Research

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18 pages, 2703 KiB

Open AccessArticle

Potential Benefits of Thermal Insulation in Public Buildings: Case of a University Building

by Reyhan Kaya and Semih Caglayan

Buildings 2023, 13(10), 2586; https://doi.org/10.3390/buildings13102586 - 13 Oct 2023

Viewed by 766

Global energy demand continues to rise due to advances in both developed and developing countries. Energy-efficient technologies and eco-friendly policies have been insufficient to counterbalance the increasing demand and, thus, the national strategies of many countries have been shaped by energy conservation considerations. [...] Read more.

Global energy demand continues to rise due to advances in both developed and developing countries. Energy-efficient technologies and eco-friendly policies have been insufficient to counterbalance the increasing demand and, thus, the national strategies of many countries have been shaped by energy conservation considerations. Buildings are responsible for more than one third of the global final energy consumption and the energy use in buildings is expected to grow more than 40% in the next 20 years. Even though the energy-efficient retrofits and thermal insulation of the building envelope have been widely studied in academia, the case of existing public buildings has been largely neglected. To fill the gap, this study investigates the thermal insulation of existing public buildings and unveils its potential benefits. An administrative building of a public university has been the subject of financial analysis to observe the feasibility of insulation applications and to identify the most feasible insulation application. The results reveal that (i) the most feasible application depends considerably on the financial scenarios and (ii) the feasibility of insulation applications is greatly influenced by the building geometry. This study contributes to the literature by demonstrating the feasibility of energy retrofits in an administrative public building and proposing an alternative way to achieve national energy efficiency objectives. Full article

(This article belongs to the Special Issue Energy Saving, Storage and Carbon Emission Mitigation Application for Buildings)

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18 pages, 3589 KiB

Open AccessArticle

Exergy Analysis of Transcritical CO₂ Air-Source Heat Pump with Honeycomb Gas Cooler

by Yujia Zhang, Zhihua Wang, Pengfei Zhang, Xin Jiang, Fenghao Wang, Chao Huan and Zhenjun Ma

Buildings 2023, 13(9), 2147; https://doi.org/10.3390/buildings13092147 - 24 Aug 2023

Cited by 1 | Viewed by 736

Abstract

In order to build an efficient and energy-saving CO₂ heat pump system and to improve the heat transfer efficiency of the gas cooler, a novel honeycomb gas cooler with a compact structure, high heat transfer efficiency, and high pressure-bearing capacity was proposed [...] Read more.

In order to build an efficient and energy-saving CO₂ heat pump system and to improve the heat transfer efficiency of the gas cooler, a novel honeycomb gas cooler with a compact structure, high heat transfer efficiency, and high pressure-bearing capacity was proposed in our previous work. To clarify the components in the system that need further optimization and to improve its performance, an exergy analysis of a transcritical CO₂ air-source heat pump system with the novel honeycomb gas cooler is studied in this paper. Based on the second law of thermodynamics, the exergy model of each component in the heat pump system is established, and the irreversible loss of each component is analyzed. In addition, the degree of energy loss of the honeycomb gas cooler is clarified, and the possibility and direction of system optimization are pointed out. The results show that the exergy efficiency of the system is 35.33% under nominal operating conditions, and there is a lot of room for improvement in its energy utilization. The three components with the largest exergy destruction percentage are the compressor, throttle valve, and evaporator in the order of 36.13%, 22.90%, and 19.51%, respectively. These components with high exergy destruction percentages are the main reasons for the large irreversible losses of the system. Full article

(This article belongs to the Special Issue Energy Saving, Storage and Carbon Emission Mitigation Application for Buildings)

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14 pages, 3858 KiB

Open AccessArticle

Thermal-Electric Modeling: A New Approach for Evaluating the Impact of Conservation Voltage Reduction on Cooling Equipment

by Harshit Varshney, Himanshu Jain and Ravi Tiwari

Buildings 2023, 13(5), 1287; https://doi.org/10.3390/buildings13051287 - 15 May 2023

Viewed by 752

Abstract

It has been suggested in the literature that by reducing the incoming voltage at a distribution feeder head or at the supply side of buildings, significant electricity savings can be achieved. This technique is called Conservation Voltage Reduction (CVR). Data-based analysis with and [...] Read more.

