Abstract

The paper on the use of Phase change materials in building construction has been a recent development and a keen interest of the researchers have been demonstrated in this regards. Furthermore, there is ongoing research regarding the various applications of PCM. It may be stated in this context that this research project focuses on the types of PCMs used in the building construction industry. In addition to that, this paper provides a significant insight into the methods or techniques employed for integrating or mixing thee PCM with the concrete or other building material. Moreover, the advantages and the limitations of using PCM as a significant building construction material have been evaluated through this paper. Additionally, Arizona Public Service or APS in the Solar Testing and Research (STAR) center or APS STAR center is taken into consideration for their role in conducting relevant, consequential and noteworthy research on the applications of PCM. Furthermore, the applicability of PCM as an alternative to solar power has been considered through the research conducted by the organisation.

The survey and interviews conducted for performing the quantitative and qualitative analysis of the data, illustrates the knowledge of the researchers and junior research fellows at APS STAR center with regards to the particular subject of discussion. It may be mentioned in this context that the thermal storage capacity of PCMs are exploited through this research and the research at the aforementioned organisation. The methodology chosen for the purpose of execution of this research project has been identified to have a positivism philosophy, and a deductive approach for carrying out these research studies.

1.0 Introduction

1.1 Research background

Substances exhibiting thermodynamic properties as a result of the presence of high heat of fusion or latent heat are termed as Phase Change materials. The outcome of the latent heat presents the opportunity for storing and releasing large amounts of energy. The PCMs are capable of demonstrating such thermodynamic properties during the phase change, generally solid to liquid transition, resulting in the heat storage in accordance with the per unit volume of the substance. The PCMs can be classified as organic, inorganic, hygroscopic or even Solid-Solid PCMs. The implementation of the various kinds of PCMs in building construction is dependent on the advantages and the disadvantages that the materials pose in different environment conditions. The thermophysical properties of the PCMs are taken into consideration as selection criteria for the type of PCM for the materials for building construction (Qiu et al. 2017). It may be stated in this regards that the concept of implementation of PCMs for improving the insulation of building materials had been taken into account after the World War II. This research provides an insight into the classification of the PCMs based on their thermophysical properties, along with the techniques implemented for improving the insulation of building materials. In addition to that, this research investigates the various applications of PCMs, including the involvement in building construction.

1.2 Research problems

Often issues with leakage of insulation are noted due to the implementation of high temperatures. However, the encapsulation of paraffin into small spheres, and thereafter mixing with concrete, aids in the building construction purposes. The techniques used in this regard and their efficiency are studied for the purpose of this research paper. Impregnation, immersion and direct mixing are techniques which are emphasized in this paper. Furthermore, the applications of PCM are studied and an evaluation is made regarding which of the techniques may be suited for the construction industry.

1.3 Research objectives

The objectives and sub-goals of the research are detailed below:

• Discussions of the utilization of PCM in construction
• Assessing the advantages and disadvantages of PCM in construction
• Evaluating the issues that get associated with Phase Change Material

1.4 Research questions

The following questions have been formulated to detail the issue that this paper discusses in a better way:

1. How can you define and understand Phase Change Material?
2. How do you assess Phase Change Material in the manufacturing units of construction?
3. Explain the utilization of Phase Change Management and its advantages when related to the construction industries.
4. Explain the disadvantages of the application of PCM in the industry of construction (Paksoy, 2007, p. 67).
5. Identify and discuss the technologies that can be applied for the better utilization of PCM in the industry of construction.

2.0 Literature Review

2.1 Introduction

The study of phase change materials provides a concept regarding the efficiency of the materials, and it has been evident that the use of PCMs results in more energetically efficient buildings. A literature review of the PCM stated by several scholars has been discussed in this regards. The productivity and advantages offered by a variety of PCMs in the building construction industry have been illustrated in this research. In addition to that, the multiple techniques for enhanced PCM integration into building construction work have been mentioned and studied.

Phase Change Material can be described as a substance that has a heat of fusion, which is high. As it possesses this quality it can be melted or solidified at a specific temperature and then it can store as well as release huge amounts of energy. Phase Change Materials can be called as the units of latent heat storage or LHS too, as the substance while turning from solid to liquid or from liquid to solid releases or absorbs a lot of heat. The storage of latent heat can be done in a few ways and through the following changes in the phase of a material:

• Solid to liquid
• Liquid to solid
• Liquid to gas
• Solid to gas

While all these phases are present, PCM involves only the two initial phases, which are the solid to liquid and the liquid to solid phase. The phase change from liquid to gas has a higher degree of the transformation of heat than the solid to liquid or the liquid to solid transitions, the first phase change involves the utilization of high pressures or large volumes in order to store the materials in the gas phase and have been concluded as being impractical for the purpose of thermal storage. On the other hand the solid to solid phase transition is a very slow process that produces low heat. The solid to liquid transitions of PCM initially behave like the sensible heat storage or SHS where the temperature increases constantly log with the absorption of heat. However, the PCMs reach a certain temperature when they melt and then they can absorb huge amounts of heat without rising radically in the temperature. The PCMs are available at a diverse range of temperature, which starts from -5 degree C to 190 degree C. some PCMs are also available at the comfort range of the human beings, which is between 20-30 degree C and are quite effective as well because they are able to store heat 5 to 14 times more per unit volume than the conventional materials of storage like masonry, rock or water.

2.2 Classification of Phase Change Materials

The classification of PCMs can be classified as depicted in Figure 1.

Figure 1: Classification of PCM

(Source: Mishra, Shukla and Sharma, 2015)

2.2.1 Eutectics

The first category can be cites as eutectics, which are commonly called eutectic mixtures. Eutectic mixtures can be considered as PCMs, which are mixtures of two or more substances having low melting points (de Gracia and Cabeza, 2015). The characteristic feature of this mixture is that the mixture melts at the freezing point of one of the two mixtures, which is the lowest among the two. The temperature at which the mixture freezes is termed as its eutectic point. The binary systems of the eutectics have demonstrated freezing points between 16℃ and 51℃, while the melting point has been noted to be between 18℃ and 51℃ (Mishra, Shukla and Sharma, 2015). The latent heat of fusion of this range of melting and freezing points have been noted to be around 120 and 160 kJ/kg. A mixture of Lauric acid (LA) and Capric acid (CA) is often used as an efficient PCM in building construction (de Gracia and Cabeza, 2015). Figure 2 illustrates the melting points of the binary systems of each of the components of the eutectic mixture, namely, Capric acid and Lauric acid (Qiu et al. 2017).

