PCM-Enhanced Building Components - An Application of Phase Change Materials in Building Envelopes and Internal Structures

Book · January 2015with 308 Reads
DOI: 10.1007/978-3-319-14286-9
Publisher: 978-3-319-14285-2
Publisher: Springer
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Abstract
Presenting an overview of the use of Phase Change Materials (PCMs) within buildings, this book discusses the performance of PCM-enhanced building envelopes. It reviews the most common PCMs suitable for building applications, and discusses PCM encapsulation and packaging methods. In addition to this, it examines a range of PCM-enhanced building products in the process of development as well as examples of whole-building-scale field demonstrations. Further chapters discuss experimental and theoretical analyses to determine dynamic thermal characteristics of building enclosure components containing PCMs, numerical tools which can be used in performance analysis of PCM-enhanced building envelopes, and present different laboratory and field testing methods. Finally, a wide range of PCM building products are presented which are commercially available worldwide. This book is intended for students and researchers of mechanical, architectural and civil engineering and postgraduate students of energy analysis, dynamic design of building structures, and dynamic testing procedures. It also provides a useful resource for professionals involved in architectural and mechanical-civil engineering design, thermal testing and PCM manufacturing.
Chapters (6)
The use of Phase Change Materials (PCMs) as thermal storage systems in buildings has been already of interest throughout almost seven decades. Current improvements in building envelope technologies suggest that residences will soon be routinely constructed with low heating and cooling loads. Most often, latent heat storage materials are used to stabilize interior building temperatures. PCM-enhanced building envelopes offer higher per unit heat storage capacity than conventional building materials and provide lightweight structures the benefit of increased thermal mass. This chapter presents a short history of building envelope applications and whole buildings utilizing PCM.
Modern developments in areas of building technologies and new construction methods have led to reduced build time and cost for residential and commercial buildings. However, they have also resulted in lightweight construction materials with very little thermal mass. Fortunately, PCM-enhanced building components exhibit higher per unit heat storage capacity than more traditional building materials and they can bring additional thermal mass to lightweight building structures. In this chapter, an overview has been made of the thermal energy storage materials with solid–liquid phase change. The following four major aspects have been the focus of this overview: the type of materials, heat transfer characteristics followed by methods of thermal conductivity enhancements, and durability. In addition, PCM encapsulation and packaging methods are discussed here.
A great variety of organic and inorganic phase change materials (PCMs) with stable thermo-physical properties are available and have been used worldwide in heat storage applications. In buildings, both sensible and latent energy accumulation can occur in the external envelope as well as in the internal building fabric. It is well known that one of the effective ways for energy performance improvements and cost reduction of PCM applications in buildings is PCM optimization. This process is usually associated with a proper selection of PCM thermal characteristics, PCM quantity, and its location within the building structure. As expected, this requires an excellent understanding of thermal performance characteristics. Hence, the key interest is focused today on relatively inexpensive and easy-to-use testing methods for determination of thermal characteristics of PCM-based products or systems. This chapter is mainly focused on laboratory-scale thermal-testing methods for PCMs, PCM-enhanced building products, and building envelope systems containing PCMs.
The use of building components utilizing phase change materials (PCMs) has been of interest since the late 1940-s. Full-scale field testing of building envelope components containing PCMs is often a critical last step before market implementation of new products utilizing latent heat. This chapter will focus on two basic forms of these experiments: test hut testing and whole-building experiments. Due to a large number of commercial demonstration projects with use of PCMs, currently taking place around the world, only a limited selection of experiments and demonstration projects from different geographic regions are discussed in this publication.
Energy storage in building envelopes can be accomplished by means of sensible and latent heat accumulation. A large number of numerical tools enabling thermal and energy performance analysis of building envelopes containing PCM have been already developed. They now successfully support numerical optimization of thermal characteristics for building technologies utilizing latent heat storage. At the same time, reliable whole building energy models can numerically facilitate an optimized design of the PCM enhanced building components without the need for time-consuming and expensive whole-building field experiments. This chapter offers a review of the best-known numerical methods useful for the performance analysis of PCM-enhanced building envelopes. It also presents a selection of the most popular computer programs useful for system-scale thermal analysis and several best-known whole building energy simulation tools.
