Mortar composites incorporating VO₂/MWCNT solid–solid nanophase change material for passive indoor temperature regulation

Abstract

Phase change materials (PCMs) have emerged as promising materials for improving the thermal performance of building envelopes. In this study, a solid–solid nanophase change material (nanoPCM) composed of vanadium dioxide (VO₂) and multiwalled carbon nanotubes (MWCNTs) was synthesized and incorporated into cement mortar at contents ranging from 0.5 to 3 wt%. The effects of nanoPCM incorporation on hydration behavior, microstructure, compressive strength, thermophysical properties (specific heat capacity, thermal conductivity, diffusivity and effusivity), thermal regulation capacity and energy saving were investigated. The results revealed a synergistic interaction between VO₂ and MWCNTs, reducing the phase transition temperature (Tc) from 72.41 °C to 63.73 °C while increasing thermal conductivity by approximately 3.5 times. The incorporation of nanoPCM slightly increased mortar density and improved long-term compressive strength, with a maximum increase of 24.5% observed at 1 wt% nanoPCM addition. Hydration calorimetry revealed that nanoPCM delayed early-age hydration kinetics without suppressing the overall hydration process. In the mortar composites, nanoPCM incorporation reduced thermal conductivity, diffusivity and effusivity with a slight decrease in the specific heat capacity, resulting in enhanced thermal inertia and delayed heat transfer. Thermal regulation tests confirmed a reduction in temperature fluctuations, while building energy simulations demonstrated annual energy savings of up to 2.23%, depending on climatic conditions. These findings demonstrate that tailoring the thermophysical properties of cementitious materials through VO₂/MWCNT solid–solid nanoPCM represents an effective strategy for improving passive indoor temperature regulation and reducing building energy demand without compromising mechanical performance.

1 Introduction

Improving the energy efficiency of buildings has become a global priority due to the increasing demand for energy and the need to reduce greenhouse gas emissions associated with the built environment (Hu et al., 2026). Consequently, the transition toward nearly zero-emission buildings has intensified the search for low-carbon construction materials capable of enhancing the thermal performance of building envelopes while reducing operational energy consumption. Passive thermal regulation strategies that reduce heat transfer through building envelopes have attracted considerable attention as an effective approach to decrease operational energy demand while improving building resilience and sustainability (Ghamari et al., 2024).

Among the different passive thermal-management technologies, phase change materials (PCMs) have emerged as promising candidates due to their ability to absorb, store and release thermal energy during phase transitions (Togun et al., 2025). The incorporation of PCMs into cementitious materials has been extensively investigated, demonstrating that PCM-modified cementitious composites can improve the thermal performance of building envelopes and contribute to energy savings under different climatic conditions (Ghamari et al., 2024; Hu et al., 2026). However, most investigations have focused on solid–liquid phase transition PCMs which, despite their high latent heat storage capacity, often suffer from leakage during phase transition and therefore require encapsulation or shape-stabilization treatments prior to incorporation into construction materials (Ghamari et al., 2024; Hu et al., 2026).

Another important limitation of PCMs is their inherently low thermal conductivity, which restricts the rate of heat absorption and release during charging and discharging processes. This limitation can reduce the effective utilization of the stored thermal energy and slow the thermal response of PCM-based building materials. Furthermore, encapsulation and shape-stabilization strategies frequently introduce additional thermal resistance between the PCM and the surrounding cementitious matrix, reducing the efficiency of heat transfer toward active PCM domains (Su et al., 2015). As a result, relatively high PCM loadings, commonly exceeding 10 wt% in cementitious composites, are often required to achieve significant thermal-regulation effects and measurable reductions in building energy consumption (Liu et al., 2023; Lygerakis et al., 2025). To improve heat transfer efficiency carbon-based materials such as carbon nanotubes, graphene and other carbonaceous materials have been incorporated into PCMs, improving thermal and energy performance in cementitious materials (Jin et al., 2021; Aodkeng et al., 2022; Xiong et al., 2022; Kim et al., 2024). These studies demonstrated that carbon networks facilitate heat transfer toward active PCM domains. Nevertheless, these investigations have been almost exclusively focused on solid–liquid PCMs, while the potential of carbon-enhanced solid–solid PCM systems for cementitious applications remains largely unexplored.

Solid–solid PCMs represent an attractive alternative for construction materials because they undergo phase transitions without liquid formation, thereby eliminating leakage problems while maintaining dimensional stability. Among them, VO₂ has attracted increasing interest owing to its reversible thermally induced phase transition and thermal energy storage capability (Baba et al., 2021). The incorporation of a VO₂/MWCNT nanoPCM into gypsum composites has recently demonstrated promising potential for passive thermal regulation, highlighting the benefits of combining the thermal energy storage capability of VO₂ with the enhanced heat-transfer efficiency provided by MWCNTs (Figueroa-Torres et al., 2025). However, the study was focused on gypsum matrices containing 1 wt% of VO₂/MWCNT and on demonstrating the feasibility of direct nanoPCM incorporation for thermoregulation. In contrast, the behavior of this VO₂/MWCNT nanoPCM in Portland cement systems remains unexplored, despite the fundamental differences in hydration chemistry, microstructural evolution and strength development compared to gypsum. Moreover, the effects of VO₂/MWCNT dosages exceeding 1 wt% on cement hydration kinetics, thermophysical properties and building energy performance have not yet been systematically investigated.

Therefore, this study investigates the incorporation of a VO₂/MWCNT solid–solid nanoPCM into cement mortar composites at dosages ranging from 0.5 to 3 wt%. Particular attention was given to evaluate how increasing VO₂/MWCNT content influences cement hydration, microstructure, mechanical performance, thermophysical properties and thermal regulation capacity. Finally, the thermal performance of these nanoPCM-modified mortars was assessed through building energy simulations under different climatic conditions, considering their application as exterior cementitious coatings for energy-efficient buildings.

2 Materials and methods

2.1 Materials

In this study, Composite Portland Cement (CPC) 30R supplied by CEMEX, was used as the binder and standard #4 limestone sand was employed as fine aggregate. Vanadium dioxide (VO₂) was acquired from Alfa Aesar™ with 99% purity. Hydroxyl functionalized MWCNTs (OH-MWCNTs) were purchased from US Research Nanomaterials, with an outer diameter of 20–40 nm and lengths ranging from 10 to 30 μm, and a purity of 95%. Ethylene glycol (C₂H₆O₂) with 99.91% of purity and distilled water were acquired from CTR Scientific. The mineralogical chemical composition of Portland cement is given in Table 1.