Figure 2: Melting points of the binary systems of Capric acid and Lauric acid

(Source: Bland et al. 2017)

Using the Schroder’s equation to calculate the transition temperatures of the eutectic mixture of LA and CA have been found to be at 19.6℃. Figure 3 depicts the DSC curve of the binary systems of CA and LA. This had been derived through a DSC analysis of the eutectic mixture, when the proportion of the mixture of LA to CA was 34.88% to 65.12% (Bland et al. 2017).

Figure 3: DSC curve of the eutectic mixture of CA and LA

(Source: Bland et al. 2017)

2.2.2 Organic phase change materials

Organic phase change materials are known to have lower thermal conductivity. The increase in the technology of microencapsulation has enhanced the use of organic PCMs. Furthermore, the use of bio-based PCMs may serve as an alternative to the prevalent petroleum-based PCM. for instance, paraffin (C_nH_2n+2)is one of the most examples of bio-based PCMs which offer numerous advantages (Bland et al. 2017). The chemical inertia of paraffins, along with the extensive range of melting temperatures from 200℃ to 700℃ makes it a suitable PCM in building construction (Bland et al. 2017). The advantages include the ability to freeze without much undercooling, non-reactive and safe. In addition to that, the organic PCMs are chemically stable and offer a high heat of fusion. Moreover, the lipid and carbohydrate based PCMs are generally produced from renewable substances, which does not harm the environment. Additionally, it is to be noted that the compatibility of the organic PCMs with the traditional materials of construction are an interesting feature for the purpose of building construction. Regardless, there are certain disadvantages as well, such as the low thermal conductivity offered by the PCMs in their respective solid states, which may be addressed through the high heat transfer rates for the freezing cycles. Furthermore, organic PCMs are flammable in nature and have a low volumetric latent heat storage capacity (Bland et al. 2017). Examples of organic PCMs include phenol, glycerin, formic acid, methyl palmitate, and Paraffin n-Carbons.

2.2.3 Inorganic phase change materials

Inorganic PCMs are generally salt hydrates in nature with the chemical formula (M_nH₂O). As opposed to the organic PCMs, the inorganic PCMs have a high latent heat of fusion and are non-inflammable, which provides better scopes of application for the same. The other advantages offered by inorganic PCMs include low cost and abundant availability, high thermal conductivity, high rates of volumetric storage capacity of latent heat of fusion and a sharp melting point. However, there are a number of drawbacks identified with respect to inorganic PCMs, such as a high volume change, phase separation and incongruous melting on cycling, which may potentially pose a threat to the latent heat enthalpy (Fokaides, Kylili and Kalogirou, 2015). In addition to that, inorganic PCMs are noted to be corrosive to other substances such as metals, and the requirement of nucleating agents is essential as the PCMs are likely to become inactive after repeated cycles. Furthermore, the solid to liquid transition require supercooling which may become potentially problematic to the PCMs. Sodium sulfate (Na₂SO₄·10H₂O), Sodium hydroxide/ sodium carbonate NaOH / Na2CO3 (7.2%) and more can be considered common examples of inorganic PCMs. Since, inorganic PCMs are subject to undergo phase decomposition, the cross-linking enhances the stability of the compound, which may prove beneficial. For instance, HDPE or high density polyethylene is cross-linked when 98% of the heat of fusion is utilised through transition. However, the temperature range for organic PCMs is quite favourable as they offer a wide range, but the inorganic PCMs are active at a temperature range of 30℃ to 600℃ (Kalnæs and Jelle, 2015).

2.3 PCM Incorporations in Concrete

2.3.1 Impregnation

Incorporation of the PCMs into the building materials proves beneficial as it may aid in the storage of thermal energy. However, it may be mentioned in this regards that the additional of the PCMs into the building material, such as concrete allows the increment of efficiency through providing a higher thermal mass, which aids in the provision of a higher energy efficiency. The process of impregnation is one of the many techniques through which PCMs are incorporated into concrete or other building and construction materials (Fokaides, Kylili and Kalogirou, 2015). Impregnation requires three fundamental steps, namely, the evacuation of water and air from the light-weight aggregates. This is performed with the help of a vacuum pump. Figure 4 illustrates a diagram depicting the process of incorporation of PCMs into concrete. The second step entails the absorption of the porous materials or aggregates into the liquid PCM. Finally, the previously soaked PCM aggregates are mixed with the concrete. The formerly soaked PCM aggregates act as a ‘carrier for the PCM’ (Fokaides, Kylili and Kalogirou, 2015). For instance, taking butyl stearate as a PCM, the aggregates expanded shale aggregate (S), normal clay aggregate (C2) and expanded clay aggregate (C1) had been used for a comparative study of porosity of the materials and as a ‘carrier for the PCM’. It was identified that the porosity of the materials had been found to be 0.081, 0.176 and 0.876 ml/g of the aggregates, S, C2 and C1 respectively. The net outcome of the experiments can be illustrated as the capability of the PCM to occupy about 75% of the porous aggregate (Kalnæs and Jelle, 2015).

Figure 4: Incorporation of PCM into concrete

(Source: Fokaides, Kylili and Kalogirou, 2015)

2.3.2 Immersions

The primary principle acting behind this technique has been identified as the capillary action. As opposed to the impregnation technique, wherein the liquid PCM is incorporated into the concrete, this technique entails the building materials such as concrete or bricks and more, to be dipped within the PCM. The liquid PCM is absorbed by the construction material through capillary action. Figure 5 illustrates the procedure of heat absorption of the PCM and the state transition.

Figure 5: PCM transition

(Source: Fokaides, Kylili and Kalogirou, 2015)

It may be mentioned in this regards that the effectiveness of this particular technique implemented is primarily dependent on the capacity of absorption of the concrete or other building materials used for the building purposes. Furthermore, it is also to be noted in this context that the incorporation or integration of the PCM into the concrete results in the negative impact on the properties of the concrete. However, this may be corrected through the selection of the appropriate and the most suitable technique of PCM integration. Investigation by scientists have demonstrated that the absorption of porous materials or PCM into concrete take a few hours in general. The investigation further highlighted that the liquid PCM required at temperature of approximately 80°C±5 in order to soak through concrete blocks (Kalnæs and Jelle, 2015). Furthermore, it was identified that autoclaved concrete blocks have increased porosity, therefore, it has resulted in an increased rate of absorption of the liquid PCM.

2.3.3 Direct mixings

The process of encapsulation has been previously mentioned in the literature. The physically and chemically stable form of the PCM is directly added into the constituents of the building materials. The common processes identified in this regards are namely, emulsion polymerization, interfacial polymerization, spray drying and more. The use of Zeocarbon or Zeolite is implemented in this regards, in order to avoid the breakage of the capsule during the process of direct mixings. The principle behind this has been identified as the surface reinforcement in order to withstand impact or high impact (Stritih et al. 2018).

