, microencapsulated PCM was integrated into the cement render and foamed concrete with different fractions. The developed composites were tested, evaluated, and compared to the composites without PCM integration. The results showed that PCM integration into foamed concrete reduced the density and thermal conductivity to 896 kg/m³ and 0.18 W/mK, respectively, i.e., lower by 50% and 86% compared to the conventional cement render. Besides, PCM integration added thermal energy storage of 38 J/g to the composite, which can improve its thermal mass. Although the compressive strength decreased by 53% with PCM integration into the cement render, it increased by 28-49.7% with PCM integration into foamed concrete due to PCM capsules substituting some of the air gaps. The findings of this study demonstrate a high potential of using PCM-based foamed concrete to produce lightweight cladding panels for building exteriors with improved thermal insulation and thermal mass to reduce external heat gain.
... Several influential parameters need to be studied to use PCMs as efficient as possible for a longer time and minimal operational cost. These are mainly the optimal phase change temperature, the optimal position within the building element, and the optimal quantity to be involved [56][57][58]. Arıcı et al. [59] found that PCM temperature varied between 6 °C to 34 °C and a PCM layer thickness varied between 1-20 mm can improve the building thermal performance and time lag by 10.3 h in three different Turkish cities. Zhang et al. [60] indicated that PCMs of melting temperature varied between 22 °C-28 °C, placed to the interior position with 5mm thickness could reduce the indoor building surface temperature and the heat transfer by 6.6 °C and 52.9% under China weather conditions. All in all, these parameters need to be studied in parallel to obtain the best thermal performance of PCMs [61]. ...
Article
Full-text available
Cooling and airconditioning systems are responsible for the highest energy consumption in buildings located in hot areas. This high share does not only increase the building energy demand cost but also increases the environmental impact, the topmost awareness of the modern era. The development of traditional systems and reliance on renewable technologies have increased drastically in the last century but still lacks economic concerns. Passive cooling strategies have been introduced as a successful option to mitigate the energy demand and improve energy conservation in buildings. This paper shed light on some passive strategies that could be applied to minimise building cooling loads to encourage the movement towards healthier and more energy-efficient buildings. For this purpose, seven popular passive technologies have been discussed shortly: multi-panned windows, shading devices, insulations, green roofing, phase change materials, reflective coatings, and natural ventilation using the windcatcher technique. The analysis of each strategy has shown that the building energy could be improved remarkably. Furthermore, adopting more passive strategies can significantly enhance the building thermal comfort even under severe weather conditions.
... This is because Tm is associated with the range of temperatures during the day under each location. The Tm of PCMs applied for hot location building applications can reach the height of 44 • C [52] and 52 • C [53]. ...
Article
Full-text available
Phase change materials (PCMs) are successful thermal energy storage mediums in many thermal systems, including buildings. Identifying the best PCM candidate is a critical incorporation parameter that influences building thermal performance. This paper discusses the selection of potential PCM candidates that could be applied for building heating applications in cold locations. A qualitative decision matrix (QDM) is applied for several commercial PCMs after an extensive analysis of relevant literature studies. The melting temperature, heat of fusion, thermal conductivity, compatibility, flammability and cost of each PCM are considered in the QDM to find the most suitable candidates with the best effective properties and features. PCM properties/features are assigned with scores and weights in the QDM based on their importance for the application. Three scenarios are investigated in this work, including and excluding the PCM cost with varying and equal weights. Results showed that RT28HC had the highest score in all scenarios, followed by SavE®HS29 in the first scenario (when the cost is included) and PureTemp 32 in the second scenario without considering the cost. The methodology and results presented in this work are believed to be as efficient as logical for future studies compared with the traditional methods that rely on investigating the PCM thermo-physical properties.