2.2 Preparation of the nanophase change material

The nanophase change material VO₂/MWCNT was synthesized using a wet impregnation method with a VO₂-to-MWCNT mass ratio of 95:5, deliberately selected to maintain the heat storage capacity provided by VO₂ while enhancing the thermal conductivity of the system through the incorporation of MWCNTs. The required amounts of nanomaterials were first dispersed in isopropanol at a concentration of 10 mg/mL and sonicated in an ultrasonic bath for 1 h to promote homogeneous dispersion. Subsequently, isopropanol was slowly evaporated at 80 °C under continuous magnetic stirring until a dry powder was obtained. The resulting nanocomposite was then thermally treated in air at 300 °C for 2 h, using a heating rate of 10 °C/min to eliminate residual isopropanol and enhance the interfacial contact between VO₂ nanoparticles and MWCNTs. Finally, the samples were cooled to room temperature.

2.3 NanoPCM-mortar composites preparation

Five rendering mortar composites were prepared, with one without VO₂/MWCNT serving as the control sample and identified as REF. The other four were prepared by incorporating 0.5, 1, 2 and 3 wt% of the VO₂/MWCNT nanoPCM relative to the cement mass. All mixtures were prepared using a fixed water-to-binder ratio of 0.74 to provide the workability required for rendering mortars, and a sand-to-binder ratio of 3:1. Ethylene glycol was used as a dispersing agent for the nanoPCM at a fixed dosage of 1 vol% of the mixing water.

To ensure adequate dispersion of the VO₂/MWCNT nanoPCM, the required amount of nanoPCM and ethylene glycol was added to the mixing water and magnetically stirred for 10 min. Subsequently, the mixture was subjected to ultrasonication for 1 h. The resulting suspension was then used to prepare the mortars following ASTM C305. Fresh mortars were cast into cubic molds (50 × 50 × 50 mm) for compressive strength testing and cylindrical molds with a diameter of 2 cm for microstructural characterization. After casting, the samples were covered with plastic sheets to prevent water evaporation and stored at ambient temperature. After 24 h, the samples were demolded and cured under controlled conditions for 3, 7 and 28 days.

2.4 Characterization of the samples

The chemical composition of the CPC 30R cement was analyzed by X-ray fluorescence (XRF) using a PANalytical Epsilon 3-XL spectrometer operated under nitrogen atmosphere to avoid sample oxidation. The crystalline phases presented in the samples were determined by X-ray diffraction (XRD) using a PANalytical Empyrean diffractometer. The measurements were made using Cu Kα radiation with a wavelength of 1.544 Å, in a 2θ range from 5 ° to 65 °, employing a step size of 0.02 °. Microstructural observations were performed using Field Emission Scanning Electron Microscopy (FESEM) and vanadium elemental mapping was performed using EDS detector coupled to the microscope. Prior to analysis, samples were coated with a thin gold-palladium layer to improve surface conductivity due to the non-conductive nature of the cementitious samples.

The thermophysical properties of the VO₂ nanoparticles, MWCNTs and VO₂/MWCNT nanoPCM were determined by differential scanning calorimetry (DSC) TA Instruments SCS Q200. Measurements were performed over a temperature range of 30 °C–100 °C with a heating/cooling rate of 5 °C/min under a nitrogen atmosphere. The phase transition temperature (Tc) was determined as the mean value of the endothermic and exothermic peaks during heating and cooling, respectively. The latent heats of the heating and cooling processes were obtained by integrating the corresponding DSC peak areas.

The effect of nanoPCM incorporation on the hydration kinetics of the mortar composites was investigated using isothermal calorimetry. Measurements were conducted with a Calmetrix I-Cal 4000 HPC isothermal conduction calorimeter at 23 °C. Heat flow and cumulative heat release were continuously monitored and normalized to the mass of Portland cement.

2.5 Physical and mechanical characterization

The density of the mortar composites was determined according to ASTM C1329 by calculating the mass-to-volume ratio of the specimens. Prior to testing, the specimens were dried to constant mass under controlled conditions. The density values were obtained from the measured specimen mass and reported as the average of three measurements for each mixture.

The compressive strength of the mortar composites was determined according to ASTM C109. For this purpose, three specimens of each mixture were tested after 3, 7 and 28 days of curing. The specimens were subjected to uniaxial compressive loading until failure using an Instron 600DX hydraulic testing machine. The reported results correspond to the average compressive strength values and their corresponding standard deviations for each mixture.

2.6 Thermophysical characterization and thermal regulation performance

The thermophysical properties of the nanoPCM-mortar composites were evaluated by determining the thermal conductivity, specific heat capacity, thermal diffusivity and thermal effusivity. Thermal conductivity (k) was measured using a TEMPOS thermal properties analyzer (METER Group) equipped with an SH-3 sensor.

Because the mortar specimens contained a low concentration of dispersed nanoPCM in a heterogeneous cementitious matrix, conventional DSC measurements were not considered suitable, as the small specimen masses typically employed are not necessarily representative of the bulk composite (Pomianowski et al., 2014). Therefore, the specific heat capacity (Cp) was determined using a transient calorimetric method previously developed and validated for heterogeneous PCM-containing cementitious materials (Pomianowski et al., 2014), based on heat-flow measurements recorded during specimen cooling proposed for heat conduction calorimetry systems (Lehto et al., 1998). For this purpose, disk-shaped samples with dimensions of 25 mm in diameter and 10 mm in height were dried until reaching constant mass. The samples were heated from 25 °C to 55 °C until thermal equilibrium was achieved, which was monitored using a FLIR TG165 infrared thermometer with an emissivity value of 0.94. Subsequently, the heated specimens were placed inside the calorimeter and the heat flow signal was recorded until thermal equilibrium with the calorimeter was reached. The total thermal energy released during cooling (Ac) was obtained by integrating the heat-flow signal over time and was used to estimate the specific heat capacity according to Equation 1. All measurements were conducted under identical experimental conditions to allow comparative evaluation among mixtures.

Where Ac is the total thermal energy released during cooling (J), T_i is the initial temperature of the sample (°C), T_c is the calorimeter temperature, which was maintained at 23 °C and P_ms is the dry mass of the sample (kg).

The thermal diffusivity (α) and thermal effusivity (ε) were calculated from the density (ρ), thermal conductivity and specific heat capacity values according to Equations 2, 3, respectively (Errebai et al., 2021).