2.4 Application of PCMs

2.4.1 Building applications

The role of PCM integrated into concrete is known to have multiple applications in several components of building construction. Major components have been identified as:

• Glass windows filled with PCM: The windows in this aspect have double sheets, filled with air-filled gaps between them. Two holes at the bottom of the window are connected to PCM tank and a pump. Furthermore, the pump is connected to the tank containing the PCM in the liquid state. Temperature sensors are enabled, which enables a pre-set temperature and the pump is activated and the air-filled gaps are replaced with the PCM from the tank (Lee et al. 2015). Hence, the PCM starts freezing as a result of the low outside temperature, thereby maintaining the internal temperature.

Figure 6: PCM embedded in a wall system of a building

(Source: Derradji, Errebai and Amara, 2017)

• Under-Floor Electric Heating System: The thermal floor performance of the building may be evaluated through the implementation of PCM for undertaking the under-floor electric heating systems (Karaipekli, Sarı and Biçer, 2016). The components of the heating system include electric heater, wooden floors, air layer, polystyrene insulation, some wooden supporters and PCM.
• Roof integrated with PCM: A thermal PCM storage unit is installed in the iron roof sheets acting as a solar radiation collection in order to heat up the air. The operations may be performed depending on the requirements. For instance, the PCM is melted by pumping air into the thermal storage facility. However, in the absence of heat, an auxiliary gas heater is implemented for heating.
• PCM assisted ceilings: In this case, a ceiling-mounted fan is used for pumping the air out through the heat pipes, while the other end of the storage pipes is considered as a PCM storage module. The phase transition property of PCM is utilised in this regards, during the day, the PCM absorbs the heat, which cools the warm air generated within the room, while the shutters are opened and the fans are reversed at night, thereby facilitating the heating from the PCM when the cooler air passes over the pipes (Akeiber et al. 2016).

2.4.2 PCM enhanced concrete

Thermo-concrete, which is commonly known as PCM enhanced concrete, implements EPS or Expanded Polystyrene that is embedded in Thermo-concrete panels. This technique implements the use of thermal mass technology. PCM is mixed with the concrete is enhance its durability as well as the properties of heat retention and absorption. Furthermore, a series of experiments performed on PCM in SCC or Self Compacting Concrete have been performed taking 1%, 3% and 5% of PCM in the experiments (Kylili and Fokaides, 2016). It has been established that an increase in 1.7, 3.0 and 3.5 times in the samples, with a consistent increase in the levels of PCM. Additionally, the melting temperatures have been in the range of 23℃ to 26℃, which have been identified to play a vital role in influencing the specific heat capacity of the experimental samples (Souayfane, Fardoun and Biwole, 2016).

2.4.3 Thermal Energy Storage and Cooling Power Potential

It has been found upon conducting several experiments that upon incorporating PCM into the walls of an office space, the indoor ambient temperature had been reduced by about 7℃ in the summer, while the ambient indoor temperatures rose by 4℃ in the winter (Kenisarin and Mahkamov, 2016). Furthermore, it had been established that upon integrating PCM into the walls of the office had resulted in reduced energy consumption as well. It may be stated that it had been demonstrated through a series of experiments that the energy consumption of the office had been found to be 33 kWh without the integration of PCM, while upon integration with PCM, the energy consumption had been reduced to 18 kWh (de Gracia and Cabeza, 2015). Furthermore, as an efficient thermal storage system, PCM has a major role to play in the building construction industry. The PCM embedded in the concrete primarily absorbs the surplus heat during the day, and melts. On the contrary, it solidifies on cooler nights and the the heat absorbed is released into the environment. The principle behind the efficiency can be demonstrated in connection with the heat transfer steam/ water that take place in two phases.

2.5 Recent work in the field of PCMs

Efficient energy performance of building is becoming an increasing concern with the rise in global warming and other negative environmental effects. Recent works in this field have primarily contributed to a better understanding of the management of the energy flow within and out of the buildings. The paper by Fokaides, Kylili and Kalogirou (2015), investigates the incorporation of PCM for the transparent glazing development of a building. The paper draws inspiration from the series of experiments conducted at MIT in 1948 by Dr. Maria Telkes. The experiment at MIT focused on the construction of a house with integrated PCM facilities for heating purposes. The principle of the latent heat of fusion of the PCM was taken into account in this regards. Glauber salts were used; however, the experiment had failed after 3 years, which had given researchers an opportunity to explore the field and the applications of PCM in building construction.

It may be mentioned in this context that the paper by Mishra, Shukla and Sharma (2015), explores the possibility of implementation of PCM as a potential thermal storage in the future. It is stated in the research paper that the use of solid-liquid PCMs are predominantly used in the field of building construction. The prime reason has been identified as the higher heat of transformation required in other phase change transitions such as liquid-gaseous state transitions (Hughes and Zaki, 2016). Furthermore, high pressures and larger volume requirements for other phase transition is also a criterion,, making the overall system impractical and complex.

2.7 Assessment of PCM

The use of the phase Change Materials in the areas of construction and development have been initiated in order to improve the performance of energy and to bring thermal comfort as well. The construction industry is expanding rapidly with the increase in population and that is resulting in the increase of the consumption of energy on a regular basis (da and Eames, 2016). The consumption increase is due to the increased demand for the heating of space or the cooling of areas so that the human beings can enjoy thermal comfort. The Phase Change Materials are utilized largely because they can produce energy in huge amounts by solidifying or by melting at a specific temperature. They play a significant role as the device of storage of thermal energy by utilizing the storage density that is high and the latent heat capacity as well.

2.8 Advantages and Disadvantages of PCM

The following are the advantages and the disadvantages that can be evaluated from the application of PCM in the construction industries.

2.8.1 Advantages of PCM

The application of Phase Change Materials in the industry of construction is farfetched. It adheres to a lot of sections of the industry and provides a lot of help to the people working in the industry as well. It makes work easier and swifter (da and Eames, 2016). It helps to bring down the total cost of the budget as well as it has different units through which it can be utilized. It has organic utilization inorganic uses as well as eutectic variations. They separately look after different issues and solve various problems of the construction industry. They provide the following advantages:

Organic

These are Paraffin (C_nH_2n+2), bio-based or Phase Change Materials that are lipid or carbohydrate derived.

• It has a high latent heat quantity.
• These are materials that are non-corrosive.
• The Phase Change Materials that are organic are thermally as well as chemically stable.
• They need little amount of sub-cooling.
• They materials that are organic are both recyclable as well as organic.
• They provide thermal comfort and are efficient that way (da and Eames, 2016).
• The heat of fusion of these materials is high.
• The vapour pressure used is low.
• It has the ability to melt consistently.
• These are non-reactive materials that are safe.
• The PCMs that are lipid based or have carbohydrate can be produced easily from sources that are renewable. 
• The conventional materials of construction are compatible with it (Sharma et al. 2015).