For a variety of climatic conditions, PCM-enhanced building envelope products are widely considered as prospective building technologies which can help in the near future to achieve peak-hour load and HVAC energy consumption reductions. Notable energy savings can be accomplished in residential and commercial buildings, by means of a variety of applications utilizing external envelopes, as well as internal building fabric technologies having capability of sensible and latent heat accumulation. This chapter is mainly focused on most popular building construction products containing PCM. Associated patents are discussed as well.
  • Article
    The conventional indoor climate comfort systems have a major share of energy consumption in residential sectors. Passive design is an approach that can reduce building energy demand by minimizing mechanical systems power consumption. Solar chimneys as natural draught components that utilize solar energy to build up stack pressure are an innovative passive design. Solar chimney contributes to an increase in efficiency for residential space heating and cooling in addition to a considerable reduction of greenhouse gas emissions. This article presents an overview of recent progresses in solar chimney research. The construction industry has a tendency in utilization of integrated solar chimney configurations to improve the level of thermal comfort. In this paper, common integrated configurations based on solar chimneys were summarized. Besides, the challenging aspects and recommendations of each system were mentioned. Combined energy systems based on solar chimney have been regarded as efficient strategies toward green building architecture. Each system has its own pros and cons and there is not a general guideline that can arrange these systems in descending order according to their performance. It is necessary to carry out more experiments to solve forthcoming problems in their commercial applications. Further studies are suggested in developing optimization strategies and control systems. A desirable control system responds to inhabitants needs unobtrusively and allows them to change a condition if it is perceived thermally uncomfortable, with prompt feedback.
  • Thesis
    Full-text available
    The aim of this thesis was to create a simplified method for design of phase change material (PCM) ceilings in office buildings. A parametric study was done for two 2-person offices with PCM ceilings in a building, with nocturnal discharging by ventilation. The purpose was to investigate the effect of different PCM types and load cases on energy use for heating, cooling and ventilation. The parametric study was performed using the simulation software TRNSYS. A total of 2240 simulations with PCM were computed for the climate of Madrid, Dori, Copenhagen, Buenos Aires and Santa Maria. The window size, internal heat gains, PCM type, PCM board thickness, PCM surface area and PCM thermal conductivity were varied. The PCM cases were compared to 20 reference cases to calculate energy savings. The simulation models were validated against a benchmark test and several experiments performed in a climate chamber, which was comparable to the office. The study revealed that PCM ceilings have a potential for energy savings of up to 25.7%, but also that there is a risk of increasing energy use, if the chosen PCM does not suit the climate or load case. Even though the energy savings potential was high, the high cost of PCM products resulted in payback times of more than 20 years, for the majority of the climates. The thesis concludes with a short recommendation on how to choose PCM type and key properties, and a statistical
  • Article
    This work presents a numerical study of the combined effects of the hysteresis temperature difference, peak melting temperature, and thickness of a building envelope PCM-wall on its thermal performance in air-conditioning and non-air-conditioning conditions. The study was carried out considering complete melting-freezing daily cycles of the PCM in a climate exhibiting both hot and cold thermal discomfort. A time-dependent one-dimensional heat conduction code, which uses the effective specific heat method to simulate the heat transfer through the PCM was developed. Insights into the effects of the hysteresis phenomenon were obtained; it was found that hysteresis improves the thermal performance of PCM-walls. The higher the hysteresis temperature difference the better the thermal performance, but there is a limit in the improvement of the thermal performance, which is achieved when the entire phase change process takes place at temperatures outside of the thermal comfort zone. Maximum improvements from 4% to 29% for air-conditioning and from 4% to 30% for non-air-conditioning, for a BioPCM wall with thicknesses from 6 mm to 18 mm, were found. Suggested criteria to achieve the maximum possible thermal performance of PCM-walls given a thickness and use condition were obtained. This work proposes the basis of a methodology to optimize simultaneously any pair of variables of a PCM-wall for different use conditions (AC, nAC, or a combined use of AC and nAC).
