Thermal Comfort Research Articles

Combining energy generation and radiant systems: Challenges and possibilities for plus energy buildings

Radiant heating and cooling (RHC) systems are being more widely adopted considering the well-known technical advantages: increased thermal comfort, space saving, and reduced energy use. Since the building sector is currently one of the largest consumers of fossil fuels, many directives and regulations have been enacted to address the intense concern about energy use for space conditioning.Even though radiant systems are considered as an energy efficient technology for building heating and cooling, more effort is needed to fulfil the zero energy requirements outlined by recent standards and directives. Renewable Energy Sources (RES) are an effective solution to avoid using finite fossil fuels and related geopolitical issues enhanced by the recent world conflicts. Despite being primarily intermittent and subject to economic and regional constraints, RES offer suitable temperature levels to supply low temperature heating and high temperature cooling operation, a major advantage of RHC system.Although a limited number of studies directly report energy savings or CO2 emission reduction as the main outcomes of the research related to this combination, valuable insights have been obtained for the present review. Primary energy can decrease between 40% and 80% with different integration of RHC, photovoltaic, heat pumps and district heating. TABS can lead to load shifting up to 100%, allowing an increased self −consumption of renewable energy.This paper provides evidence on whether coupling radiant systems with renewables is a promising strategy for achieving nearly-zero annual energy balances in building stocks. It investigates recent trends, limitations and potential to support decarbonization goals.

Calculating the local and overall view factors of a multi-segment human model

In non-uniform environments, such as spaces with radiant ceilings or floors, or with hot or cold windows, view factors (VFs) of a person towards these surfaces are needed for calculating the heat exchanges between the person and the surroundings. Multi-body segmented human models can simulate the heat exchanges of individual body parts with the environment. Simulating heat transfer at the local body parts is important for assessing comfort in non-uniform environments. These models require VFs for each individual body part. Accurately determining these VFs is time-consuming, often requiring methods such as ray-tracing techniques. A fast calculation method to accurately determine the view factor (VF) for each segment has yet to be investigated. This study employed a 16-segment human model into various architectural radiation scenarios. The surface-to-surface model in computational fluid dynamics was utilized to simulate VFs for the 16 body segments in relation to radiant surfaces at different locations. Through a series of simulations, comprehensive formulas for VFs were derived for each individual at various positions within a room, encompassing 16 body segments and computing parameters for 24 building surfaces. The accuracy of these general formulas was validated by comparing the whole-body VF with results from several available studies. Additionally, this study developed a visualization tool for calculating VF and mean radiant temperatures with different room space dimension and embedded radiant surfaces. The users can use this online tool to easily calculate VFs and mean radiant temperatures for each body parts, and for the whole-body. The tool offers valuable insights for predicting thermal comfort in asymmetric radiant environments and facilitating control over building environments.

Asymmetric Aramid Aerogel Composite with Durable and Covert Thermal Management via Janus Heat Transfer Structure.

Warmth preservation in cold climates requires a long-term heat supply. Conventional thermal devices usually deliver excessive heat and have difficulty preventing heat loss. Herein, to achieve durable thermal comfort, an asymmetric composite (AAAC) is devised through vacuum-filtrating silver nanowires (AgNWs) onto the surface of a poly(ethylene glycol) (PEG)-infiltrated aramid nanofiber aerogel. AgNW e-skin can transfer strong Joule heat to the back side of the AAAC, where the infused PEG further stores thermal energy by phase transition and then releases it to the body constantly after the power is off. Base on the Janus structure, the AAAC can provide thermotherapy for human waists and knees, holding a suitable temperature range of 37-39 °C for 5-8 min without a heat source. In addition, low infrared emissivity (0.064-0.315) of e-skin allows the AAAC to conceal thermal targets while producing Joule heat, which achieves comfortable and safe thermal management in multiple occasions including daily life and military warfare.