Inorganic

These are the salt hydrates (M_nH₂O)

• These have high latent heat as well.
• The melting enthalpy of these materials is high.
• The Phase Change Materials that are inorganic have high latency and density as well.
• The thermal conductivity of these materials is high.
• The heat of fusion is high.
• The materials are sensible heat storage units or SHS.
• These are non-flammable too.
• The materials have low change of volume (Sharma et al. 2015).
• The PCMs that are inorganic are affordable.

Eutectic

These are inorganic-inorganic or c-inorganic compounds.

These materials have melting temperature which is sharp.

The volumetric thermal storage density of these materials is high as well.

2.8.2 Disadvantages of PCM

The section above have already mentioned what are the advantages of the PCMs that can be used in the industries of construction for better results and financial reduction as well (Sharma et al. 2015). These materials however, have certain disadvantages too when they are put to practical use. These are discussed in the section below.

Organic

• The main issue or problem with the organic Phase Change Materials is that they are not really affordable as they are made with much care and through a complicated process.
• The enthalpy of melting for these materials is relatively low.
• The density of these items is low as well.
• The thermal conductivity of the organic PCMs is equally low.
• The availability of the organic PCMs is rare. They are not very affordable as they are rarely available in the market (Silva et al. 2015).
• The organic materials are quite flammable depending on the type of container they are placed in.
• They go through a change in volume.

Inorganic

• The materials have super cooling issues.
• The materials of the containers of the inorganic PCMs are corrosive.
• The materials go through a separation in phase.
• They go through segregation in phase as well.
• The materials lack thermal stability in them.
• When the materials go through repeated cycles of change the volume of the Phase Change Materials become unstable (Silva et al. 2015).
•  The phase of melting as well as separation goes through a loss of latent heat enthalpy and is not consistent.

Eutectic

• The thermal performance of these materials gets reduced after repeated cycling just like the inorganic Phase Change Materials.
• Volume change is high as well.
• These are highly corrosive substances.
• Thesuper cooling level is high too.
• There is the formation of sharp crystals when the PCM of salt hydrates starts to solidify (Silva et al. 2015). These sharp objects can cause leaks of the macro-encapsulation and is highly possible to happen.
• The data on the thermo-physical characteristics of these materials are limited.
• There is a lack of practical test of these materials too.

2.9 Technologies applied in PCM

The technologies that are used for the application of PCM in the industries of construction are of different types. These technologies are initiated in the structure of the building or in the water usage systems as well. The technologies are of various kinds and are detailed below:

• Wallboard provides a suitable area for the application of the Phase Change Materials. They have the ability to enable cooling that is off-peak and solar heating that is passive(Silva et al. 2015). These walls where the PCM have been added save almost 5-12% on the cost of heating. The performance after application is measured by the temperature of melting, the effectiveness of the method of incorporation, conditions of climate, solar gains that are direct, and many more of the PCMs.
• Concrete used in PCMs help to save the cost and loses the storage capacity of heat that is high. The concrete usage in PCM has been enhanced in order to increase stability, avoid chances of leakage and improve the thermal performance.
• Ceilings and floors fabrication have been done using the solar heating that is passive and it has been coupled with the PCM night cooling (Kensby et al. 2015). The solar heating that is passive when connected stores the heat until it is required and does not depend on the external solar heating.
• Insulation is a concept on which there has been investigation. It was found that the cellulose that is incorporated in PCM and the insulators of PU-foam reduced the peak-load generated from the walls to about 40%. The insulators can be fitted to the attic insulation and when the summer temperature is at its peak, it can bring down the temperature from 43 degree C to 32 degree C (Su et al. 2015).
• Shutters or window blinds that have PCM incorporated into them reduced almost 10 K in the blind temperature and cause a delay of 3 hours as well. The application of this PCM technology in the building provides a thermal inertia or resistance, which is high and increases the effectiveness of the modules of standard buildings.
• Cooled ceilings are part of the dynamic building application of PCM and the technology of cooled ceilings was able to identify the incorporation of the MPCM slurries and the fluid of heat transfer (Su et al. 2015). This module can help the construction of buildings under different climatic conditions, which can affect the tank size of storage or the pump capabilities.
• Air-conditioning systems has the slurries that have dual functions, to store heat and to transfer them too. The thermal capabilities of these slurries reduced the areas of heat transfer and the reduction continued on the AC units as well (Ramakrishnan et al. 2015). A system called Cool-Phase has been developed in order to heat the office spaces.
• Microencapsulation can be included in the walls made of plastic to avoid any kind of liquid leakage as well.
• Granules embedded with PCM have been developed to avoid the leakage of liquids.

2.10 Summary

As a result of the extensive storage capacity of the PCMs, their widespread applications have been noted in the field of building construction. Relevant literature classifies the PCMs based on the physical, chemical as well as thermo physical properties of the related PCMs. The primary applications of PCM in building components such as windows, wallboards, roofs and ceilings have been identified in this regards. Furthermore, thermal energy storage is a potential aspect explored through the study of the existing literature by scholars and researchers.

2.11 Conceptual framework

3.0 Methodology

3.1 Introduction

The methodology implemented for carrying out a research is one of the most significant and rudimentary aspects of a research paper. The methodology discusses the various research designs which may potentially be implemented. The rationale behind the researcher choosing a particular research approach, philosophy and research design sets the background for the research. A concept of the types of analysis to be used for evaluating the data is discussed as well. Furthermore, the type of sampling and the sample size for the research is also mentioned in the methodology. The methodology also provides an insight into the approximate time frame designed for the research to be completed.

3.2 Research outline

This research is primarily focused on the study of the various types of PCMs in existence, and the ones which are predominantly used in building construction. This research aims at discussing and evaluating the chemical and the thermophysical properties of PCMs implemented in the construction industry. Furthermore, the research explores the efficiency of the methods or techniques identified for integrating PCMs into the building materials such as concrete or bricks. It may be stated in this regards that the development of adequate and suitable strategies is essential for carrying out the research effectively. A proper research approach as well as research philosophy has been found to influence the research outcomes. Therefore, proceeding with an appropriate research design is crucial for the productivity of the research. A descriptive design is followed in this regards in order to maintain the flow of the research. Data collection has been performed from both primary and secondary sources. Moreover, qualitative as well as quantitative data analysis has been performed in the study by the researcher for developing a thorough concept of the subject for research. The research onion provides a significant insight into the concepts involved in conducting a research, as illustrated in Figure 7.