  • Article
    Full-text available
    Phase change materials (PCMs) offer great potential as a latent heat energy storage technique to provide energy efficient systems in new and existing residential buildings. Due to their unique characteristic of high storage densities and latent heat properties, PCMs provide opportunities for greater energy storage in many applications for residential buildings. These applications include, but are not limited to, solar water heating, space heating/cooling, and waste heat recovery. This study reviews PCM systems in residential building applications, with a focus on their major disadvantages and concludes with proposals for future development. Several disadvantages of PCM use in the given application have been identified and include; super cooling, low thermal conductivity, phase segregation, fire safety, and cost. The issues caused by super cooling and phase segregation lead to thermal cycling degradation, limiting the useful lifecycle of the material. These issues could limit their potential in building applications, which require systems of a long lifespan. Low thermal conductivities can slow down the rate at which heat is distributed or absorbed from the building, which affect the occupants comfort and as well as the efficiency of the system. Ideas based on the current research on ways to limit these disadvantages are included in the study. This study also identifies that further research is required on novel maintenance ways for the PCM systems after they have been installed.
  • Conference Paper
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    This study examined the performance of Phase Change Material (PCM) in active ceiling panels under extreme climate conditions. The purpose was to reduce the annual energy use and still maintain an indoor climate corresponding to Category II in the European Standard, EN15251. Dynamic yearly simulations were run with a building simulation software for eight climates. The chosen climates were Dubai-UAE, and Tromsø-Norway. Two models of a two-person office were made for each climate; one model with active ceiling with PCM and an all-air ventilation model without PCM to compare the models and investigate the effects of using PCM in active ceilings. The results results show that the PCM models lowered the peak room temperature during the cooling season. None of the PCM models had temperatures outside the desired ranges, and in general provided a more comfortable thermal indoor climate than the all-air system. The PPD level was lower for the PCM models in all of the tested climates, except for the hot climates Dubai and Salvador. The largest differences in energy use were found in the cold climates, namely Moscow, Nuuk and Tromsø. The PCM model of Nuuk used 42% less energy annually than the all-air system, while the PCM models of Tromsø and Moscow had 39% and 30% lower annual energy use, respectively. The PCM models of Istanbul and Dubai showed an energy use 24% and 13% lower compared to the all-air models. The subtropical climates Tokyo and Salvador had an 7% and 2% lower energy use, respectively. Lima was the only climate where the PCM model had a negative effect on the energy use with-20%. The implementation of PCM showed to have the largest benefit in terms of energy use under cold climate conditions; however, all climates, except for Lima, showed that active ceilings with PCM could be implemented with positive effects by lowering the peak room temperatures and the energy use in buildings.
  • Conference Paper
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    The aim of this study was to examine the performance of phase change material (PCM) in active ceilings for an office room under different Danish building regulations for both heating and cooling purposes. A model of a two-person office room was simulated with the only heating and cooling source being radiant ceiling panels containing PCM. The target was to reduce energy use for the simulation models and still meet the recommended criteria of Category II for the European Standard EN 15251:2007namely, 23°C – 26°C (73.4°F – 78.8°F) during summer and between 20°C – 24°C (68.0°F – 73.4°F) during winter. The office model was simulated for a whole year and analyzed for three Danish building regulations BR10 (2010), BR15 (2015) and BR20 (2020). The results show that the indoor environment was within the desired Category II, according to EN 15251 for the whole occupancy period. The predicted percentage of dissatisfied (PPD) was below the desired 10% for Class II of EN15251during 95% of the occupied hours in a year for BR10, 94% for BR15 and 100% for BR20. The use of PCM model decreased energy use by 45% for BR10, 35% for BR15, while it increased by 17% for BR20. The results indicate that active ceilings with integrated PCM could help maintain a satisfactory thermal indoor environment while reducing the energy use. This demonstrated a great potential for PCM to be used to achieve strict energy frame requirements for future low energy buildings.