The temperature regulation performance of nanoPCM-mortar composites was evaluated using a homemade insulated chamber, in which the internal temperature evolution of the samples was monitored under controlled heating and cooling conditions. Cubic samples (50 × 50 × 50 mm) were initially conditioned at ambient temperature. The chamber temperature was maintained at 40 °C using a 250 W temperature-controlled infrared lamp positioned 35 cm above the samples. Prior to testing, the temperature inside the chamber was allowed to reach thermal equilibrium. A K-type thermocouple embedded at the center of each specimen was used to continuously monitor the internal temperature. The samples were exposed to the heating stage for 2 h, after which the infrared lamp was switched off, and the samples were allowed to cool naturally until reaching approximately 26 °C. All thermal chamber experiments were performed in triplicate under identical experimental conditions, maintaining the same specimen position relative to the infrared lamp and the same thermocouple location within the specimens. The thermal regulation performance was assessed by comparing the temperature evolution and thermal response of mortars containing different VO₂/MWCNT nanoPCM contents with that of the reference mortar. Similar experimental configurations have been successfully employed to evaluate the thermal regulation behavior of PCM-based cementitious materials (Du et al., 2020; Mohseni et al., 2020).

2.7 Energy efficiency of residential buildings using nanoPCM-mortar composites

Numerical simulations were conducted to investigate the energy efficiency of building envelopes incorporating nanoPCM-mortar composites. The simulations were performed using EnergyPlus 9.1, which is a widely used building energy modeling software. As illustrated in Figure 1, a single-zone residential building with dimensions of 5.4 × 6.0 × 3.0 m was modeled to represent a typical housing unit. The building was assumed to be located on unobstructed flat terrain and free from shading effects caused by neighboring structures. The nanoPCM-mortar composites were incorporated as a 2.5 cm thick exterior rendering layer of the building envelope to investigate their influence on the overall thermal and energy performance of the house.

FIGURE 1

The housing unit was evaluated under three representative climatic conditions in México: Monterrey (hot semi-arid climate, BSh), México City (temperate highland climate, Cwb) and Temósachi (cold semi-arid climate, BSk) according to the Köppen–Geiger climate classification. These locations were selected to represent contrasting climatic conditions commonly found in México. Weather files and hourly climatic data for each location were obtained from the Climate OneBuilding database (Lawrie and Crawley, 2022), which is based on the Integrated Surface Database (ISD) maintained by the U.S. National Oceanic and Atmospheric Administration (NOAA). The building geometry and wall configuration employed in the simulations are presented in Figure 1.

Annual heating, cooling and total energy consumption were calculated, while indoor thermal comfort conditions were assessed using EnergyPlus, following a methodology similar to that reported by Wang et al. (2020). The occupancy schedule considered two occupants with a standard working routine from 9:00 a.m. to 6:00 p.m., Monday through Friday, including weekends, public holidays and vacation periods. An air system was implemented to maintain indoor thermal comfort conditions, using heating and cooling set-point temperatures of 23 °C and 25 °C, respectively, in accordance with the thermal comfort ranges recommended by ASHRAE Standard 55. Heat transfer through the building envelope was modeled using the one-dimensional Conduction Finite-Difference (CondFD) algorithm available in EnergyPlus, which is particularly suitable for transient thermal simulations involving materials with temperature-dependent thermal behavior. The experimentally determined density, thermal conductivity and specific heat capacity of the mortar composites developed in this study were used as input parameters for the exterior rendering layer. All other building characteristics and simulation parameters were kept constant to isolate the effect of nanoPCM incorporation on the thermal and energy performance of the building envelope.

3 Results and discussion

3.1 Characterization of VO₂/MWCNT nanoPCM

Figure 2a presents the XRD diffractograms of the MWCNT, VO₂ nanoparticles and VO₂/MWCNT nanoPCM with a 95:5 mass ratio. The MWCNTs exhibit characteristic diffraction peaks at 25.86 °, 42.54 °, 44.34 ° and 51.66 °, associated with the (002), (100), (101) and (004) planes of the hexagonal graphite structure, in agreement with JCPDS card No. 058–1638. The VO₂ nanoparticles presented sharp and well-defined diffraction peaks at 2θ values of 26.88 °, 27.72 °, 33.35 °, 37.01 °, 39.62 °, 42.23 °, 55.41 °, 57.51 °, 64.91 °, 70.37 ° and 72.06 ° which are indexed to the (110), (011), (11), (200), (020), (201), (220), (022), (031), (312) and (32) crystallographic planes of monoclinic phase (space group P2₁/c), consistent with JCPDS card No. 00–043–1051. The diffraction pattern of the VO₂/MWCNT is dominated by the characteristic reflections of VO₂ due to its high mass proportion in the composite. Notably, no additional diffraction peaks were detected, indicating the absence of secondary phases and that the synthesis process preserved the crystalline structure of both constituents. The exclusive presence of monoclinic VO₂ is particularly important because this polymorph undergoes the reversible thermally induced phase transition responsible for its phase change behavior (Fragoso-Fernández et al., 2022).

FIGURE 2

The morphology of the VO₂/MWCNT is presented in Figure 2b. VO₂ nanoparticles exhibited a nanoflake-like morphology with an average thickness of approximately 5 nm, while the MWCNTs displayed well-defined tubular structures with an average diameter of 30 nm. The nanotubes were distributed throughout the VO₂ nanoflake network and established multiple contact points between adjacent nanoflakes. The interconnected morphology is expected to facilitate heat transport within the nanoPCM and contribute to a more efficient heat distribution throughout the nanocomposite during heating and cooling.

Figure 3 presents the DSC curves of the VO₂ nanoparticles, MWCNTs and VO₂/MWCNT, while the corresponding thermal properties during heating and cooling are summarized in Table 2. As expected, the MWCNTs did not exhibit any thermal transitions, as evidenced by the absence of endothermic and exothermic signals throughout the evaluated temperature range. In contrast, the VO₂ nanoparticles exhibited distinct endothermic and exothermic peaks corresponding to the first-order solid–solid phase change transition between the monoclinic to the rutile phase. The endothermic transition occurred at a transition temperature (Tc) of 72.41 °C during heating, whereas the reverse transition during cooling was observed at 64.15 °C. The latent heats associated with the heating and cooling processes were 40.51 Jg⁻¹ and 32.84 Jg⁻¹, respectively.