NSGA-II and fuzzy comprehensive evaluation-based optimal strategy for dynamic energy optimization considering local thermal sensation

NSGA-II and fuzzy comprehensive evaluation-based optimal strategy for dynamic energy optimization considering local thermal sensation

Integrating Machine Learning and Genetic Algorithms to Optimize Building Energy and Thermal Efficiency Under Historical and Future Climate Scenarios

As the global energy demand rises and climate change creates more challenges, optimizing the performance of non-residential buildings becomes essential. Traditional simulation-based optimization methods often fall short due to computational inefficiency and their time-consuming nature, limiting their practical application. This study introduces a new optimization framework that integrates Bayesian optimization, XGBoost algorithms, and multi-objective genetic algorithms (GA) to enhance building performance metrics—total energy (TE), indoor overheating degree (IOD), and predicted percentage dissatisfied (PPD)—for historical (2020), mid-future (2050), and future (2080) scenarios. The framework employs IOD as a key performance indicator (KPI) to optimize building design and operation. While traditional indices such as the predicted mean vote (PMV) and the thermal sensation vote (TSV) are widely used, they often fail to capture individual comfort variations and the dynamic nature of thermal conditions. IOD addresses these gaps by providing a comprehensive and objective measure of thermal discomfort, quantifying both the frequency and severity of overheating events. Alongside IOD, the energy use intensity (EUI) index is used to assess energy consumption per unit area, providing critical insights into energy efficiency. The integration of IOD with EUI and PPD enhances the overall assessment of building performance, creating a more precise and holistic framework. This combination ensures that energy efficiency, thermal comfort, and occupant well-being are optimized in tandem. By addressing a significant gap in existing methodologies, the current approach combines advanced optimization techniques with modern simulation tools such as EnergyPlus, resulting in a more efficient and accurate model to optimize building performance. This framework reduces computational time and enhances practical application. Utilizing SHAP (SHapley Additive Explanations) analysis, this research identified key design factors that influence performance metrics. Specifically, the window-to-wall ratio (WWR) impacts TE by increasing energy consumption through higher heat gain and cooling demand. Outdoor temperature (Tout) has a complex effect on TE depending on seasonal conditions, while indoor temperature (Tin) has a minor impact on TE. For PPD, Tout is a major negative factor, indicating that improved natural ventilation can reduce thermal discomfort, whereas higher Tin and larger open areas exacerbate it. Regarding IOD, both WWR and Tin significantly affect internal heat gains, with larger windows and higher indoor temperatures contributing to increased heat and reduced thermal comfort. Tout also has a positive impact on IOD, with its effect varying over time. This study demonstrates that as climate conditions evolve, the effects of WWR and open areas on TE become more pronounced, highlighting the need for effective management of building envelopes and HVAC systems.

Health-Related Parameterization Evaluating Thermal Comfort in Urban Green Spaces: Data Sourced from a Global Database and Mapping at National Scale

Outdoor thermal comfort (OTC) is one of the most important issues for people exposed to urban green space (UGS). It is mainly evaluated by assessing equivalent meteorological factors that may combine and result in human responses of perceptions about comfortable vs. uncomfortable environments. The assessment of these responses is challenged by limits in a database that is powerful enough to support big-data analysis and an essential parameter that can evaluate health-related responses to OTC in urban forests. In this study, a meta-analysis was conducted by synthesizing studies of physiological and psychological health responses of green space (GS) visitors to meteorological factors in host cities on a global scale. A total of 15,000 numerical records about the psychological and physiological responses of UGS visitors were obtained from 105 papers across 68 global cities in 21 countries. A novel parameterization was developed to evaluate OTC by normalizing changes in health-related parameters and detecting their regressions against multiple meteorological factors. It was revealed that OTC resulted in more benefits in psychological health parameters than in physiological ones for UGS visitors worldwide. Globally, health-promoting OTC environments were more found in temperate countries than in countries subjected to other climates. People in Asian countries were indicated to live in environments with higher comfort that benefitted health states in cities at low latitudes. Thermal environments tended to be harsher and more challenging, mostly too chilling, in northern cities than in the south globally. A deep learning model using the ResNet algorithm was found to perform to an expected level with R2 as high as >70% and errors controlled generally lower than 0.01. Taking mainland China for instance, it was predicted that thermal environments in eastern cities of China highly challenged the psychological health of local UGS visitors across all seasons of the year. Northern cities of China were predicted to have satisfied thermal environments that benefited psychological and psychological health responses in spring. In summer, cities in West China were predicted to have comfortable thermal environments, and in winter, environments in the southwestern cities were more comfortable.

How does temperature affect rural income: Channels and implication of adaptation

AbstractThis paper examines the impact of daily temperature variations on rural income per capita and evaluates the effectiveness of adaptation based on China's county‐level socioeconomic statistics and household survey data. We find that high temperatures have significant negative effects on rural income per capita. Relative to the physically comfortable reference temperature between 10 and 15°C, an additional day with a daily average temperature above 30°C reduces the rural income per capita by 0.12% in the year. Evidence from micro‐data indicates that agricultural income of rural households is sensitive to high temperatures relative to other components of household income, such as wage income and transfer income, which leads to a reallocation of rural laborers across sectors. In addition, we indeed find some evidence of adaptation, but we conclude that the current adaptation pattern of rural households probably magnifies the threat of future climate change to China's agricultural sector.

