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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.

The significant energy consumption and contribution to greenhouse gas emissions by the construction sector need careful attention to explore innovative sustainable solutions for improving the energy efficiency and thermal comfort of building envelopes. The integration of phase-change materials (PCMs) into building commodities is a favorable technology for minimizing energy consumption and enhancing thermal performance. This review paper covers the impact of PCM incorporation into construction materials, such as walls, roofs, and glazing units. Additionally, it examines different embedding techniques like direct incorporation, immersion, macro and micro-encapsulation, and form and shape-stable PCM. Factors affecting the thermal performance of PCM-integrated buildings, including melting temperature, thickness, position, volumetric change, vapor pressure, density, optical properties, latent heat, thermal conductivity, chemical stability, and climate conditions, are elaborated. Furthermore, the latest experimental and numerical simulations, as well as modeling techniques, evident from case studies, are investigated. Ultimately, the advantages of PCM integration, including energy savings, peak load reduction, improvement in interior comfort, and reduced heating, ventilation, and air-conditioning dependence, are explained alongside the limitations. Finally, the recent progress and future potential of PCM-integrated construction materials are discussed, focusing on innovations in this field, addressing the status of policies in line with the United Nations Sustainable Development Goals, and outlining research potential for the future.

Radiative cooling has emerged as a promising technique for reducing energy consumption in building thermal management due to its passive cooling property and no external energy requirement. Despite significant advances, scalable production of artificial photonic radiators with periodic structures, environmental stability, high radiative cooling performance, and economic applicability is still challenging in most state‐of‐the‐art radiative coolers. Rational structure and materials design are essential to promote daytime sunlight reflectance while maintaining a high emissivity within the atmospheric window (8–13 µm). In this work, inspired from the unique hair structure of heat‐resistant organisms, a biomimetic micro‐pyramid shaped structure model is analyzed. By mimicking the intricate design with a silicon template, a radiative cooling film containing specialized micro‐pyramid structure is fabricated by integrating high dielectric constant materials with polymers and receiving PVDF coating. The resulting film boasts a solar reflectance of 97.3% and an exceeding 98% infrared light emission within the atmospheric window. In addition, silicon rubber endows this membrane with strong tensile and rebound properties while surficial hydrophobicity protects the membrane from dust infestation. Considering the manufacturing simplicity and cost‐effectiveness, this method shows great potential for mass production, shedding light on building thermal management. Taking inspirations from the special surface structure of natural heat‐resistant organisms, a biomimetic micro‐pyramid‐shaped radiative cooling film is fabricated by integrating high dielectric constant materials with polymers. The resulting film boasts a solar reflectance of 97.3%, an exceeding 98% infrared light emission within the atmospheric window and achieves an average temperature drop of 7.3 °C for the coated device under sunlight irradiation.

Daytime passive radiative cooling (DPRC) has remained a challenge over the past decades due to the necessity of precisely defined materials with a significantly high emissivity of thermal radiation within the atmospheric transparent window wavelength range (8–13 μm) as well as high reflectivity in the solar spectrum (0.2–3 μm). Fortunately, recent advances and technological improvements in nanoscience and metamaterials are making it possible to create diverse metamaterials. This enables the production of DPRC in direct solar irradiation. The development of a material that is appropriate for effective DPRC is also a noteworthy development in this field of technology. This review gives a thorough introduction and discussion of the fundamental ideas, as well as the state-of-the-art and current trends in passive radiative cooling, and describes the cutting-edge materials and various photonic radiator structures that are useful in enhancing net cooling performance. This work also addresses a novel skylight window that offers passive cooling developed at the Åbo Akademi (ÅA) University, Finland. In conclusion, nanomaterials and nanoparticle-based coatings are preferred over all other approaches for commercialization in the future because of their low cost, the ability for large-scale production, simplicity in fabrication, and great potential for further increasing cooling performance.