FIGURE 3

For the VO₂/MWCNT nanoPCM, a notable shift in phase transition behavior was observed. The endothermic peak appeared at 63.73 °C, representing a reduction of 8.68 °C compared with pure VO₂, while the exothermic peak occurred at 54.53 °C, corresponding to a reduction of 9.62 °C during cooling. This decrease in Tc is advantageous because broadens the potential applicability of the nanoPCM under service conditions where higher surface temperatures can be reached, such as sun-exposed exterior building envelopes. The latent heat of the nanoPCM decreased slightly from 40.51 to 38.06 Jg⁻¹ during heating and from 32.84 to 29.76 Jg⁻¹ during cooling. Such reductions are expected because the incorporation of non-phase change active MWCNTs decreases the fraction of thermally active VO₂ within the nanocomposite. Nevertheless, the nanoPCM retained more than 90% of the latent heat storage capacity of pure VO₂ while exhibiting improved thermal transport properties.

Moreover, thermal conductivity measurements performed on partially compressed powder pellets revealed that the incorporation of MWCNTs increased the thermal conductivity from 0.049 to 0.17 W/m⋅K, corresponding to an enhancement of approximately 3.5 times. The enhanced thermal conductivity and reduced Tc can be attributed to the high intrinsic thermal conductivity of MWCNTs and their ability to establish conductive pathways throughout the PCM matrix, as evidenced by the interconnected morphology observed in the micrograph.

3.2 Physical and mechanical performance of nanoPCM-mortar composites

The density and compressive strength of the nanoPCM-mortar composites are presented in Figure 4. All mortars exhibited densities within the typical range reported for conventional cement mortars (Aodkeng et al., 2022). The incorporation of VO₂/MWCNT resulted in a slight but progressive increase in density, from 2,128 kg/m³ for the reference mortar to 2,186 kg/m³ for the mortar containing 3 wt% nanoPCM, corresponding to an increase of approximately 2.7%. The nanoscale dimension of the VO₂/MWCNT particles may promote a filler effect by occupying the pores within the cementitious matrix, contributing to a denser microstructure.

FIGURE 4

The effect of nanoPCM incorporation on compressive strength was dependent on both dosage and curing age. At 3 days, mortar composites containing 0.5 and 1 wt% nanoPCM exhibited compressive strengths of 11.63 and 12.81 MPa, respectively, compared with 10.48 MPa for the reference. However, further increases in nanoPCM content resulted in lower early-age strength, with values of 8.57 and 6.20 MPa for PCM-mortar composites containing 2 and 3 wt% of VO₂/MWCNT, respectively. Similar trends were observed after 7 days of curing, although the differences between mixtures became less pronounced. At 28 days, all nanoPCM-mortar composites surpassed the reference mortar, indicating that the incorporation of the nanoPCM did not compromise long-term mechanical performance. The highest compressive strength was obtained for the mortar containing 1 wt% nanoPCM reaching 25.15 MPa, which corresponds to an increase of 24.5% compared with the reference. Mortars containing 2 and 3 wt% VO₂/MWCNT also exhibited enhanced strengths with increases of 18.37% and 13.02%, respectively. These results indicate that increasing nanoPCM contents primarily affected early-age strength development, whereas the long-term mechanical performance was preserved or even improved.

The improvement in the compressive strength at low nanoPCM contents is consistent with the increase in density and can be associated with improved particle packing and matrix densification (Wang et al., 2025). The VO₂/MWCNT nanoparticles may act as nano and microfillers, promoting a more compact cementitious matrix. Nevertheless, increasing the nanoPCM content beyond 1 wt% reduced the beneficial effect on compressive strength, although all nanoPCM-mortar composites still outperformed the reference mortar after 28 days. This behavior may be associated with the increasing difficulty of achieving homogeneous nanoparticle dispersion as the nanoPCM content increases. A recent review has highlighted that nanomaterials tend to agglomerate and re-agglomerate within cementitious systems, generating localized heterogeneities that can partially offset the beneficial effects associated with nanofiller incorporation and matrix densification (Mohammadi Ghahsareh et al., 2026). These results suggest that, although the incorporation of up to 3 wt% nanoPCM improved the long-term mechanical performance (28 days), the maximum mechanical response was achieved at 1 wt%, where the beneficial effects of particle packing and matrix densification prevailed over the adverse effects associated with nanoparticle agglomeration.

3.3 Hydration kinetics of VO₂/MWCNT-modified cement pastes

Figure 5 presents the effect of VO₂/MWCNT nanoPCM incorporation on the hydration of cement. The incorporation of nanoPCM progressively modified the hydration process, as evidenced by the heat flow curves through the displacement of the main hydration peak toward longer hydration times and the reduction in the early-age heat evolution rate. This effect became more pronounced as the nanoPCM content increased, particularly for the nanoPCM-mortar composites containing 2 and 3 wt% of VO₂/MWCNT. Nevertheless, the cumulative heat release curves revealed that hydration was not suppressed, since all mixtures eventually reached cumulative heat values comparable to or even higher than that of the reference after 14 days. The cumulative heat release was 6%, 5%, 9.4% and 12.5% higher than the reference for the mortars containing 0.5, 1, 2 and 3 wt% of VO₂/MWCNT, respectively.

FIGURE 5

The delayed hydration may be attributed, at least in part, to the presence of nanomaterials, which can modify the physicochemical environment of the cement hydration system, through surface adsorption, changes in ion transport and water distribution within the pore solution, thereby altering the nucleation and growth kinetics of hydration products (Land and Stephan, 2015; Tafesse and Kim, 2019). In addition, the thermal energy storage capability of the VO₂/MWCNT nanoPCM may also contribute to the observed delay. Previous studies have shown that PCMs can effectively regulate hydration heat, while hydration temperatures exceeding 70 °C have been reported during the early stages of cement hydration (Kim et al., 2015; Ju et al., 2024). Since the VO₂/MWCNT nanoPCM exhibited a Tc of 63.73 °C during heating, activation of the VO₂ solid-solid phase transition during hydration is physically possible. Under these conditions, part of the heat released by the exothermic hydration reactions may be temporarily absorbed through solid-solid phase transition of VO₂ before being gradually released as hydration progresses. The presence of MWCNT may further enhance this behavior by facilitating heat transfer toward the thermally active VO₂ domains, promoting a more efficient utilization of the nanoPCM. Similar synergistic role of carbon nanomaterials has recently been reported for PCM-modified cementitious systems (Ju et al., 2024). Accordingly, the progressively larger displacement of the main hydration peak with increasing VO₂/MWCNT content suggests that higher nanoPCM additions provide greater thermal energy storage capacity during the early stages of hydration. The subsequent convergence of the cumulative heat release curves after approximately 150–200 h indicates that hydration was delayed rather than suppressed. By the end of the monitoring period, the cumulative heat released by the nanoPCM-containing mixtures was comparable to or higher than that of the reference paste, indicating that hydration continued to progress despite the delayed early-age kinetics. A comparable hydration evolution has also been reported for PCM-modified cementitious systems, where delayed hydration was accompanied by higher cumulative heat release at later ages (Kim et al., 2015; Park and Choi, 2021; Aodkeng et al., 2022).