Figure 7: Research onion

(Source: Saunders et al. 2015)

3.3 Research philosophy

Research philosophy fundamentally entails the belief of the researcher to proceed with the research, following a particular procedure of data collection, data analysis and usage of the data. Positivism is the philosophy used in this research. The primary objective or rationale for choosing this particular research approach is that positivism deals in the knowledge based on the relations and properties of natural phenomena. Furthermore, the interpretation of the information or data derived from primary and secondary sources takes place through logic and reasoning. In this regards, the implementation of PCM in building construction provides a scope for the rational analysis and interpretation based on logic. In addition to that, it may be mentioned in this context that positivists approach the challenge or the issue with a scientific quantitative methodology. On the contrary, the interpretivism philosophy has been found to be more suited for qualitative approaches towards research work. Therefore, it may be stated that the researcher finds the positivism philosophy to be more suited for the purpose of the research.

3.4 Research approach

Research approach may refer to the procedure or plan which outlines the methods for data collection for the research and more. The research approach for a research is chiefly based on the nature of the research problem identified in the paper. It provides a rudimentary idea for the assumptions of the detailed methods followed for data analysis, evaluation and interpretation. The chief research approaches commonly used in research include deductive and inductive approaches. The researcher implements the use of a deductive approach in this regards as it is concerned with the development of a hypothesis which is based on existing literature or theories by scholars. Furthermore, a research strategy is developed for testing the hypothesis. Therefore, it may be stated that an overall scientific approach is implemented for the purpose of the research. However, an inductive approach is not used as it is associated with the development of a new theory based on the findings of the data. The deductive approach aims at justifying or analysing the existing literature for establishing the validity of the research regarding the implementation of PCM into building construction.

3.5 Research design

The research design primarily refers to the arrangement of collection or conditions required for a research. For instance, the researcher has previously mentioned that a descriptive design has been implemented for this particular research study. The descriptive designs followed include surveys and naturalistic observation of the case of PCM integration into building construction. Correlational or experimental designs have not been used in this regards, since the researcher aims at studying the existing theories with regards to PCM integration in concrete and other building materials. Hence, it may be stated that the research approach, philosophy as well as the research design has been chosen in accordance to the subject and the research problem identified in this regards.

3.6 Data type and sampling

A mixed methodology has been implemented by the researcher for the purpose of this research. The data collected for this research have been gathered from both primary and secondary sources. The selection of appropriate and adequate data is crucial for a research as it determines the reliability or validity of a research. The primary purpose of the data is to undertake a suitable analysis, along with substantiating the research. Both primary and secondary data have been gathered by the researcher, for conducting a series of quantitative and qualitative analysis for the research. Questionnaires were used as tools for conducting the survey and the interviews for the data collection for the quantitative and the qualitative analyses respectively.

A sample size of 50 for selected for the purpose of conducting the interviews for quantitative data analysis, while 3 Researchers were selected for interviews for qualitative purposes. The sample size was chosen from the research centerArizona Public Service (APS) Solar Testing and Research (STAR) center, which is regarded as one of the largest research organisations in the world. Random sampling was performed, with the objective of deriving the knowledge of the executives with regards to the integration of PCMs into building materials for construction purposes. Furthermore, the sample size was selected to be 50 as a larger sample size reduces the scope of errors due to handling and statistical calculations.

3.7 Data analysis

Relevant information has been gathered from both primary and secondary sources as formerly mentioned by the researcher. Primary data refers to the data collected by the researcher through conducting surveys and interviews. On the other hand, secondary data can be cited as information or data gathered from sources which have previously been in existence (Kylili and Fokaides, 2016). For instance, data from published works of researchers and scholars, peer-reviewed journals and more can be examples of secondary sources of data. Furthermore, the researcher has performed a quantitative analysis on the statistical data gathered from primary sources through the survey. On the contrary, a qualitative analysis has been performed on the data collected through the interviews with the Researchers at Arizona Public Service (APS) Solar Testing and Research (STAR) center with regards to the integration of PCMs in construction materials and their productivity. It may be mentioned that another qualitative analysis had been undertaken by the researcher on the secondary literature available from journals and other scholarly articles. Separate questionnaires have been prepared as tools for gathering the primary data for both quantitative and qualitative analysis purposes. Close-ended questions were included in the questionnaire for the survey, while the questionnaire for the interview comprised open-ended questions.

3.8 Limitations of the research

The consideration of larger sample sizes result in the likelihoodof errors inhandling as well as in the calculation of the data for analysis purposes. In this regards, the researcher chose a sample size of 50, which is neither small nor quite extensive. Therefore, the chances of statistical errors remain. Furthermore, gaining the appointments with the researchers at Arizona Public Service (APS) Solar Testing and Research (STAR) center proved time-consuming and difficult to obtain. Additionally, the survey with the researchers and engineers required convincing regarding the purpose of the survey and the research.

3.9 Ethical considerations

The code of conduct followed at Arizona Public Service (APS) Solar Testing and Research (STAR) center was maintained for the interview and the survey. Furthermore, compliance with legal and ethical obligations has been met with. Informed consent has been obtained from the sample size as well. Furthermore, the researcher had ensured that voluntary participation of the respondents in the survey and the interview. Lastly, the anonymity and the confidentiality of the participants had been maintained as a direct outcome of the code of conduct.

3.10 Timeframe

A Gantt chart is provided as depicted in Figure 8, to develop a concept of the time frame and the activities undertaken on a weekly basis by the research. The overall project was completed in a span of 16 weeks.

Figure 8: Gantt chart

(Source: Author’s creation)

Tasks	Week 1-2	Week 3-4	Week 5-6	Week 7-8	Week 9-10	Week 11-12	Week 13-14	Week 15-16
Selection of the topic and approval proposal
Secondary data collection and literature review
Identifying the research methodology
Collection of primary data
Analysis of data
Findings
Recommendation and conclusion
Final submission and celebration

4.0 Experimental setup

The utilization of the Phase Change Material in the construction industry will be discussed and evaluated in the section below. This is a field set that will be able to assess the concept in regard to the construction industries and I have taken up this topic for discussion as well as evaluation because it is a topic that fits perfectly with the construction industry and benefits it in various ways. As stated by Fleischer(2015, p. 89), the researcher who is conducting the study in order to generate significant data related to this topic and to analyze the data accordingly, is doing it despite of the fact that the respondents of the questions might not be 100% accurate. The researcher will continue to conduct the study even though there is no guarantee against it. Therefore, the person has adopted the method of placing close-ended queries or questions to the respondents because open-ended questions require certain specifications and details that the respondents might not be able to provide correctly. It is easier to answer questions that have a close end and the research based on it will be concluded a lot faster if the information is collected by this method (Cwiok, 2016).