It has been suggested in the literature that by reducing the incoming voltage at a distribution feeder head or at the supply side of buildings, significant electricity savings can be achieved. This technique is called Conservation Voltage Reduction (CVR). Data-based analysis with and without CVR is primarily used to support such assertions, which does not explain the physics behind reduction in energy consumption with CVR. This paper presents a new approach for evaluating the impact of CVR on cooling equipment. In this approach, a thermal-electric model of the cooling process is developed in MATLAB’s SIMSCAPE toolbox that can be used to explain the physics behind energy reduction with CVR. This model includes an accurate model of a compressor coupled to an induction motor whose supply voltage can be varied to simulate CVR. Simulations performed using this model show that the Coefficient of Performance (COP) of cooling equipment improves with a reduction in supply voltage. However, the energy lost in the motor windings may nullify the impact of the improvement in the COP and render the CVR programs ineffective if the range of speed change is small over the allowable voltage change. The simulation results show an increase in energy consumption of 4% at 90% rated voltage compared to the energy consumed at the rated voltage. However, if variable frequency drives-based cooling equipment is appropriately controlled, it is possible to reduce their net energy consumption using CVR. Simulations performed keeping the ratio of the supply voltage and the frequency constant showed a reduction in energy consumption of 2.5% at 90% rated voltage compared to the energy consumed at the rated voltage. Thermal-electric modeling of building cooling equipment is, therefore, vital to accurately evaluating the benefits of CVR as smart, power electronics-based end-use equipment is globally adopted. Full article

(This article belongs to the Special Issue Energy Saving, Storage and Carbon Emission Mitigation Application for Buildings)

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27 pages, 5191 KiB

Open AccessArticle

Hot Water Generation for Domestic Use in Residential Buildings via PCM Integrated U-Tube Based Solar Thermal Collector: A 4-E Analysis

by Sudhir Kumar Pathak, V. V. Tyagi, K. Chopra, A. K. Pandey and Ahmet Sari

Buildings 2023, 13(5), 1212; https://doi.org/10.3390/buildings13051212 - 04 May 2023

Cited by 4 | Viewed by 1384

Abstract

In recent years, building energy consumption has increased every day due to population growth and an increased human desire for a healthy and pleasant lifestyle, and this is responsible for a crisis of energy shortages worldwide. Therefore, use of solar water heating (SWH) [...] Read more.

In recent years, building energy consumption has increased every day due to population growth and an increased human desire for a healthy and pleasant lifestyle, and this is responsible for a crisis of energy shortages worldwide. Therefore, use of solar water heating (SWH) systems in buildings for hot water demand is the prime need of the hour to maintain sustainability. The novelty of this work was in developing a phase change material (stearic acid)-filled U-tube based evacuated tube solar collector (collector A). In addition, another collector B, left without energy storage material, was considered a reference unit for comparing the energy and exergy outputs. The study’s main aim was to examine the energy, exergy, enviro- and exergoeconomic analysis of newly developed water heating systems. The findings of study revealed that the maximum daily energy outputs of collector A were found to be 85.86% (simultaneous mode) and 84.27% (midday charging mode) at a high mass flow rate (0.5 LPM), and exergy outputs were 19.41% and 21.35%, respectively, at a low flow rate. The thermal output of collector A was higher than that of collector B. The per liter cost of hot water produced from collector A with PCMs was found to be INR 0.1261 and INR 0.1276, respectively, under both modes, which is less compared with the electric geyser (0.325 INR). The levelized energy cost, net present worth, and the payback time of the developed collector A obtained were 4.61 INR/kWh, INR 49710, and 4.49 years (simultaneous), and 4.67 INR/kWh, INR 48130, and 4.64 years (mid-day charging), respectively. Furthermore, the amount of CO₂ mitigation from the energy and exergy perspective for collector A was found to be 24.30 and 23.76 tCO₂/lifetime and 5.31, 5.58 tCO₂/lifetime, respectively. Full article

(This article belongs to the Special Issue Energy Saving, Storage and Carbon Emission Mitigation Application for Buildings)

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16 pages, 4960 KiB

Open AccessArticle

Nano Engineered Paraffin-Based Phase Change Material for Building Thermal Management

by John Paul, Mahendran Samykano, Adarsh Kumar Pandey, Kumaran Kadirgama and Vineet Veer Tyagi

Buildings 2023, 13(4), 900; https://doi.org/10.3390/buildings13040900 - 29 Mar 2023

Cited by 9 | Viewed by 1775

Abstract

Thermal energy storage (TES) and harvesting is an effective technique for optimum building thermal management. Phase-change materials (PCMs) are commonly used for TES applications but are troubled by their degraded thermal conductivity. Recent research progress in latent heat energy storage using PCMs and [...] Read more.