The hydration behavior is fully consistent with the compressive strength evolution of the nanoPCM-mortar composites. The delayed hydration kinetics primarily influenced early-age mechanical behavior, as mortars containing 2 and 3 wt% VO₂/MWCNT exhibited lower compressive strengths at 3 and 7 days. However, as hydration progressed, all samples surpassed the reference after 28 days of curing. These observations indicate that the delayed hydration primarily affects early-age strength development, whereas the beneficial effects associated with nanoPCM incorporation become dominant at later curing ages.

3.4 Microstructure of nanoPCM-mortar composites

The XRD diffractograms of the hydrated pastes after 28 days of curing are shown in Figure 6. All samples exhibited similar diffraction patterns dominated by the characteristic peaks of ettringite (PDF 00–041–1451), portlandite (PDF 00–044–1481) and calcite (PDF 00–005–0586), which are commonly observed hydration products in Portland cement systems.

FIGURE 6

No significant differences were observed in either the type or relative intensity of the crystalline hydration products as the nanoPCM content increased. Likewise, diffraction peaks associated with VO₂ or MWCNT were not detected. This can be attributed to the low nanoPCM content incorporated into the cement matrix (0.5–3 wt%) and the predominance of the cement hydration products, whose diffraction signals largely overshadow those of the nanoPCM. These results indicate that no significant differences in the crystalline hydration products were detected after 28 days of curing with the incorporation of VO₂/MWCNT. Combined with the calorimetry results, which revealed a delay in early hydration kinetics, these findings suggest that the nanoPCM primarily influences the rate of hydration at early ages, while the assemblage of crystalline hydration products at 28 days remains largely unchanged.

Figure 7 presents the microstructural characterization of the nanoPCM-mortar composites. High-resolution SEM images revealed the presence of VO₂ nanoflakes interconnected by MWCNT bundles within the hydrated cement matrix. The characteristic morphology of both components remained identifiable after curing, indicating that the nanoPCM preserved its structural integrity during cement hydration. The micrographs also show that the VO₂/MWCNT agglomerates were embedded within the hydrated matrix and occupied available spaces between hydration products. Furthermore, the MWCNT bundles appeared to form bridges between adjacent VO₂ nanoflakes, generating an interconnected microstructure similar to that observed before incorporation into the cementitious system. In some regions, MWCNTs appeared to extend across the void spaces between hydration products, potentially facilitating thermal transport between adjacent nanoPCM domains.

FIGURE 7

The elemental mapping of vanadium further confirmed the successful incorporation and distribution of the VO₂/MWCNT. The vanadium signal was detected throughout the analyzed area. Although VO₂-related diffraction peaks were not detected by XRD diffractograms, the mapping results demonstrate that the nanoPCM remained present within the matrix after curing. In addition, the presence of VO₂/MWCNT within the microstructure is consistent with the slight increase in density and the compressive-strength improvements observed at moderate nanoPCM contents, while providing the nanoPCM domains responsible for the modified thermophysical behavior of the mortar composites.

3.5 Thermophysical properties and thermal regulation performance

The thermal conductivity was measured at six different mean temperatures, and the results are presented in Figure 8. In general, the incorporation of the VO₂/MWCNT nanoPCM progressively reduced the thermal conductivity of the mortar composites compared with the reference sample. At 25 °C, the reference mortar exhibited a thermal conductivity of approximately 1.51 W/m⋅K, whereas the incorporation of 3 wt% nanoPCM decreased this value to 1.21 W/m⋅K, corresponding to a reduction of 19.86%. Although the incorporation of MWCNTs increased the thermal conductivity of the VO₂ from 0.049 to 0.17 W/m⋅K, the resulting VO₂/MWCNT remained substantially less conductive than the reference mortar. Consequently, the overall thermal conductivity of the mortar composites decreased despite the conductive role of the MWCNTs within the nanoPCM, indicating that the effective thermal conductivity of the nanoPCM-mortar composite is governed by the combined influence of the cementitious matrix and its microstructural characteristics rather than solely by the intrinsic conductivity of the VO₂/MWCNT. A comparable trend has been reported for n-octadecane PCM modified with activated carbon, graphene nanoplatelets, graphene or carbon nanotubes, where carbon nanomaterials enhanced heat transfer within the PCM phase while the overall cementitious composite retained a lower thermal conductivity than the reference material (Kim et al., 2024).

FIGURE 8

Moreover, the reduction in thermal conductivity for the present mortar composites did not follow a linear trend with increasing nanoPCM content, suggesting that heat transport was also influenced by the distribution of the nanoPCM and its interaction with the cementitious matrix. Finally, all nanoPCM-mortar composites presented a slight increase in thermal conductivity with rising temperature but maintained lower thermal conductivity values than the reference sample throughout the evaluated temperature range.

Table 3 summarizes the measured specific heat capacity together with the calculated thermal diffusivity and effusivity of the nanoPCM-mortar composites at 25 °C. The Cp of samples represents the amount of sensible heat required to increase the temperature of the material by one degree. As shown in Table 3, the incorporation of the VO₂/MWCNT produced only a slight reduction in Cp from 862 J/kg⋅K for the reference mortar to 839 J/kg⋅K for the mortar containing 3 wt% VO₂/MWCNT, corresponding to a reduction of ≈2.7%. The measured specific heat capacity values are consistent with those reported for Portland cement mortars in the literature (Shafigh et al., 2020). This relatively small variation indicates that the improved thermal response of the nanoPCM-mortar composites cannot be explained by changes in Cp alone but should be interpreted together with the simultaneous reductions in thermal conductivity, thermal diffusivity, and thermal effusivity, which collectively govern transient heat transfer through the material.

Another important parameter for describing the thermal behavior of construction materials is thermal diffusivity, which represents the rate at which heat propagates through the material. Cement-based materials with lower thermal diffusivity exhibit a slower transient heat transfer response and are generally associated with greater thermal inertia, making them less susceptible to rapid temperature fluctuations (Verbeke and Audenaert, 2018). As shown in Table 3, the thermal diffusivity decreases progressively with increasing VO₂/MWCNT content, from 0.83 × 10⁻⁶ m²/s for the reference mortar to 0.66 × 10⁻⁶ m²/s for the mortar containing 3 wt% nanoPCM, corresponding to a reduction of 20.48%. This reduction indicates that the incorporation of VO₂/MWCNT slowed heat propagation through the mortar, thereby delaying the transmission of thermal disturbances across the material.