  • Article
    Full-text available
    The article deals with the use of modern materials and technologies that can improve the thermal comfort in buildings. The article describes the design and usage of a special accumulation device, which is composed of thermal panels based on phase change materials (PCMs). The thermal panels have an integrated tube heat exchanger and heating foils. The technology can be used as a passive or active system for heating and cooling. It is designed as a "green technology", so it is able to use renewable energy sources, e.g., photovoltaic (PV) panels, solar thermal collectors and heat pumps. Moreover, an interesting possibility is the ability to use thermoelectric coolers. In the research, measurements of the different operating modes were made, and the results are presented in the text. The measurement approves that the technology improves the thermal capacity of the building, and it is possible to use it for active heating and cooling.
  • Article
    The improvement of the use of renewable energy sources, such as solar thermal energy, and the reduction of energy demand during the several stages of buildings' life cycle is crucial towards a more sustainable built environment. This paper presents an overview of the main features of lightweight steel-framed (LSF) construction with cold-formed elements from the point of view of life cycle energy consumption. The main LSF systems are described and some strategies for reducing thermal bridges and for improving the thermal resistance of LSF envelope elements are presented. Several passive strategies for increasing the thermal storage capacity of LSF solutions are discussed and particular attention is devoted to the incorporation of phase change materials (PCMs). These materials can be used to improve indoor thermal comfort, to reduce the energy demand for air-conditioning and to take advantage of solar thermal energy. The importance of reliable dynamic and holistic simulation methodologies to assess the energy demand for heating and cooling during the operational phase of LSF buildings is also discussed. Finally, the life cycle assessment (LCA) and the environmental performance of LSF construction are reviewed to discuss the main contribution of this kind of construction towards more sustainable buildings.
  • Article
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    This paper presents a model of a wall with variable properties dedicated to modelling phase change materials (PCMs) in building envelopes. The model is implemented in the TRNSYS simulation tool and referred to as Type 3258. The 1-D conduction heat transfer equation is solved using an explicit finite-difference method coupled with an enthalpy method to consider the variable PCM thermal capacity. This model includes temperature-dependent thermal conductivity and PCM-specific effects like hysteresis and supercooling. The stability conditions are discussed and the algorithm implemented in TRNSYS is described. A numerical validation performed on wall test cases proposed by the International Energy Agency is presented, showing that the developed model is in agreement with reference models. The paper also discusses the impact of temporal and spatial discretization on the model performance. Modelling problems encountered when using an effective heat capacity method (compared to an enthalpy method) and when representing supercooling are also discussed. Accessible on: http://www.tandfonline.com/eprint/QVX6HX3AIg4WGJb3xt5j/full
  • Article
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    Recent studies concerning phase change material (PCM) characterization show that important errors occur if differential scanning calorimetry (DSC) experiments are misinterpreted. Therefore, it is important to know the influence of such misinterpretation on system modeling. The present work deals with phase change materials integrated in building structure to reduce overheating. The objective is to evaluate the discrepancies consequences (temperatures, heat fluxes), due to the use of the misinterpreted DSC experiments at different heating rates to determine the enthalpy, in comparison with those determined with the actual value of the enthalpy of the PCM determined by a proven inverse method. A numerical model of a single–family house with a phase change material mortar is developed to evaluate the thermal comfort in the building. The results show that for free–running temperature, none of the enthalpy curve deduced directly from DSC can predict correctly the thermal behavior of the house and the thermal comfort. Moreover, the more the DSC heating rate and the more the discrepancy with the results from the reference inverse method.