Energy and environmental problems have attracted attention worldwide. Energy consumption in residential sectors accounts for a large percentage of total consumption. Several retrofit schemes, which insulate building envelopes to increase energy efficiency, have been adapted to address residential energy problems. However, these schemes often fail to balance the installment cost with savings from the retrofits. To maximize the benefit, selecting houses with low thermal performance by a cost-effective method is inevitable. Therefore, an accurate, low-cost, and undemanding housing assessment method is required. This paper proposes a thermal performance assessment method for residential housing. The proposed method enables assessments under the existing conditions of residential housings and only requires a simple and affordable monitoring system of power meters for an air conditioner (AC), simple sensors (three thermometers at most), a BLE beacon, and smartphone application. The proposed method is evaluated thoroughly by using both simulation and experimental data. Analysis of estimation errors is also conducted. Our method shows that the accuracy achieved with the proposed three-room model is 9.8% (relative error) for the simulation data. Assessments on the experimental data also show that our proposed method achieved Ua value estimations using a low-cost system, satisfying the requirements of housing assessments for retrofits.

Radiative cooling is an emerging cooling technology that can passively release heat to the environment. To obtain a subambient cooling effect during the daytime, chemically engineered structural materials are widely explored to simultaneously reject sunlight and preserve strong thermal emission. However, many previously reported fabrication processes involve hazardous chemicals, which can hinder a material's ability to be mass produced. In order to eliminate the hazardous chemicals used in the fabrication of previous works, this article reports a white polydimethylsiloxane (PDMS) sponge fabricated by a sustainable process using microsugar templates. By substituting the chemicals for sugar, the manufacturing procedure produces zero toxic waste and can also be endlessly recycled via methods widely used in the sugar industry. The obtained porous PDMS exhibits strong visible scattering and thermal emission, resulting in an efficient temperature reduction of 4.6 °C and cooling power of 43 W m−2 under direct solar irradiation. In addition, due to the air‐filled voids within the PDMS sponge, its thermal conductivity remains low at 0.06 W (m K)−1. This unique combination of radiative cooling and thermal insulation properties can efficiently suppress the heat exchange with the solar‐heated rooftop or the environment, representing a promising future for new energy‐efficient building envelope material. This work presents a porous polydimethylsiloxane (PDMS) sponge fabricated using a sustainable and inexpensive sugar‐template casting method. The obtained porous PDMS sponge exhibits efficient radiative cooling performance and excellent thermal isolation. This combined feature can suppress the heat exchange from warm outdoor environment, indicating its application for future energy‐efficient building envelope materials.

•Review of the use of DT for thermal comfort (TC) & energy consumption in buildings.•Technologies were examined in creating DT for TC & energy optimization.•Prediction of energy consumption using ANN, AI, deep neural networks, and YOLOv4.•Recommends the use of XR such as AR, VR, and MR for interactive experiences.•Wider adoption of DT to improve user comfort, behavioural action&energy prediction. In recent years, the integration of digital technologies has grown rapidly in the field of thermal comfort and energy efficiency for buildings. The concept of a digital twin, incorporating multiple digital technologies, has gained increasing attention. The literature lacks a review of the digital twin concept in thermal comfort and energy consumption for existing buildings. This paper conducts a review of the current state-of-the-art in digital twin (DT) technology for thermal comfort/ energy consumption in buildings. The review employs a scientometric approach and examines various technologies used in creating DTs and a systematic analysis of the methods, technologies, algorithms, and approaches used in digital twin experiments. The results show a growing number of studies in this area, with a focus on thermal comfort monitoring, visualization, tracking, energy management, prediction, and optimization for existing buildings. Furthermore, the prediction of energy consumption using algorithms such as Artificial Neural Networks (ANN), Artificial Intelligence (AI), deep neural networks, and YOLOv4 have been used in buildings. However, the wider adoption of a DT that can facilitate occupants, and thermal sensations, enhance human-centered solutions, and improve energy prediction levels are necessary. There is a need for further international collaboration to expand the studies on digital twins for thermal comfort and energy efficiency. The review highlights the limitations and areas of improvement, such as the limited adoption of sensors for environmental measures, the need for more focus on the subjective perception of occupants, and the need for more comparative studies of algorithms for predicting energy consumption. Further studies can be conducted in areas such as understanding occupant psychological responses/behaviors to comfort in the digital world. This will enhance a more consolidated and robust validation for building performance. [Display omitted]