Moreover, thermal effusivity describes the ability of a material to absorb or release thermal energy through its surface with its surroundings upon contact, determining how rapidly the material responds to changes in surface temperature (Cottrill et al., 2018). Similar to thermal diffusivity, thermal effusivity decreased progressively with increasing VO₂/MWCNT content, reaching a reduction of 10.8% for the mortar containing 3% nanoPCM compared with the reference mortar. Lower thermal effusivity values indicate a slower rate of heat exchange between the material and its surroundings, which may contribute to a more gradual thermal response and improved temperature buffering capacity.

The simultaneous reductions in specific heat capacity, thermal conductivity, diffusivity and effusivity demonstrate that the incorporation of the VO₂/MWCNT modifies the transient heat transfer characteristics of the nanoPCM-mortar composites. The results indicate a slower heat transfer response, resulting in increased effective thermal inertia, enhanced attenuation of temperature fluctuations under transient thermal conditions and improved passive thermal regulation performance. Similar trends have been reported for cementitious materials containing phase change materials, where PCM incorporation led to reductions in thermal transport properties while improving thermal inertia and transient thermal performance (Olivieri et al., 2018; Shi et al., 2020; Gbekou et al., 2022).

The temperature regulation performance of the nanoPCM-mortar composites is presented in Figure 9 and summarized in Table 4. The internal temperature of the reference mortar increased progressively during heating until reaching approximately 40 °C. In contrast, all nanoPCM-mortar composites exhibited a lower temperature rise throughout the heating stage. This effect became progressively more pronounced with increasing VO₂/MWCNT content.

FIGURE 9

When the reference mortar reached 40 °C after approximately 1.5 h of heating, the mortars containing VO₂/MWCNT exhibited temperatures ranging from 39.8 °C for the mortar with 0.5 wt%–38.9 °C for the mortar with 3 wt%. These values correspond to temperature reductions between 0.2 °C and 1.1 °C relative to the reference mortar. Although the mortar containing 0.5 wt% VO₂/MWCNT exhibited only a slight reduction in peak temperature, progressively larger temperature reductions and thermal delays were observed as the nanoPCM content increased. As shown in Table 4, the time lag increased from 1 min for the mortar containing 0.5 wt% VO₂/MWCNT to 21 min for the mortar containing 3 wt% VO₂/MWCNT. The enhancement in thermal regulation became evident at nanoPCM contents of 2 wt% and above, where the reduction in peak temperatures and the delay in heat propagation were more pronounced. The combination of lower internal temperatures and delayed temperature peaks demonstrate that the incorporation of VO₂/MWCNT effectively modified the transient thermal response of the mortar composites during heating. Considering that the maximum temperature reached during the test remained below the Tc of VO₂, this behavior cannot be attributed to latent heat storage. Instead, it is consistent with the reduced thermal conductivity, diffusivity and effusivity of the nanoPCM-mortar composites, which slowed heat transfer through the cementitious matrix and increased its effective thermal inertia.

During the cooling stage, all mixtures exhibited similar temperature profiles and reached thermal equilibrium within a comparable period. The nanoPCM-mortar composites attained 26 °C slightly earlier than the reference mortar, which can be attributed to the lower peak temperatures reached during the heating period. Therefore, the main benefit of incorporation VO₂/MWCNT under the evaluated conditions was observed during the heating stage, where slower heat propagation delayed the temperature rise and reduced the maximum temperature reached by the PCM-mortar composites.

These results demonstrated that incorporation VO₂/MWCNT improves the transient thermal behavior of cementitious mortars by reducing heat transfer rates and enhancing their thermal buffering capacity. Although the phase transition temperature of the VO₂ was not reached under the present experimental conditions, the modified thermophysical properties of the nanoPCM-mortar composites were sufficient to attenuate temperature fluctuations during heating. These observations are consistent with previous studies reporting that improvements in the thermophysical properties and thermal inertia of PCM-modified cementitious materials contribute to enhanced thermal performance of building envelopes (Yang et al., 2022; Tripathi and Shukla, 2024; Vedrtnam et al., 2025).

3.6 Energy efficiency simulation results

Table 5 summarizes the annual heating, cooling and total energy demands obtained from the EnergyPlus simulations for the three climatic conditions considered. In all cases, the incorporation of VO₂/MWCNT nanoPCM reduced the annual building energy consumption compared with the reference mortar. Furthermore, the energy-saving effect increased progressively with nanoPCM content, with the mortar containing 3 wt% nanoPCM exhibiting the best overall performance under all climatic conditions.

The highest reduction in annual energy consumption was achieved in México City, where the incorporation of 3 wt% nanoPCM decreased the total energy demand from 189.7 to 185.5 kWh/m²·year, corresponding to a saving of 2.23%. Lower but still measurable reductions were observed in Temósachi and Monterrey, where maximum savings of 1.35% and 0.95%, respectively, were obtained.

To better visualize the influence of nanoPCM dosage, the annual energy savings relative to the reference mortar are presented in Figure 10. The improved energy performance can be attributed to the thermophysical modifications induced by the incorporation of the VO₂/MWCNT into the mortar. Experimental measurements showed that nanoPCM addition reduced the thermal conductivity, diffusivity and effusivity of the nanoPCM-mortar composites, while only slightly affecting their specific heat capacity. Collectively, these changes slowed transient heat transfer through the building envelope and consequently reduced the energy required to maintain thermal comfort conditions.

FIGURE 10

These results highlight the potential of VO₂/MWCNT nanoPCM-mortar composites as a practical strategy for improving the thermal performance of building envelopes without requiring high PCM loadings or major modifications to conventional construction systems. Similar trends have been reported in previous studies. L. Zhuo et al. investigated cementitious materials incorporating a solid–gel phase change material and observed that increasing the PCM content from 10 to 30 vol% reduced annual cooling-energy consumption by 0.89%–4.43%, while the corresponding reduction in heating demand remained below 0.4% (Liu et al., 2023). Likewise, F. Lygerakis et al. reported net annual energy savings of 2.6% in a Mediterranean climate using cement boards containing 10 wt% of a shape-stabilized n-octadecane PCM, a conventional solid–liquid PCM system. Increasing the PCM content to 30 wt% was required to achieve a maximum saving of 4.8% (Lygerakis et al., 2025). In comparison, the present study achieved annual energy savings of up to 2.23% using only 3 wt% of VO₂/MWCNT incorporated into a 2.5 cm thick exterior mortar coating. Although the absolute savings were moderate, they were achieved with substantially lower nanoPCM content than those commonly reported for cementitious PCM systems. These results indicate that improving the thermophysical properties and transient heat transfer characteristics of cementitious materials can contribute to measurable reductions in building energy demand without requiring high PCM loading or major modifications to conventional construction systems. Therefore, optimizing the thermophysical properties of cementitious composites, together with facilitating heat transport within the nanoPCM through conductive nanostructures such as MWCNTs, represents an effective strategy for enhancing the thermal performance of building envelopes while minimizing nanoPCM incorporation.