  • Article
    Full-text available
    In recent years, demand response programs have proved useful in managing peak demand and meeting sustainability goals, enabling an efficient use of the smart grid. Heating, ventilation, and air conditioning (HVAC) loads in buildings constitute a large proportion of the total energy consumption of households, and accordingly, a flexible and efficient operation of these devices can aid power utilities in meeting load management objectives while reducing consumer’s electricity bills. With the emergence of promising new technologies, such as phase change materials (PCM), buildings can serve as a virtual thermal energy storage, which improves energy efficiency and also allows occupants to offer grid services like peak demand reduction. The objective of this paper is to establish the effectiveness of PCM as a demand response resource, demonstrating the extent to which it can be used for peak demand reduction. A wide range of scenarios are considered to investigate the impacts of geographical location, PCM melting point, duration of precooling and preheating, setting points of HVAC system, thickness and location of PCM, on the capability of the PCM in reducing or shifting the cooling and heating load. All simulations are performed using the EnergyPlus platform, examining typical residential buildings in five Australian cities: Brisbane, Sydney, Melbourne, Hobart and Perth. The simulation results showed a decrease in the HVAC demand in the buildings with PCM, in all cities, with the highest reductions observed in Hobart and Melbourne. The integration of a 20mm thick PCM in the roof, wall and floor of the building yielded a 21.8% and 16.7% reduction in annual HVAC demand in Hobart and Melbourne respectively, when compared to the building without PCM. However, this is with the assumption that the HVAC system is operating 24 hours a day for a whole year. The PCM-integrated building showed a shift in the HVAC demand in all cities except Perth. A shift by 9 minutes, 3 minutes, 60 minutes and 103 minutes was recorded in the cities of Brisbane, Sydney, Melbourne and Hobart respectively. The simulation results will be used in subsequent research to schedule the HVAC demand using a home energy management system.
  • Conference Paper
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    This paper assesses the opportunities of utilizing Phase Change Materials (PCMs) in building enclosure systems to improve energy performance and thermal comfort in buildings. The building sector continues to grow along with population growth, which will further increase energy consumption that is needed for space heating and cooling to provide thermal comfort for occupants. With many practical applications, PCMs are capable of storing and releasing significant amounts of energy by melting and solidifying at a given temperature and can play an important role as a thermal energy storage device by utilizing its high storage density and latent heat capacity. PCMs not only have the potential to reduce air conditioning energy consumption in residential and commercial buildings, but also have the potential to improve occupancy comfort by better maintaining desired surface temperatures. PCMs can be utilized to decrease the overall required energy of buildings by shifting part of the heating and cooling loads to off-peak hours when there is less energy demand within our utility grids. One of the potential applications for PCMs in buildings is to incorporate them within the building enclosure for energy storage. Our research investigates PCMs in an experimental study, from which we will extrapolate results to apply for residential application in different U.S. climate zones. The research extrapolation will be supported by simulation tools, which are capable of simulating PCMs in the building context. The study will also explore different factors contributing to other thermal performance criteria, such as the thermal conductivity and applicable temperature ranges of different PCMs. The results will be presented for better understanding of PCMs’ thermal behavior as well as demonstrating the applicability of using PCMs towards improving building performance and overall energy consumption in different climate contexts.
  • Article
    Full-text available
    To maintain comfort conditions in residential buildings along a full year period, the use of active systems is generally required to either supply heating or cooling. The heating and cooling demands strongly depend on the climatic conditions, type of building and occupants' behaviour. The overall annual energy consumption of the building can be reduced by the use of renewable energy sources and/or passive systems. The use of phase change materials (PCM) as passive systems in buildings enhances the thermal mass of the envelope, and reduces the indoor temperature fluctuations. As a consequence, the overall energy consumption of the building is generally lower as compared to the case when no PCM systems are used. The selection of the PCM melting temperature is a key issue to reduce the energy consumption of the buildings. The main focus of this study is to determine the optimum PCM melting temperature for passive heating and cooling according to different weather conditions. To achieve that, numerical simulations were carried out using EnergyPlus v8.4 coupled with GenOpt® v3.1.1 (a generic optimization software). A multi-family residential apartment was selected from ASHRAE Standard 90.1- 2013 prototype building model, and different climate conditions were considered to determine the optimum melting temperature (in the range from 20ºC to 26ºC) of the PCM contained in gypsum panels. The results confirm that the optimum melting temperature of the PCM strongly depends on the climatic conditions. In general, in cooling dominant climates the optimum PCM temperature is around 26ºC, while in heating dominant climates it is around 20ºC. Furthermore, the results show that an adequate selection of the PCM as passive system in building envelope can provide important energy savings for both heating dominant and cooling dominant regions.