... Numerous technical solutions have been introduced and investigated to minimise such a high percentage of thermal load, applying different passive and active techniques [3][4][5][6]. Amongst recent ones, the incorporation of phase change materials (PCMs) with building envelope elements provided a remarkable enhancement in building efficiency considering energy-saving and thermal comfort [7][8][9]. PCMs can work as thermal energy storage in the building envelope by controlling the heat energy during phase transition and work as heat barrier (insulator) or supplier. ...
Article
Full-text available
In this paper, the thermal performance of phase change material (PCM) incorporated concrete bricks is studied experimentally. Four concrete bricks (three with macroencapsulated PCM and one without PCM represented the reference) are fabricated, and their thermal performance is tested under hot climate conditions. The study considered the effect of PCM encapsulation heat transfer area on brick's thermal performance at the same PCM quantity. PCM bricks included three different PCM capsule arrangements in which the first brick involved one bulky capsule (Brick-B, 4*4*10 cm³), the second brick had two capsules (Brick-C, 4*4*5 cm³), and the third brick involved five PCM capsules (Brick-D, 4*4*2 cm³). The peak temperature reduction (PTR), the conductive heat transfer reduction (HTRc), and the time delay (TD) were presented and calculated, taking into account the inner and outer brick surface temperatures of PCM bricks compared with the reference brick. Results showed that concrete bricks' thermal performance could be remarkably improved using PCM even under maximum outdoor temperatures. Moreover, the best thermal performance is reported for Brick-D, in which the maximum PTR, HTRc, and TD are reached 156.5%, ∼61%, and ∼133%, respectively, compared with the reference brick under maximum outdoor temperatures.
... Al-Yasiri and Szabó [108] conducted an experimental study to determine the optimal thickness of a roof incorporating PCM macro-capsules containing paraffin wax of melting temperature 44 • C under the hot climate of Iraq. Three different thicknesses of 10, 15, and 20 mm were studied based on energy indicators, such as ambient temperature, interior surface temperature, and average exterior surface temperature. ...
Article
Full-text available
Latent heat thermal energy storage systems incorporate phase change materials (PCMs) as storage materials. The high energy density of PCMs, their ability to store at nearly constant temperature, and the diversity of available materials make latent heat storage systems particularly competitive technologies for reducing energy consumption in buildings. This work reviews recent experimental and numerical studies on the integration of PCMs in building envelopes for passive energy storage. The results of the different studies show that the use of PCMs can reduce the peak temperature and smooth the thermal load. The integration of PCMs can be done on the entire building envelope (walls, roofs, windows). Despite many advances, some aspects remain to be studied, notably the long-term stability of buildings incorporating PCMs, the issues of moisture and mass transfer, and the consideration of the actual use of the building. Based on this review, we have identified possible contributions to improve the efficiency of passive systems incorporating PCMs. Thus, fatty acids and their eutectic mixtures, combined with natural insulators, such as vegetable fibers, were chosen to make shape-stabilized PCMs composites. These composites can be integrated in buildings as a passive thermal energy storage material.
... Paraffin wax was used as a PCM in this work as it is locally available at a low price and has good thermal and physical properties that make it suitable for different thermal heat storage applications [22,23]. Paraffin's thermal properties, such as its sharp melting temperature, relatively high density, and heat of fusion, are reasonably good compared with other PCMs investigated in the building applications [24]. ...
Article
Full-text available
This study presents the experimental results of concrete bricks based macroencapsulated phase change material (PCM) in different capsule designs (circular, square and rectangular cross-sections). Eight concrete bricks (including a reference brick without PCM) are fabricated, and their thermal performance is tested under hot summer conditions of Al Amarah city, Iraq. The study considered several indicators such as the interior maximum temperature reduction (MTR), decrement factor (DF) and time lag (TL) to compared among tested bricks in addition to the thermal behaviour during melting and solidification of PCM. Results indicated that all PCM based bricks are performed better than the reference brick in which the maximum interior temperature is shaved and shifted. Moreover, the best thermal performance is reported for bricks of large PCM capsules number. Amongst others, the brick-based square cross-section PCM capsules showed the best thermal contribution where the average MTR of 1.88 • C, average DF of 0.901 and average TL of 42.5 min were obtained compared with the reference brick. The study concluded that PCM capsules' heat transfer area is the main parameter that controls PCM's thermal behaviour as long as all PCM capsules have the same PCM quantity and position. Therefore, excessive encapsulation area might influence the thermal performance of concrete brick and should be specified for the efficient use of PCM storage capacity.