4 Conclusion

References

• 1

  AodkengS.SinthupinyoS.ChamnankidB.HanpongpunW.ChaipanichA. (2022). Effect of carbon nanotubes/clay hybrid composite on mechanical properties, hydration heat and thermal analysis of cement-based materials. Constr. Build. Mater.320, 126212. 10.1016/j.conbuildmat.2021.126212

  • CrossRef
  • Google Scholar
  • View reference in article

• 2

  BabaM.NemotoK.OtakiD.SasakiT.TakedaM.YamadaN. (2021). Temperature leveling of electronic chips by solid-solid phase change materials compared to solid-liquid phase change materials. Int. J. Heat. Mass Transf.179, 121731. 10.1016/j.ijheatmasstransfer.2021.121731

  • CrossRef
  • Google Scholar
  • View reference in article

• 3

  CottrillA. L.LiuA. T.KunaiY.KomanV. B.KaplanA.MahajanS. G.et al (2018). Ultra-high thermal effusivity materials for resonant ambient thermal energy harvesting. Nat. Commun.9, 664. 10.1038/s41467-018-03029-x

  • Pubmed Abstract
  • CrossRef
  • Google Scholar
  • View reference in article

• 4

  DuY.LiuP.QuanX.MaC. (2020). Characterization and cooling effect of a novel cement-based composite phase change material. Sol. Energy208, 573–582. 10.1016/j.solener.2020.07.083

  • CrossRef
  • Google Scholar
  • View reference in article

• 5

  ErrebaiF. B.ChikhS.DerradjiL.AmaraM.YounsiZ. (2021). Optimum mass percentage of microencapsulated PCM mixed with gypsum for improved latent heat storage. J. Energy Storage33, 101910. 10.1016/j.est.2020.101910

  • CrossRef
  • Google Scholar
  • View reference in article

• 6

  Figueroa-TorresM. Z.González-LópezJ. R.Guerra-CossioM. A.González-JuárezE.Alonso-LemusI. L.Fragoso-FernándezC. Y. (2025). Novel VO2/MWCNT nanophase change material composite incorporated into gypsum for indoor thermoregulation in buildings. Constr. Build. Mater.492, 142825. 10.1016/j.conbuildmat.2025.142825

  • CrossRef
  • Google Scholar
  • View reference in article

• 7

  Fragoso-FernándezC. Y.González-LópezJ. R.Guerra-CossíoM. A.Toxqui-TeránA.Zaldívar-CadenaA. A.Figueroa-TorresM. Z. (2022). Study on thermally stabilized vanadium dioxide nanoparticles solid–solid phase change thermal energy storage material. J. Mater. Sci. Mater. Electron.33, 26580–26589. 10.1007/s10854-022-09334-y

  • CrossRef
  • Google Scholar
  • View reference in article

• 8

  GbekouF. K.BenzartiK.BoudenneA.EddhahakA.DucM. (2022). Mechanical and thermophysical properties of cement mortars including bio-based microencapsulated phase change materials. Constr. Build. Mater.352, 129056. 10.1016/j.conbuildmat.2022.129056

  • CrossRef
  • Google Scholar
  • View reference in article

• 9

  GhamariM.SeeC. H.HughesD.MallickT.ReddyK. S.PatchigollaK.et al (2024). Advancing sustainable building through passive cooling with phase change materials, a comprehensive literature review. Energy Build.312, 114164. 10.1016/j.enbuild.2024.114164

  • CrossRef
  • Google Scholar
  • View reference in article

• 10

  HuY.WangH.DuanY.ChenK.LiJ.LinL.et al (2026). Thermal energy “shifting” and spatial regulation: a review of the design and application of thermal storage composite cementitious material. Renew. Sustain. Energy Rev.238, 117064. 10.1016/j.rser.2026.117064

  • CrossRef
  • Google Scholar
  • View reference in article

• 11

  JinW.JiangL.ChenL.GuY.GuoM.HanL.et al (2021). Preparation and characterization of capric-stearic acid/montmorillonite/graphene composite phase change material for thermal energy storage in buildings. Constr. Build. Mater.301, 124102. 10.1016/j.conbuildmat.2021.124102

  • CrossRef
  • Google Scholar
  • View reference in article

• 12

  JuS.LuoQ.LuZ.WangF.ShiJ.WangL.et al (2024). A novel thermal-tailored strategy to mitigate thermal cracking of cement-based materials by carbon fibers and liquid-metal-based microencapsulated phase change materials. Constr. Build. Mater.428, 136338. 10.1016/j.conbuildmat.2024.136338

  • CrossRef
  • Google Scholar
  • View reference in article

• 13

  KimY.-R.KhilB.-S.JangS.-J.ChoiW.-C.YunH.-D. (2015). Effect of barium-based phase change material (PCM) to control the heat of hydration on the mechanical properties of mass concrete. Thermochim. Acta613, 100–107. 10.1016/j.tca.2015.05.025

  • CrossRef
  • Google Scholar
  • View reference in article

• 14

  KimY. U.YangS.KimS. (2024). Thermal characteristics of cementitious building materials with carbon and PCM for improved heat storage performance. Constr. Build. Mater.449, 138550. 10.1016/j.conbuildmat.2024.138550

  • CrossRef
  • Google Scholar
  • View reference in article

• 15

  LandG.StephanD. (2015). Controlling cement hydration with nanoparticles. Cem. Concr. Compos.57, 64–67. 10.1016/j.cemconcomp.2014.12.003

  • CrossRef
  • Google Scholar
  • View reference in article

• 16

  LawrieL. K.CrawleyD. B. (2022). Development of Global Typical Meteorological Year (TMYx) and Typical Design Day Data for Building Energy Simulation. Available online at: https://climate.onebuilding.org (Accessed May 17, 2026).