  • Article
    The microencapsulation of linoleic (LinA), oleic, erucic, and palmitic acids (PAs) from styrene and divinylbenzene were studied by using the suspension-like polymerization technique. All materials exhibited a spherical shape, with a particle size between 166 and 416 μm. The phase change material (PCM) content decreased with the presence of double bonds in the fatty acid molecule. The thermal energy storage (TES) capacity of the microcapsules (MC) containing saturated PA was the highest (123.30 J g⁻¹). Whereas, the lowest TES capacity was observed for the LinA. TES capacity values from unsaturated fatty acid materials and the high particle yield indicated that these kinds of acids played two different roles, as PCM and also as monomers, in the radical polymerization processes. At high initiator concentrations, the unsaturated fatty acids were observed to react. This was confirmed by Fourier transform infrared where the peak assigned to the CC bond disappears in the spectrum of MC. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 135, 45970.
  • Article
    Full-text available
    Advantages, such as thermal storage improvement, are found when using PCMs (Phase Change Materials) in storage tanks. The inclusion of three different types of materials in a 60 ℓ test tank is studied. Two test methodologies were developed, and four tests were performed following each methodology. A thermal analysis is performed to check the thermal properties of each PCM. The distributions of the water temperatures inside the test tanks are evaluated by installing four Pt-100 sensors at different heights. A temperature recovery is observed after exposing the test tank to an energy demand. An energetic analysis that takes into account the energy due to the water temperature, the energy due to the PCM and the thermal loss to the ambient environment is also presented. The percentage of each PCM that remains in the liquid state after the energy demand is obtained.
  • Article
    The paper presents an idea for the enhancement of a building's thermal insulation component by adding into the structure a thin layer of a phase-change material (PCM). The proposed solution can be dedicated, for example, to an external partition of lightweight construction. The capacity for latent heat storage allowed it to stabilize the temperature inside the insulation layer in a daily cycle and to minimize the temperature difference between the internal and external surfaces. In this paper, different positions of a PCM layer in the thermal insulation of an external wall were analysed. The main goal of this work was to find the best position of the PCM layer, taking into account the indoor temperature and the meteorological conditions. The authors propose two parameters: the amount of stored energy and the dynamism of the charging/discharging processes. Taking into account large temperature fluctuations on the external surface during summer and winter, it was concluded that, for this specific case, the most appropriate solution would be an external position of the PCM with a melting temperature of 20°C.
  • Conference Paper
    Full-text available
    This study examined the effect on energy use and thermal comfort when combining microencapsulated phase change material (PCM) with radiant ceiling panels in a two-person office. The performance of the system was studied during the cooling season in the climates of Copenhagen, Denmark, and Rome, Italy, using a basic cooling strategy and a night cooling strategy. Negligible effect was observed in both Copenhagen and Rome with PCM integration using the basic cooling strategy with a constant cooling set point of 26°C (78.8°F). This caused nearly constant temperatures in the office, preventing full utilization of the PCM potential as charge and discharge of the PCM was averted. Application of night cooling strategy created more optimum temperature conditions for PCM activation with cooling of the office during night down to 23°C (73.4°F), enabling discharge of the PCM. This decreased the peak cooling power by 15% and increased the occupied hours in Category I of the European standard EN 16798-1 (EN 2016) by 8% in Copenhagen. Clearer effects were observed in Rome, decreasing the peak cooling power by 17% and increasing the occupied hours in Category I by 18%. These enhancements were achieved due to reduced operative temperature fluctuations caused by the construction thermal mass increase when integrating PCM. The study was based on both measured and theoretical properties of the ceiling panels, and greater enhancements of thermal indoor conditions were obtained using the theoretical panel specifications.
  • Conference Paper
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    Phase Change Materials (PCM), being able to supply dynamic thermal capacity due to their relatively high enthalpy of fusion, have largely shown a great potential for energy saving in buildings. Bio-compatible nanostructured shape-stabilized PCMs, with a specifically designed core-shell structure, already reported in a previous work, were studied here, with reference to lightweight constructions, carrying out dynamic simulations, adopting a multiparametric approach. Suitable figures of merit for thermal comfort indoor were adopted, with this aim.