Thermal energy storage (TES) and harvesting is an effective technique for optimum building thermal management. Phase-change materials (PCMs) are commonly used for TES applications but are troubled by their degraded thermal conductivity. Recent research progress in latent heat energy storage using PCMs and nano additives provides a viable solution for solar TES. A series of hybrid nano-enhanced phase change materials (HNePCMs) were prepared via two-step synthesis. Hybrid graphene–silver nanofillers were dispersed in commercial paraffin (melting point 25 ^°C) under different dispersion rates (0.1%, 0.3%, 0.5%). Different characterization techniques, e.g., FESEM, FT-IR, UV-VIS, TGA, XRD, DSC, and Tempos, were used in material characterization. A maximum enhancement of 6.7% in latent heat and 5% in heat storage efficiency was noted for nanocomposites with 0.3 wt% of additives. The nanocomposite with 0.3 Wt% showed great potential in shielding UV rays and showed a reduction of 6.5% in bandgap energy. Furthermore, the thermal conductivity of samples was boosted by a maximum of 90% (from 0.2 W/mK-0.39 W/mK) with 0.3 wt% dispersion of graphene–silver nanofillers. The thermophysical characterization results establish that the synthesized paraffin/graphene–silver hybrid nanocomposites are well suited for building thermal management. Full article

(This article belongs to the Special Issue Energy Saving, Storage and Carbon Emission Mitigation Application for Buildings)

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19 pages, 6408 KiB

Open AccessArticle

Optimizing PCM Integrated Wall and Roof for Energy Saving in Building under Various Climatic Conditions of Mediterranean Region

by Sana Dardouri, Ekrem Tunçbilek, Othmen Khaldi, Müslüm Arıcı and Jalila Sghaier

Buildings 2023, 13(3), 806; https://doi.org/10.3390/buildings13030806 - 18 Mar 2023

Cited by 9 | Viewed by 2725

Abstract

Energy conservation in buildings has been the focus of many studies since nearly one-third of global energy consumption is due to buildings. Phase change material (PCM) technology promises to be an attractive solution for energy saving in buildings since it is a passive [...] Read more.

Energy conservation in buildings has been the focus of many studies since nearly one-third of global energy consumption is due to buildings. Phase change material (PCM) technology promises to be an attractive solution for energy saving in buildings since it is a passive and effective technology, as demonstrated in the literature. Therefore, this study focuses on the energy-saving performance of PCM-integrated buildings located in a Mediterranean climate to reveal their energy-saving potential. PCM is integrated both in external or internal south walls and roofs of buildings under four different climatic conditions. EnergyPlus, which is a well-known building simulation software, is adopted for building thermal analyses. The effects of melting temperature, location of PCM layer in the wall, thickness of PCM layer, type of envelope (wall or roof), and PCM double-layer system in the wall are investigated. The corresponding energy savings and CO₂ emission reductions are obtained for the considered cases. The results showed that up to 41.6% reduction in energy demand can be obtained depending on the PCM application. Besides, PCM with a low melting temperature (21 °C) favored heating energy savings, while PCM with a high melting temperature (29 °C) favored cooling energy savings. Moreover, the double-layer PCM system provided higher energy savings than the single-layer PCM system, especially in warm and arid regions (Sousse and Tozeur). Full article

(This article belongs to the Special Issue Energy Saving, Storage and Carbon Emission Mitigation Application for Buildings)

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22 pages, 6963 KiB

Open AccessArticle

Recycling Textile Waste to Enhance Building Thermal Insulation and Reduce Carbon Emissions: Experimentation and Model-Based Dynamic Assessment

by Rabeb Ayed, Salwa Bouadila, Safa Skouri, Laura Boquera, Luisa F. Cabeza and Mariem Lazaar

Buildings 2023, 13(2), 535; https://doi.org/10.3390/buildings13020535 - 15 Feb 2023

Cited by 6 | Viewed by 3201

Abstract

By enhancing the thermal properties of cement-based building materials, energy consumption and carbon dioxide (CO₂) emissions related to space conditioning in buildings can be alleviated. This study aims to present cement-based composites reinforced by textile fibers for application in building and [...] Read more.