The best possible respondents who can provide detailed answers to any questions regarding the Phase Change Material are the Researchers and the contractors who work in the construction industry and use the Phase Change Material on a regular basis(Ramakrishnan et al. 2015). They know the details of the concept and can give the accurate data, which is why the study was conducted in the internal operational units of the construction industry. The data for the Phase Change Management was collected by interacting with the above mentioned people physically and it took almost 3 weeks to complete the process. For the collection of data the Arizona Public Service or APS in the Solar Testing and Research (STAR) center was selected, which is located in Tempe, Arizona. After the step of collection of the data is done, the research will be carried on further by observing and analysing the collected data. Interviews will be arranged for further data collection by developing a questionnaire, which will be presented to the Researchers and contractors. The proper channeling of all these steps will help the research to reach to a positive conclusion (Dan, 2018, p. 98).

5.0 Data analysis and discussion

5.1 Introduction

Data analysis conducted in this regards have been performed in two stages as previously mentioned. A quantitative analysis has been performed through the survey conducted with the chosen sample size of 50 comprising the employees of Arizona Public Service (APS) Solar Testing and Research (STAR) center. Furthermore, the qualitative analysis was performed on the primary data derived from the interview of the Researchers at Arizona Public Service (APS) Solar Testing and Research (STAR) center, while a secondary qualitative analysis was performed on existing literature on the subject from scholarly articles and published journals.

5.2 Quantitative analysis

The quantitative analysis and the discussion for the survey is provided below:

Q1: The infusion of building materials with PCM aids in cooling in summers and maintaining a warm temperature in winter due to the latent heat of fusion. Would you say that integrating PCM into building materials enhance energy efficiency of the buildings?

Table 1: Response to Q1

(Source: Author’s creation)

Response	Number of respondents	Total number of respondents	Response frequency
1. Agree	17	50	34%
2. Strongly agree	20	50	40%
3. May be	13	50	26%
4. Disagree	6	50	12%
5. Strongly disagree	4	50	8%

Figure 9: Statistical representation of Q1

(Source: Author’s creation)

Energy efficiency is one of the major factors taken into consideration these days while constructing buildings. The heat retention and cooling properties in warm weather makes PCM effective in providing energy efficiency and offers beneficial building properties. 74% of the respondents agreed that the phase transition properties as a result of the heat of fusion of PCM aid in the enhancement of energy efficiency of buildings. 26% of the sample size remained unsure of the choices, while 20% disagreed. Therefore, taking the response into consideration, it may be stated that the properties of PCM aid in the making of energy efficient buildings.

Q2: What would you say is the prime disadvantage associated with the application of PCM in the construction industry?

Table 2: Response to Q2

(Source: Author’s creation)

Response	Number of respondents	Total number of respondents	Response frequency
1. Prolonged payback period	14	50	28%
2. Low thermal conductivity	15	50	30%
3. Phase segregation	13	50	26%
4. Super cooling	5	50	10%
5. Fire safety	3	50	6%

Figure 10: Statistical representation of Q2

(Source: Author’s creation)

When questioned about the potential drawbacks of the integration of PCM in the building construction industry, 30% of the respondents said that low thermal conductivity is to be regarded as one of the major limitations of PCM integration in this regards. Furthermore, 28% of the participants stated a longer payback period to be a drawback. In addition to that, 26% of the sample size said that phase segregation may pose as a drawback as well. 10% of the population mentioned super cooling as another factor contributing to the pitfalls of PCM as a disadvantageous building material. Finally, 6% of the sample size considered the aspect of fire safety as well.

Q3: What is the biggest advantage of using PCM in the construction industry?

Table 3: Response to Q3

(Source: Author’s creation)

Response	Number of respondents	Total number of respondents	Response frequency
1. Non-corrosive	6	50	12%
2. Self-nucleating properties	8	50	16%
3. Thermal storage	23	50	46%
4. Energy loss prevention	10	50	20%
5. Other	3	50	6%

Figure 11: Statistical representation of Q3

(Source: Author’s creation)

The biggest advantage identified by the respondents with regards to PCm incorporation in building construction is the capacity for thermal storage. 46% of the participants voted in favour of thermal storage capacity of PCM. In addition to that, 20% of the population mentioned the prevention in energy loss to be a significant factor, while 16% and 12% of the sample size respectively stated self-nucleating properties and non-corrosive nature as valuable contributions to the advantage of PCMs. however, only 6% of the participants stated that there may be other advantages apart from the aforementioned ones.

Q4: Due to the thermal storage capabilities of PCM, it is used for cooling and heating of buildings. Do you agree that PCM is an efficient and recommendable thermal storage material in the construction industry?

Table 4: Response to Q4

(Source: Author’s creation)

Response	Number of respondents	Total number of respondents	Response frequency
1. Agree	16	50	32%
2. Strongly agree	24	50	48%
3. May be	5	50	10%
4. Disagree	4	50	8%
5. Strongly disagree	1	50	2%

Figure 12: Statistical representation of Q4

(Source: Author’s creation)

80% of the respondents agreed that PCM is a recommendable and efficient thermal storage material in building construction industry. However, 10% of the participants remained neutral or unsure of their choices, while another 10% disagreed with the statement. Hence, it is evident that majority of the population in the industry of building construction would recommend PCM as an effective component in buildings.

Q5: What technology would you recommend for the better integration of PCM in construction industry?

Table 5: Response to Q5

(Source: Author’s creation)

Response	Number of respondents	Total number of respondents	Response frequency
1. Heat exchanger plate in HVAC	11	50	22%
2. PCM capsule incorporation into buildings	24	50	48%
3. Impregnation	10	50	20%
4. PCM integrated panels	13	50	26%
5. Other	2	50	4%

Figure 13: Statistical representation of Q5

(Source: Author’s creation)

The integration of PCM capsule into buildings or direct integration is chosen to be one of the major technologies to be implemented in building construction. 48% of the respondents chose the integration of PCM capsule option, while 26% of the sample size voted for PCM integrated panels, which has become a common activity in building construction. 22% and 20% of the participants stated that the implementation of heat exchangers in a HVAC system, and impregnation to be the next technological development in PCM, respectively. Only 4% of the participants suggested the use of other technological developments.

Q6: Do you think that the CFD analysis is an effective method of reducing the variations in temperature of the room as well as the air temperature?