  • Article
    Full-text available
    The article is focused on the research of the usage of modern accumulation technology. The proposed system is able to improve the thermal comfort of building interiors. That text depicts the technology, which uses a photovoltaics and other renewable energy sources for active heating and cooling. The bases of the presented technology are the phase change material and thermal energy storages. So, it passively improves the thermal capacity of the constructions of the buildings. Moreover, there is a possibility to use it for active heating and cooling. The technology contains thermoelectric assemblies, so, there is a very interesting possibility to store thermal energy with use of renewable energy sources (such as photovoltaic system) and thermoelectric coolers side by side. In the manuscript, there are shown measurements and results of the active operating modes of proposed technology. It was found the technology is able to work in active heating and cooling modes. It works quite well in active heating mode. On the other hand, thermoelectric cooling mode had a problem with overheating. In the end, the problem was solved and the cooling mode works. The measurements and results are described in the text.
  • Article
    Peak electric energy demand inflicts a great stress on the electric grid during the summer in the United States. With most years surpassing its previous year for the warmest year ever recorded, cooling requirements will continue to increase in the coming decades. Energy storage can potentially reduce electric demand. Among different technologies, phase change materials (PCMs) embedded in the building envelope have the potential to shift cooling energy demand away from peak hours. This study performs parametric analysis of PCMs in a relatively new home located in Phoenix, Arizona, USA. The analysis includes PCM location, PCM properties, precooling strategy, and an analysis of natural and forced convection models on the thermal behavior of the house. An extension of a standard forced convection model in EnergyPlus is used to represent the effects of a ceiling fan, which increases heat transfer at wall and ceiling surfaces and shortens the time needed to freeze or melt the phase change materials. Furthermore, the study discusses the use of appropriate setback temperatures to best utilize the PCMs. Overall, the optimal combination of PCMs, convection mode, and precooling schedule can completely shift cooling energy use during a three-hour demand period, producing maximum cost savings up to 29.4%, while increasing the occupant comfort.
  • Article
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    Vse pogosteje opažamo, da je v poletnih mesecih brez uporabe klimatskih naprav v novejših stavbah neprijetno vroče. Za to obstaja vrsta razlogov, pri čemer je eden izmed njih zagotovo nezadostna toplotna kapaciteta konstrukcijskih sklopov. Ena rešitev problema je uporaba fazno spremenljivih snovi, znanih tudi pod okrajšavo PCM (angleško Phase Change Material). Z njimi povečamo toplotno kapaciteto konstrukcijskega sklopa ob zanemarljivem povečanju njegove mase, s tem pa izboljšamo toplotno ugodje v notranjem okolju. Pregled literature je pokazal, da je v zadnjem desetletju močno naraslo število raziskav, ki obravnavajo lastnosti PCM, in število izdelkov s PCM za uporabo v stavbah. V prispevku smo z enostavnim izračunom pokazali, da lahko že s tanko plastjo PCM ustvarimo razmere, ki nam ugajajo v stavbah z večjo toplotno kapaciteto. Pri tem moramo paziti, da ima PCM tališče pri temperaturi, okoli katere se najpogosteje dnevno spreminja temperatura zraka. Predstavili smo nekaj primerov različnih vrst fazno spremenljivih snovi in primerov njihove uporabe v gradbenih proizvodih. Fazno spremenljive snovi imajo največji učinek, če jih vgradimo v sloj konstrukcije, ki je čim bližje notranjosti, saj imajo tako hiter odzivni čas, ki je kos dnevnim spremembam temperature. Pomembno je tudi, da jih ne obdamo z materiali nizke toplotne prevodnosti. Ključne besede: toplotna kapaciteta, fazno spremenljive snovi, PCM
  • Conference Paper
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    The energy storage is an important way to improve utilization of the alternative energy sources. The thermal stability of D-Mannitol to be applied as a phase change material (PCM) to store latent heat has been studied. D-Mannitol showed a strong decrease in melting enthalpy and melting temperature, when heated above its melting point at 170, 180, and 190 °C in a long-term heating measurement (5 days) under air atmosphere. These unstable conditions are due to the thermal oxidative degradation that takes place with the existence of oxygen. In order to inhibit the degradation reaction, antioxidants have been added to D-Mannitol. In addition, D-Mannitol samples were filled with argon gas to eliminate oxygen from the atmosphere that surrounds D-Mannitol. The tested samples were analyzed using differential scanning calorimetry (DSC) to measure the melting enthalpy and melting temperature. The treatment of antioxidants was not effective to inhibit the degradation reaction, but it showed a slower rate of degradation compared to pure D-Mannitol. Heating D-Mannitol for 115 hours in almost closed vials under argon atmosphere showed no evidence of an oxidation reaction, where it showed a lower tendency for a decrease in melting enthalpy.