  • Google Scholar
  • View reference in article

• 17

  LehtoV.-P.RahkolaM.LaineE.YlianttilaL.HyssaloP.JokelaK. (1998). Determination of specific heats using isothermal microcalorimetry. J. Therm. Anal. Calorim.53, 685–695. 10.1023/A:1010166005911

  • CrossRef
  • Google Scholar
  • View reference in article

• 18

  LiuZ.DuJ.SteereR.SchlegelJ. P.KhayatK. H.WeinaM. (2023). Cement-based materials with solid–gel phase change materials for improving energy efficiency of building envelope. J. Mater. Civ. Eng.35, 4023425. 10.1061/JMCEE7.MTENG-15925

  • CrossRef
  • Google Scholar
  • View reference in article

• 19

  LygerakisF.GiotiC.KarakassidesM. A.GournisD. P.YentekakisI. V.KolokotsaD. (2025). Impact of accelerated weather aging on building energy efficiency using cement and gypsum boards with shape-stabilized phase change materials. Sci. Rep.15, 40884. 10.1038/s41598-025-24728-8

  • CrossRef
  • Google Scholar
  • View reference in article

• 20

  Mohammadi GhahsarehF.GuoP.JahaN.BaoY.KhayatK. H.MengW. (2026). Advances and challenges in nano-modified cementitious composites: mechanisms, dispersion strategies, and impact on mechanical properties. J. Build. Eng.119, 115138. 10.1016/j.jobe.2025.115138

  • CrossRef
  • Google Scholar
  • View reference in article

• 21

  MohseniE.TangW.KhayatK. H.CuiH. (2020). Thermal performance and corrosion resistance of structural-functional concrete made with inorganic PCM. Constr. Build. Mater.249, 118768. 10.1016/j.conbuildmat.2020.118768

  • CrossRef
  • Google Scholar
  • View reference in article

• 22

  OlivieriL.TenorioJ. A.RevueltaD.NavarroL.CabezaL. F. (2018). Developing a PCM-enhanced mortar for thermally active precast walls. Constr. Build. Mater.181, 638–649. 10.1016/j.conbuildmat.2018.06.013

  • CrossRef
  • Google Scholar
  • View reference in article

• 23

  ParkB.ChoiY. C. (2021). Investigating the effect of CNTs on early age hydration and autogenous shrinkage of cement composite. Appl. Sci.11, 5545. 10.3390/app11125545

  • CrossRef
  • Google Scholar
  • View reference in article

• 24

  PomianowskiM.HeiselbergP.JensenR. L.ChengR.ZhangY. (2014). A new experimental method to determine specific heat capacity of inhomogeneous concrete material with incorporated microencapsulated-PCM. Cem. Concr. Res.55, 22–34. 10.1016/j.cemconres.2013.09.012

  • CrossRef
  • Google Scholar
  • View reference in article

• 25

  ShafighP.AsadiI.AkhianiA. R.MahyuddinN. B.HashemiM. (2020). Thermal properties of cement mortar with different mix proportions. Mater. Constr.70, 1–12. 10.3989/mc.2020.09219

  • CrossRef
  • Google Scholar
  • View reference in article

• 26

  ShiJ.TanJ.LiuB.LiuY.XuH.WangZ.et al (2020). Thermal and mechanical properties of thermal energy storage lightweight aggregate mortar incorporated with phase change material. J. Energy Storage32, 101719. 10.1016/j.est.2020.101719

  • CrossRef
  • Google Scholar
  • View reference in article

• 27

  SuW.DarkwaJ.KokogiannakisG. (2015). Review of solid–liquid phase change materials and their encapsulation technologies. Renew. Sustain. Energy Rev.48, 373–391. 10.1016/j.rser.2015.04.044

  • CrossRef
  • Google Scholar
  • View reference in article

• 28

  TafesseM.KimH.-K. (2019). The role of carbon nanotube on hydration kinetics and shrinkage of cement composite. Compos. Part B Eng.169, 55–64. 10.1016/j.compositesb.2019.04.004

  • CrossRef
  • Google Scholar
  • View reference in article

• 29

  TogunH.BasemA.JweegM. J.MohammedH. I.AbedA. M.AnqiA. E.et al (2025). A review of phase-change materials for building applications: innovations, assessments, and design Implications. Energy Build.349, 116573. 10.1016/j.enbuild.2025.116573

  • CrossRef
  • Google Scholar
  • View reference in article

• 30

  TripathiB. M.ShuklaS. K. (2024). A comprehensive review of the thermal performance in energy efficient building envelope incorporated with phase change materials. J. Energy Storage79, 110128. 10.1016/j.est.2023.110128

  • CrossRef
  • Google Scholar
  • View reference in article

• 31

  VedrtnamA.KalauniK.SoaresN.SalazarB.OstertagC. P.TaylorH. K. (2025). Phase change materials for climate-adaptive buildings: a review framed by tropical and mediterranean climates. J. Energy Storage125, 116938. 10.1016/j.est.2025.116938

  • CrossRef
  • Google Scholar
  • View reference in article

• 32

  VerbekeS.AudenaertA. (2018). Thermal inertia in buildings: a review of impacts across climate and building use. Renew. Sustain. Energy Rev.82, 2300–2318. 10.1016/j.rser.2017.08.083

  • CrossRef
  • Google Scholar
  • View reference in article

• 33

  WangH.LuW.WuZ.ZhangG. (2020). Parametric analysis of applying PCM wallboards for energy saving in high-rise lightweight buildings in Shanghai. Renew. Energy145, 52–64. 10.1016/j.renene.2019.05.124

  • CrossRef
  • Google Scholar
  • View reference in article

• 34

  WangX.QuF.ShiL.HuangY.LiZ.LiW. (2025). Enhancing thermal regulation and mechanical properties of phase change mortar using carbon nanomaterials. Constr. Build. Mater.494, 143448. 10.1016/j.conbuildmat.2025.143448

  • CrossRef
  • Google Scholar
  • View reference in article

• 35

  XiongT.ShahK. W.KuaH. W. (2022). Application of graphite platelets for heat transfer enhancement of cementitious composites containing microencapsulated phase change materials. Constr. Build. Mater.318, 126024. 10.1016/j.conbuildmat.2021.126024

  • CrossRef
  • Google Scholar
  • View reference in article

• 36

  YangH.XuZ.CuiH.BaoX.TangW.SangG.et al (2022). Cementitious composites integrated phase change materials for passive buildings: an overview. Constr. Build. Mater.361, 129635. 10.1016/j.conbuildmat.2022.129635

  • CrossRef
  • Google Scholar
  • View reference in article