Table 6: Response to Q6

(Source: Author’s creation)

Response	Number of respondents	Total number of respondents	Response frequency
1. Agree	16	50	32%
2. Strongly agree	18	50	36%
3. May be	10	50	20%
4. Disagree	3	50	6%
5. Strongly disagree	3	50	6%

Figure 14: Statistical representation of Q6

(Source: Author’s creation)

68% of the participants agreed that the CFD analysis is an effective way for reducing the temperature variations in a building. In addition to that, 20% of the population remained unsure of their choices, while 12% of the respondents disagreed with the statement. Hence, the effectiveness of CFD analysis as a method for assessing the temperature reduction in buildings has been validated through the survey.

Q7: The use of autoclaved concrete blocks increases the porosity of the concrete. Does the application of this principle in immersion technique prove beneficial for construction purposes?

Table 7: Response to Q7

(Source: Author’s creation)

Response	Number of respondents	Total number of respondents	Response frequency
1. Agree	13	50	26%
2. Strongly agree	17	50	34%
3. May be	12	50	24%
4. Disagree	5	50	10%
5. Strongly disagree	3	50	6%

Figure 15: Statistical representation of Q7

(Source: Author’s creation)

In addition to soaking the PCM in concrete, it has been noted that another technique, namely autoclaving the concrete blocks aid in the increase in porosity of the concrete blocks. Furthermore, the primary principle identified in regards have been mentioned to be the capillary action which enables the absorption of the liquid PCMs. 60% of the respondents agreed that autoclaving improved the absorption of the concrete blocks. 24% of the participants remained unsure, while 16% disagreed.

Q8: Would you say the incorporation of PCM in building construction is cost effective?

Table 8: Response to Q8

(Source: Author’s creation)

Response	Number of respondents	Total number of respondents	Response frequency
1. Agree	6	50	12%
2. Strongly agree	8	50	16%
3. May be	10	50	20%
4. Disagree	12	50	24%
5. Strongly disagree	14	50	28%

Figure 16: Statistical representation of Q8

(Source: Author’s creation)

Only 28% of the sample size stated that the incorporation of PCM into building construction is cost-effective, while 20% of the population remained neutral regarding the subject. However, a massive 52% of the participants of the sample population disagreed with the statement. Hence, it is evident that PCM integration into building construction is not quite cost-efficient, as outlined in the identified disadvantages of PCM integration.

Q9: Does Arizona Public Service (APS) Solar Testing and Research (STAR) center consider the implementation of PCM in building construction industry to be a part of the renewable energy resource experimentation?

Table 9: Response to Q9

(Source: Author’s creation)

Response	Number of respondents	Total number of respondents	Response frequency
1. Agree	14	50	28%
2. Strongly agree	22	50	44%
3. May be	10	50	20%
4. Disagree	3	50	6%
5. Strongly disagree	1	50	2%

Figure 17: Statistical representation of Q9

(Source: Author’s creation)

72% of the respondents agreed that Arizona Public Service (APS) Solar Testing and Research (STAR) center considers the implementation of PCM in building construction industry to be a part of the renewable energy resource experimentation. 20% of the participants remained neutral in this regards, while 8% disagreed with the statement. Hence, the applications of PCM as an alternative to certain renewable sources have been evident through this survey.

Q10: Would PCM be able to contribute to the existing research of Arizona Public Service (APS) Solar Testing and Research (STAR) center in the search of alternatives to solar power and other renewable sources?

Table 10: Response to Q10

(Source: Author’s creation)

Response	Number of respondents	Total number of respondents	Response frequency
1. Agree	15	50	30%
2. Strongly agree	21	50	42%
3. May be	8	50	16%
4. Disagree	4	50	8%
5. Strongly disagree	2	50	4%

Figure 18: Statistical representation of Q10

(Source: Author’s creation)

72% of the respondents agreed that PCM would be able to contribute to the existing research of Arizona Public Service (APS) Solar Testing and Research (STAR) center in the search of alternatives to solar power and other renewable sources. However, 16% of the participants remained unsure of their choices, while 12% of the population disagreed with the statement. Hence, the research and the series of experiments conducted on PCM at Arizona Public Service (APS) Solar Testing and Research (STAR) center have been found to be of utmost importance.

5.3 Qualitative analysis

The qualitative analysis from the primary source of information has been gathered from interviews with researchers of Arizona Public Service (APS) Solar Testing and Research (STAR) center.

5.3.1 Primary sources

Q1: How do you comprehend PCM?

Table 11: Response to Q1

(Source: Author’s creation)

Researcher 1	Researcher 2	Researcher 3
PCMs are effective thermal storage components in building construction industry	PCMs are primary materials which are capable of solidifying and melting at certain temperatures, with  a sufficient thermal storage capability	PCMs exhibit a high heat of fusion which demonstrate the ability to store heat, therefore resulting in its widespread integration in building construction

From the above interview with the chosen researchers at APS STAR center, it becomes evident that the primary concern of the researchers regarding PCM is related to its distinct properties of phase transition, high heat of fusion and more. Furthermore, the outcome of the high heat of fusion has been noted to be an important component in thermal storage systems implemented in building construction. In addition to that, it may be stated that the characteristic feature of PCM for melting and solidifying at convenient temperatures make it suitable for implementation in building construction industry.

Q2: Could you explain the role of PCM in construction manufacturing?

Table 12: Response to Q2

(Source: Author’s creation)

Researcher 1	Researcher 2	Researcher 3
As a result of a significant climatic change, PCM finds a way into the integration into buildings for maintaining the variance in temperature	PCM is widely used in the manufacture of glass windows with PCM integrated within it. Furthermore, roofs, ceilings, and floors are often integrated with PCM for maintaining temperature variance and thermal storage facilities	Organic, inorganic and Bio-based PCMs are widely implemented depending on the nature or type of advantages expected from the PCM integration into building construction

The use of PCM in the construction industry has been primarily identified with regards to its properties for maintaining the temperature variance between the room temperature as well as the air temperature. PCM is noted to be incorporated into building materials such as glass windows, panels, roofs, ceilings and floors. Furthermore, the use of PCM has been identified in the HVAC systems as well.

Q3: Could you enlist some problems or issue associated with the integration of PCM into buildings?

Table 13: Response to Q3

(Source: Author’s creation)

Researcher 1	Researcher 2	Researcher 3
One of the major drawbacks identified with regards to PCM is the low thermal conductivity	While PCM demonstrates strong attributes for implementation of PCM in building construction, the commercial aspects require the consideration of the cost-effectiveness of the materials as well. However, PCM is noted to be comparatively expensive for implementation.	The stability of the PCM during the cycles of phase segregation or phase separation has been a major challenge identified with regards to the integration of PCM in building construction

The drawbacks or limitations perceived with regards to PCM in the building construction industry can be stated as low thermal conductivity, commercially expensive integration as well as the general instability of the PCMs during cycles of phase segregation or phase separation. 

Q4: What can you say about the capability of PCM as a potential cooling and thermal storage component?