  • Article
    This work presents an experimental research on the thermal properties of novel cementitious mortars incorporating microencapsulated Phase Change Materials intended to be used as the innermost layer in a precast radiant building component actively controlled by an integrated hydronic system. The characterization was developed in two steps: the first one focused on the effects of different fine aggregates and admixtures for a fixed PCM content and the second one on the effect of changing the amount of PCM. Results show that using silica aggregates and antifoaming admixture outperform the other options, producing mortars with statistically significant higher thermal conductivities, diffusivities and effusivities. Besides, increasing the amount of PCM significantly reduces conductivity and diffusivity, but the effusivity is practically invariant. This suggests that the mortar design has to be defined by predominantly focusing on diffusivity, in order to achieve appropriate heat penetration rates and activation times for an efficient system operation.
  • Conference Paper
    Phase Change Material (PCM) incorporated plasterboards (referred to as PCM-plasterboards in this paper) have been introduced to the lightweight wall construction industry due to their high thermal storage capacity, which improves the thermal performance. However, the fire performance of these wall systems must be investigated to ensure the safety of building structures in fire. The fire performance of lightweight wall systems mainly depends on the wall lining. Hence, the fire performance of PCM-plasterboard has been investigated using thermal characterisation, small-scale fire tests and Finite Element (FE) analyses in this research. This paper describes the details of this research and presents the results of PCM-plasterboards in comparison with commonly used, standard gypsum plasterboards. The thermal characteristics of PCM-plasterboard and standard gypsum plasterboard at elevated temperatures were determined based on thermal property tests whereas small-scale standard fire tests of the boards were conducted to evaluate the fire performance based on time-temperature profiles. FE models were then developed and analysed to simulate the performance of these boards exposed to standard fire conditions. Results from both experimental and FE studies show that lower Fire Resistance Levels (FRL) were obtained for PCM-plasterboards compared to gypsum plasterboards while importantly, PCM-plasterboard provided additional fuel to the fire.
  • Article
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    Energy efficiency improvement in building sector has become a real challenge in Morocco, especially in the northern region evolving a rapid urban growth. In this context, using the phase change materials (PCM) in the construction is presented as one of the promising solutions to enhance the thermal behaviour of building envelope. This work aims to investigate the thermal performance of a PCM integrated external wall and roof under the summer climate conditions of northern Morocco. Dynamic thermal characterization methodology is adopted through the calculation of decrement factor (DF) and time lag (TL) parameters. For that, a one-dimensional numerical model based on resistance–capacitance (RC) approach is developed and implicitly solved to simulate the heat transfer process through a wall/roof structure. The model is validated through a new small-scale experimental device. Different qualities of PCM, regarding its peak phase change temperature, have been evaluated. Moreover, the PCM layer emplacement within the wall/roof structure was evaluated considering two possible configurations. The obtained results show a significative enhancement of the thermal performance of different wall facades and roof through the use of the suitable PCM quality. An appropriate selection of PCM layer emplacement yields an evidenced enhancement in the case of the roof. As for the walls, the integration of PCM from the interior side increase the TL period but has a negative impact on the DF parameter.
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