Article
There has been growing interest in applying phase change materials (PCMs) in buildings owing to their energy conservation/latent heat storage properties and potential to improve thermal comfort. Various reviews have extensively discussed the thermophysical properties of PCMs and their energy-saving potential in buildings. However, comprehensive reviews on the indoor thermal/ personal comfort behavior of PCMs under different climates remain limited. Therefore, this study aims to present a comprehensive state-of-the-art review of the impact of PCMs on indoor thermal comfort levels in buildings located in cities within different subclimate zones and their personal cooling effect when integrated with clothing (vest). In addition, greenhouse gas (GHG) mitigation potentials and indoor air pollutant emission properties of PCM-enhanced buildings were also reviewed. Hundreds of published articles of PCMs in PubMed and Scopus databases, including a manual search approach, were utilized. The results from this state-of-the-art study have shown that incorporating PCMs in buildings satisfactorily reduced the indoor air temperature of most buildings located in hot climate (BSh, BWh) zones, but very limited studies have been performed in the cold (Dfc, BSk) environments. In general, there was an improvement in the thermal comfort levels of the PCM-enhanced buildings. However, these were mostly assessed using indices such as predicted mean vote, predicted percentage of dissatisfied, comfort index, and total discomfort change, without any comprehensive survey studies (eg, based on sensation votes) using human subjects. The majority of personal cooling studies of PCM-integrated vests/garments showed good improvement in thermal comfort, especially in terms of skin temperature and thermal sensation. However, very few studies have shown a considerable reduction in the GHG emissions of PCM-enhanced buildings, and the knowledge of the long-term carbon dioxide (CO2) reduction capabilities of PCMs is limited. The profiling of PCMs revealed the presence of volatile organic compounds. However, studies on indoor air pollutant emissions and the potential health effects of PCM-integrated buildings are still lacking. The study is crucial to motivating green building engineers, indoor environmental quality (IEQ) researchers, and epidemiologists to embark on potential future research. Innovative technologies such as machine learning, artificial intelligence, Internet of Things, uncertainty analysis, and optimization can be utilized to predict thermal comfort, IEQ, and GHG emissions in PCM-incorporated buildings.
Article
Phase change material (PCM) applied to roofs can weak external heat entering the room to reduce air-conditioning energy consumption. In this study, three forms of macro-encapsulated PCM roofs with different PCMs (RT27, RT31, RT35HC, PT37) are proposed. The effects of PCM thickness, the encapsulation forms, and different PCMs on the thermal performance of the roof are discussed in Moroccan semi-arid and Mediterranean climates. The results show that as the PCM thickness increases, the peak temperature attenuation of the roof inner surface decreases. In two climates, the pure PCM layer among the three encapsulation forms (i.e. pure PCM layer, PCM in aluminum tubes, PCM in triangular aluminum) is the easiest to appear the phenomenon of insufficient heat storage and release, while the reduction of the peak inner surface temperature and time lag is the most satisfying. For the PCM in the aluminum tube, phase change time is the shortest and the latent heat utilization ratio is the highest, while thermal regulation performance is the least satisfying. The PCM in triangular aluminum can improve the latent heat utilization ratio significantly, and its thermal regulation performance is in the middle. In semi-arid climate, the time lag increases with phase change temperature increasing. The time lag could reach up to 6 h with 37 °C phase transition temperature. In Mediterranean climate, the longest time lag with RT31 is 5 h, while the lowest peak inner surface temperature appears with RT27. The obtained conclusions could provide guidance for the application of PCM roofs in these two climates.