Table 14: Response to Q4

(Source: Author’s creation)

Researcher 1	Researcher 2	Researcher 3
The integration of PCM is widely prevalent in glass windows, as roof integration and under-floor thermal storage component. PCM is used for its thermal retention and cooling characteristics for a component in building construction.	Glass windows are often integrated with PCM and gaps are left filled with air. However, the phase transition properties of PCM enable the cooling and heating as per requirements.	The phase transition properties make PCM one of the most coveted components in building construction. The melting points of the PCMs provide thermal storage and potential cooling properties.

The feature of PCM to undergo cooling and heating and thereby a phase transition aids in the retention of heating and thus providing heating and cooling facilities for the buildings, as a result of the higher thermal mass of the PCM. The thermal mass and the thermal conductivity offered by the PCM are dependent on the type or category of PCM. For instance, inorganic PCM offer higher thermal conductivity as compared to organic PCMs.

Q5: What would you say about the uses of PCM in construction of buildings; how is it beneficial?

Table 15: Response to Q5

(Source: Author’s creation)

Researcher 1	Researcher 2	Researcher 3
The non-corrosive nature of the PCMs has been attributed as one of the major advantages of using PCM in building construction	The self-nucleating properties of PCM serve as an effective property for integration into building construction. This property enables the thermal stability of the substances with respect to the variation in temperature	Energy efficiency in buildings through thermal storage adds to the major scope of PCM integration into building construction industry

The uses of PCM and the benefits noted through the integration of PCM in construction industry can be attributed to the non-corrosive nature, the self-nucleating nature as well. The self-nucleating properties have been known to be associated with the stability of the PCM even with the inconsistent temperature fluctuations. In addition to that, the recent emphasis on being energy efficient is noted to be a significant trend in the building construction industry. Therefore, the incorporation of PCM into buildings may aid in the development of energy efficient buildings, which may contribute to a healthy and sustainable environment as well.

4.3.2 Secondary sources

Memon et al. (2015), studied the characteristics of a light-weight aggregate of paraffin, which is macro-encapsulated. The macro-encapsulation had been performed through the vacuum impregnation of the LWA or light weight aggregates with the paraffin. The storage capacity for the latent heat of the prepared aggregate had been found to be approximately 102.5 J/g, with a sustenance of 1000 melting and freezing cycles (de Gracia, 2019). In addition to that, the compressive strength of the aggregate prepared had been established to be around 33.29 to 53.11 MPa, which makes it appropriate or suitable for implementation in construction purposes.

Furthermore, research performed by Stritih et al. (2018), discusses the implementation of PCM in building materials for the overall output of a net zero building. The articles mention the implementation of PCM into a composite wall in order to address the temporal gap between energy supply and energy demand. Hasan et al. (2016), in their scholarly article discuss the heat gain prevention of buildings in hot climates, through the integration of PCMs into the building materials. It is to be mentioned in this context that 44% heat reduction had been noted in this experiment upon the integration of PCM into the chamber.

The paper by Konuklu et al. (2015), evaluate the use of microencapsulation techniques for the integration of PCMs into variety of building materials. The size of the microcapsules has been estimated to be approximately within the range of 0.05 μm and 5000 μm (Mohseni, Tang and Wang, 2017). As stated by Su et al. (2015), Phase Change Materials are utilized in order to reduce the overall energy that the buildings require only by shifting a part of the loads of the cooling and heating to the hours that are off-peak when the demand for energy is lesser than the peaked hours under one grid (Su et al. 2015). The practices of different types of construction changes with the development of new and better equipment that is innovative. The difference in the temperature in the interior and the exterior part of a place in the winter season or the summer season is done by the consumption of high levels of energy. According to Kensby et al. (2015), the PCMs are thin layered presentations of the walls of large masses, which can be utilized in order to produce thermal comfort in the interior parts of a building (Kensby et al. 2015). The PCMs have the ability to continue the cycle of change without losing their characteristic features and prevents the loss of their mass through the process of evaporation as well.

In the article by Ramakrishnan et al. (2015), it has been stated that the PCMs liquefies and then stores the heat produced and it equally solidifies to release the heat stored (Ramakrishnan et al. 2015). There are a number of applications of PCM in the industry of construction like incorporating it in the structure of the building, tempering with the heating or cooling systems of water, electricity usage in the off-peak time, AC absorption, cool TES, cooling is stored in the night time to be used at the day time, and many more. Therefore, it had been identified that the use of PCM in the construction industry is varied and quite significant as well (Ramakrishnan et al. 2015).

5.4 Summary

The data analysis performed on the quantitative and qualitative data provided an insight into the prevalence and utility of the PCMs in building construction. The effective organic and inorganic PCMs have been identified through the interviews, while the secondary data provides insight into the research by scholars and the significant findings. Relevance with the literature has been observed with regards to the construction of energy efficient buildings through PCM integration into the buildings as well as the increase in thermal conduction and storage through PCM integration as well. Furthermore, the quantitative data provided knowledge of the existing procedures and the techniques deemed to be the most effective by the construction engineers.

6.0 Conclusion and recommendations

6.1 Conclusion

The research project provides an insight into the study of PCMs and their integration into building construction materials. The primary categories of PCMs have been identified as eutectic mixtures, organic and inorganic PCMs. Furthermore, an evaluation of the techniques for the integration of the PCMs into the building materials such as mortar or concrete have been assessed to be performed through the techniques of immersions, impregnation or encapsulation and direct mixing. The use of Zeolite or Zeocarbon has been noted in case of direct mixing technique as it prevents the breakage of the capsule containing the PCM, through resisting the impact. In addition to that, the encapsulations have been established to be performed through a number of techniques such as in situ polymerization, by interfacial polymerization, spray drying and emulsion polymerization.

The various applications of PCM in building construction have been explored in this research project as well. For instance, the development of PCM integrated concrete have been found to effective in heat retention and cooling performance in buildings. Additionally, the it has been found that the increase in porosity of the bricks or concrete blocks can be brought about by soaking in liquid PCMs. Furthermore, autoclaved bricks have been known to have better porosity and air trapping characteristics, which in turn contributes to the heat retention properties of the buildings. However, through further research into the subject, it has been identified that the increase in porosity may result in the slight decrease in mechanical properties, such as compressive strength of a building.

6.2 Recommendations

This research work may be facilitating future works in this particular field. For instance, current works include the development of energy efficient building through the implementation of PCM into various building components used in the construction. Research in the improvement of the weakened compressive strength of buildings upon the integration of PCM can be performed as a potential future study. Furthermore, a detailed study on molecular encapsulation could be undertaken by researchers as alternatives for PCM integration techniques into building materials.

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