By enhancing the thermal properties of cement-based building materials, energy consumption and carbon dioxide (CO₂) emissions related to space conditioning in buildings can be alleviated. This study aims to present cement-based composites reinforced by textile fibers for application in building and construction. Several lightweight coating mortars were produced by partially replacing the sand in the mix with different percentages of textile waste. Mechanical and thermal characterizations of the reinforced cementitious composites were performed. The results showed that the thermal conductivity of cementitious compounds decreased as the proportion of reinforcing material in the mixture increased. In terms of mechanical properties, the textile slightly reduced the compressive strength of cementitious mortar, while it improved the flexural strength. A numerical study was then performed to derive the actual impact of these reinforced materials on the thermal behavior of a building element using COMSOL Multiphysics. Numerous configurations of walls coated with different mortar mixtures were studied. The results showed that coating both sides of a building wall with 20 mm of textile-reinforced mortar reduced the internal temperature by 1.5 °C. Thus, the application of these thermally improved mortars as coating mortars appears to be a relevant solution to enhance the thermal performance of buildings. Full article

(This article belongs to the Special Issue Energy Saving, Storage and Carbon Emission Mitigation Application for Buildings)

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14 pages, 4459 KiB

Open AccessArticle

Investigation of the Effect of Air Layer Thickness on the Thermal Performance of the PCM Integrated Roof

by Dnyandip K. Bhamare, Manish K. Rathod, Jyotirmay Banerjee and Müslüm Arıcı

Buildings 2023, 13(2), 488; https://doi.org/10.3390/buildings13020488 - 10 Feb 2023

Cited by 2 | Viewed by 1597

Abstract

Recently, Phase Change Materials (PCM) have become more prevalent in improving buildings’ thermal management. The relative location of the PCM layer is a valuable measure for assessing the thermal performance of building envelopes, in addition to meteorological circumstances and PCM qualities. The optimum [...] Read more.

Recently, Phase Change Materials (PCM) have become more prevalent in improving buildings’ thermal management. The relative location of the PCM layer is a valuable measure for assessing the thermal performance of building envelopes, in addition to meteorological circumstances and PCM qualities. The optimum air layers between the PCM layer and roof may significantly reduce energy consumption in buildings. In this regard, the influence of air gap layer thickness on the thermal performance of a PCM (HS 29) integrated roof of the test room is investigated experimentally. Experiments are carried out for an unconditioned test room located on the terrace of a laboratory in Surat, India, considering various air layer thickness values (0, 2, 4, and 6 cm) and a fixed PCM layer thickness. Different configurations within the research, including no- PCM and PCM with 0, 2, 4, and 6 cm air layer thickness, are investigated for the effects of diurnal change in room temperature. Results are evaluated based on the peak value, valley value temperatures of different roof layers, and an index (MKR, Measure of Key Response). It is observed that the maximum temperature difference between the PCM-integrated test room and the non-PCM test room is 4 °C to 7 °C. Results showed that, with a higher MKR index of 8.83, a PCM-integrated roof with a 2 cm air layer thickness could reduce the diurnal room temperature variations compared with the non-PCM test room. This conclusion from the current research demonstrates the significance of an air layer provided between the PCM layer and the roof of the building. Full article

(This article belongs to the Special Issue Energy Saving, Storage and Carbon Emission Mitigation Application for Buildings)

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Review

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26 pages, 8504 KiB

Open AccessReview

An Overview of Emerging and Sustainable Technologies for Increased Energy Efficiency and Carbon Emission Mitigation in Buildings

by Zhenjun Ma, Muhammad Bilal Awan, Menglong Lu, Shengteng Li, Muhammad Shahbaz Aziz, Xinlei Zhou, Han Du, Xinyi Sha and Yixuan Li

Buildings 2023, 13(10), 2658; https://doi.org/10.3390/buildings13102658 - 22 Oct 2023

Cited by 2 | Viewed by 2371

Abstract

The building sector accounts for a significant proportion of global energy usage and carbon dioxide emissions. It is important to explore technological advances to curtail building energy usage to support the transition to a sustainable energy future. This study provides an overview of [...] Read more.

The building sector accounts for a significant proportion of global energy usage and carbon dioxide emissions. It is important to explore technological advances to curtail building energy usage to support the transition to a sustainable energy future. This study provides an overview of emerging and sustainable technologies and strategies that can assist in achieving building decarbonization. The main technologies reviewed include uncertainty-based design, renewable integration in buildings, thermal energy storage, heat pump technologies, thermal energy sharing, building retrofits, demand flexibility, data-driven modeling, improved control, and grid-buildings integrated control. The review results indicated that these emerging and sustainable technologies showed great potential in reducing building operating costs and carbon footprint. The synergy among these technologies is an important area that should be explored. An appropriate combination of these technologies can help achieve grid-responsive net-zero energy buildings, which is anticipated to be one of the best options to simultaneously reduce building emissions, energy consumption, and operating costs, as well as support dynamic supply conditions of the renewable energy-powered grids. However, to unlock the full potential of these technologies, collaborative efforts between different stakeholders are needed to facilitate their integration and deployment on a larger and wider scale. Full article