Traditional and contemporary building thermal sensations prediction models in a warm-humid climate

ABSTRACT Passive ways of providing thermal comfort have been intensively researched in many nations. Despite researchers’ strenuous efforts, most studies on thermal comfort concerns are centred on continents such as Asia, America, Europe, and Africa, with a handful of studies comparing building types in the sub-Saharan area. However, none has focused on statistical models to predict the thermal sensations of occupants in traditional and modern structures during the dry season. Hence, this study investigated interior relative humidity, air temperature, and occupants’ thermal feelings in traditional and modern structures in the dry season in Okigwe, Nigeria. The data for this investigation was collected by physically measuring relative humidity and air temperature using data loggers. A longitudinal survey technique was also used to elicit answers from the residents of the selected traditional and modern structures on the thermal feeling of comfort temperature. To predict the inhabitants’ thermal sensations in the building types investigated, two statistical models were developed: ‘TSVt = 0.65 (MITt) – 13.5’ for traditional structures and ‘TSVc = 0.74 (MITc) – 16’ for modern. The comfort range and neutral temperature of ‘3.15 ≤ TSV ≤ 4.85’ 1–7 yielded 26.8°C as the neutral temperature for the occupants of traditional buildings, with the comfort ranging between 25.6°C and 28.2°C. Contemporary building occupants’ neutral temperature and comfort ranges from 25.9°C to 28.2°C. The study therefore recommended the use of the developed models by Architects, Planners, and Designers for predicting the occupants’ sensations of the building types before preliminary investigations and design sketches, as with such information, the designer possesses the necessary tools for providing buildings that are thermally comfortable for maximum comfort and minimal consumption of energy.

Evaluating the Effect of Adaptive Reuse in the Energy Performance of Historic Buildings: A Case Study from Türkiye

The building sector accounts for 30% to 40% of total energy consumption, and historic buildings play an important role in this proportion. Historical buildings that do not meet the required comfort conditions for the residents are adaptively reused, with various revisions. Recognizing the energy design of a historical building in its original condition and comparing the current situation can help create future solutions. This study examines the changes that a historic house in a hot climate zone in Türkiye experiences, from its original state up until the current situation. Energy analyses of the pre- and post-restoration situation are carried out, and the effect of adaptive reuse decisions on the energy performance of the building is investigated. A dynamic thermal simulation created with DesignBuilder was used to identify the energy use, carbon emissions, and thermal comfort. TM59 adaptive thermal comfort was used for the pre-restoration and the Fanger model for the post-restoration phase. This building, which was repurposed from a three-block residence, consists of a four-block hotel. Although the preservation of its original value is at the forefront, various structural changes were observed. The analysis demonstrates a higher occurrence of discomfort hours during summer compared to winter, consistent across both phases. Furthermore, energy consumption increased significantly, predominantly for heating, representing a doubling of energy use during the post-restoration phase. This is attributed to the building’s conversion into a hotel and the use of mechanical systems. Future research is required to develop strategies to reduce the energy consumption, carbon emissions, and discomfort hours while maintaining the value of the historic building and its materials.

A Review on the Effective Utilization of Organic Phase Change Materials for Energy Efficiency in Buildings

Energy efficiency is critical for achieving building sustainability because it means that fewer resources are consumed. In this context, the advancement of phase-changing materials has attracted attention with regard to the integration and management of energy efficiency in construction projects. Buildings consume 40% of the global energy output annually, accounting for one-third of the global greenhouse gas emissions. For hot weather-prone construction, PCMs should have a melting temperature of 25–50 °C. For more than 30 years, researchers worldwide have experimented with PCMs at various temperatures, but few studies have been conducted in hot or harsh environments. According to recent studies, the amount of PCMs in construction materials has been limited to 20%, and exceeding this ratio was shown to significantly affect the compressive strength of concrete specimens. In this study, various phase-changing concrete materials were investigated to reduce the thermal energy consumption of buildings. This paper aims to provide an overview of the current state-of-the-art phase change materials for constructing thermal energy storage building materials. It also includes a brief review of the most recent developments in phase change technologies and their encapsulation techniques based on thermophysical properties. Implementing PCM technology in buildings will also maintain good indoor air quality. These materials are widely used in various real-time applications to significantly enhance thermal comfort in buildings.