HighlightsHighly porous aerogel with longitudinally aligned channels and whisker-like ligaments is constructed by solvent-assisted unidirectional freezing.The thermal insulation and solar reflection capabilities of the composite aerogel reach a state-of-the-art level.The composite aerogel capable of infrared stealth and temperature preservation presents great potential for application in energy-saving buildings.With the mandate of worldwide carbon neutralization, pursuing comfortable living environment while consuming less energy is an enticing and unavoidable choice. Novel composite aerogels with super thermal insulation and high sunlight reflection are developed for energy-efficient buildings. A solvent-assisted freeze-casting strategy is used to produce boron nitride nanosheet/polyvinyl alcohol (BNNS/PVA) composite aerogels with a tailored alignment channel structure. The effects of acetone and BNNS fillers on microstructures and multifunctional properties of aerogels are investigated. The acetone in the PVA suspension enlarges the cell walls to suppress the shrinkage, giving rise to a lower density and a higher porosity, accompanied with much diminished heat conduction throughout the whole product. The addition of BNNS fillers creates whiskers in place of disconnected transverse ligaments between adjacent cell walls, further ameliorating the thermal insulation transverse to the cell wall direction. The resultant BNNS/PVA aerogel delivers an ultralow thermal conductivity of 23.5 mW m−1 K−1 in the transverse direction. The superinsulating aerogel presents both an infrared stealthy capability and a high solar reflectance of 93.8% over the whole sunlight wavelength, far outperforming commercial expanded polystyrene foams with reflective coatings. The anisotropic BNNS/PVA composite aerogel presents great potential for application in energy-saving buildings.

Phase change materials (PCMs) have emerged as promising solutions for improving thermal management in residential buildings by enhancing thermal storage capacity and reducing energy consumption. This article aims to provide a comprehensive analysis of the application of PCMs in residential construction, focusing on their thermal properties, benefits, and limitations. A systematic literature review was conducted following PRISMA guidelines, primarily covering studies published between 2015 and 2025. However, key studies published outside this period were also considered due to their relevance and significant contribution to the understanding of PCM performance and application. This analysis explores key parameters affecting PCM performance, including phase transition temperature, thermal conductivity, and material stability. The results highlight that optimized PCM integration can reduce energy consumption by up to 30% and improve indoor thermal comfort. However, challenges such as low thermal conductivity and phase separation still limit their large-scale adoption. The findings provide insights into the advantages and barriers associated with PCM-based systems and propose strategies to enhance their performance, including the use of nanocomposites and improved encapsulation techniques.

To maintain comfortable indoor conditions, buildings consume ~40% of the energy generated globally. In terms of passively isolating building interiors from cold or hot outdoors, windows and skylights are the least-efficient parts of the building envelope because achieving simultaneously high transparency and thermal insulation of glazing remains a challenge. Here we describe highly transparent aerogels fabricated from cellulose, an Earth-abundant biopolymer, by utilizing approaches such as colloidal self assembly and procedures compatible with roll-to-roll processing. The aerogels have visible-range light transmission of 97–99% (better than glass), haze of ~1% and thermal conductivity lower than that of still air. These lightweight materials can be used as panes inside multi-pane insulating glass units and to retrofit existing windows. We demonstrate how aerogels boost energy efficiency and may enable advanced technical solutions for insulating glass units, skylights, daylighting and facade glazing, potentially increasing the role of glazing in building envelopes. Windows are one of the least energy efficient parts of the building envelope because of poor thermal insulation. Abraham et al. develop a cellulose-based aerogel as a thermal barrier for windows that retains their optical properties.