(This article belongs to the Special Issue Energy Saving, Storage and Carbon Emission Mitigation Application for Buildings)

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32 pages, 5074 KiB

Open AccessReview

Hybrid Photovoltaic Thermal Systems: Present and Future Feasibilities for Industrial and Building Applications

by Mahendran Samykano

Buildings 2023, 13(8), 1950; https://doi.org/10.3390/buildings13081950 - 31 Jul 2023

Cited by 5 | Viewed by 1881

Abstract

The growing demands of modern life, industrialization, and technological progress have significantly increased energy requirements. However, this heightened need for energy has raised concerns about its impact on the environment and the rising costs associated with it. Therefore, the engineering sector is actively [...] Read more.

The growing demands of modern life, industrialization, and technological progress have significantly increased energy requirements. However, this heightened need for energy has raised concerns about its impact on the environment and the rising costs associated with it. Therefore, the engineering sector is actively seeking sustainable and cost-effective energy solutions. Among the promising innovations in solving the problem is the photovoltaic thermal system (PVT), which aims to capture electrical and thermal energy from solar radiation. Despite its potential, the application of PVT systems is currently limited due to the unpredictable nature of solar energy and the absence of efficient thermal energy storage capabilities. To address these challenges, researchers have explored the use of phase change materials and nano-improved phase change materials (NEPCMs) to optimize energy extraction from solar systems. By incorporating these materials, the PVT system can maximize energy utilization. This article provides a comprehensive overview of the potential applications of PVT techniques in both industrial and building settings. It also offers a detailed assessment of their commercial and environmental aspects. The research findings highlight several advantages of PVT systems, including reduced electricity consumption, efficient utilization of cooling and heating loads during off-peak periods, improved temperature stability, and enhanced thermal comfort. Furthermore, the integration of NEPCMs in PVT systems has demonstrated superior thermal performance, enabling 8.3% more heat energy storage during charging and 25.1% more heat energy release during discharging. Additionally, the implementation of solar-assisted combined heating and power systems showed the potential to prevent the emission of 911 tons of CO₂ per year compared to conventional PV systems. These systems offer a promising pathway towards mitigating environmental impacts while meeting energy demands. Overall, this review article serves as a valuable resource for fellow researchers by providing detailed insights into the viability of PVT systems for various applications in the industrial and building sectors. Full article

(This article belongs to the Special Issue Energy Saving, Storage and Carbon Emission Mitigation Application for Buildings)

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51 pages, 7703 KiB

Open AccessReview

Climate Zoning for Buildings: From Basic to Advanced Methods—A Review of the Scientific Literature

by Alexey Remizov, Shazim Ali Memon and Jong R. Kim

Buildings 2023, 13(3), 694; https://doi.org/10.3390/buildings13030694 - 06 Mar 2023

Cited by 4 | Viewed by 2264

Abstract

Understanding the link between the energy-efficiency of buildings and climatic conditions can improve the design of energy-efficient housing. Due to global climate change and growing requirements for building energy-efficiency, the number of publications on climate zoning for buildings has grown over the last [...] Read more.

Understanding the link between the energy-efficiency of buildings and climatic conditions can improve the design of energy-efficient housing. Due to global climate change and growing requirements for building energy-efficiency, the number of publications on climate zoning for buildings has grown over the last 20 years. This review attempted to give the reader an up-to-date assessment of the scientific literature in the field of climate mapping for buildings on a global and national scale, filling in the gaps of previous works and focusing on details that were not presented before. There were 105 scientific sources examined. The most dominant climate zoning variables were thoroughly analyzed. A clear categorization of climate zoning methods with specific criteria was shown. The most used methods were evaluated, emphasizing their similarities and differences, as well as their essential components and advantages. The main literature review was supported with bibliometric and bibliographic analysis. The existence of many climate zoning methods can be an indicator of the lack of agreement on the most effective strategy. A tendency has been established for the popularization among scientists of methods based on machine learning and building energy simulations, which are relatively easy to use and have proven to be the most reliable climate zoning methods. A transformation is emerging by shifting from a climate-based to a building performance-based climate zoning approach. Full article

(This article belongs to the Special Issue Energy Saving, Storage and Carbon Emission Mitigation Application for Buildings)

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