Effect of ethanol addition on enhancing the cooling performance improvement of spray system

The widespread application of spray technology has significantly improved outdoor environmental thermal comfort. However, the spray system is unable to fulfill special comfort requirements. Utilizing mechanical ventilation and control systems effectively enhances the cooling performance of spray systems; however, those approaches are associated with elevated costs and maintenance complexities. The combination of ethanol and water has been demonstrated to produce a lower surface tension and a higher latent heat of evaporation, a property that contributes to the heat transfer efficiency and evaporation rate of the droplets. Considering the convenience and cost-effectiveness of adding ethanol as an additive, it emerges as the optimal choice. To evaluate the effectiveness of ethanol on the evaporative cooling performance of the spray system, a comparative study was conducted, comparing the cooling performances of different concentrations of ethanol with a spray system without ethanol addition. Five operating conditions were designed, including a no-spray case, a non-additive case, a 0.5 % ethanol concentration case, a 1.0 % ethanol concentration case, and a 1.5 % ethanol concentration case. The results demonstrated that adding ethanol effectively enhanced the cooling performance of the spray system. At 1.7m above ground level (0.4m away from the nozzle), compared to the non-additive case without ethanol, the 0.5 % ethanol concentration case, 1.0 % ethanol concentration case, and 1.5 % ethanol concentration case further reduced the temperature by 0.95 °C, 1.64 °C, and 2.27 °C. Moreover, the relative humidity grew by 3.57 %, 9.25 %, and 13.5 %, respectively. Adding ethanol significantly enhanced the evaporative cooling effect of the spray system, with the optimal concentration observed at 1.5 %. The results demonstrate that enhancing the evaporative cooling efficacy of a spray system by introducing ethanol into the spray medium represents a viable strategy and improve urban thermal environment in summer. Furthermore, this study aims to examine the impact of droplet evaporation on relative humidity, establishing a foundation for future enhancements aimed at addressing the issue of over-humidification in spray systems.

Modelling of Indoor Air Quality and Thermal Comfort in Passive Buildings Subjected to External Warm Climate Conditions

Air renewal rate is an important parameter for both indoor air quality and thermal comfort. However, to improve indoor thermal comfort, the air renewal rate to be used, in general, will depend on the outdoor air temperature values. This article presents the modelling of indoor air quality and thermal comfort for occupants of a passive building subject to a climate with warm conditions. The ventilation and shading strategies implemented for the interior spaces are then considered, as well as the use of an underground space for storing cooled air. The indoor air quality is evaluated using the carbon dioxide concentration, and thermal comfort is evaluated using the Predicted Mean Vote index. The geometry of the passive building, with complex topology, is generated using a numerical model. The simulation is performed by Building Thermal Response software, considering the building’s geometry and materials, ventilation, and occupancy, among others. The building studied is a circular auditorium. The auditorium is divided into four semi-circular auditoriums and a central circular space, with vertical glazed windows and horizontal shading devices on its entire outer surface. Typical summer conditions existing in a Mediterranean-type environment were considered. In this work, two cases were simulated: in Case 1, the occupation is verified in the central space and the four semi-circular auditoriums and all spaces are considered as one; in Case 2, the occupation is verified only in each semi-circular auditorium and each one works independently. For both cases, three strategies were applied: A, without shading and geothermal devices; B, with a geothermal device and without a shading device; and C, with both shading and geothermal devices. The airflow rate contributes to improving indoor air quality throughout the day and thermal comfort for occupants, especially in the morning. The geothermal and shading devices improve the thermal comfort level, mainly in the afternoon.

The Impact of Different Types of Trees on Annual Thermal Comfort in Hot Summer and Cold Winter Areas

Trees positively improve the annual thermal comfort of the built environment in tropical areas, where climate change is slight throughout the year. However, for areas with high changes in climate all year, the current studies have only explored the summer cooling performance of trees without the impact of different types of trees on annual thermal comfort, especially in cold seasons. Therefore, to quantify the impacts and scientifically guide the optimization of green space layout in hot summer and cold winter areas, this study selected Changsha City as the study area and analyzed how the annual thermal comfort is affected by evergreen trees and deciduous trees, which are two common types of trees in hot summer and cold winter areas. The analytical results indicated that the difference in the effect of deciduous and evergreen trees on outdoor thermal comfort was insignificant in summer, where the difference in the monthly mean PET for the three summer months was slight, being 0.28 °C, 0.14 °C, and 0.29 °C, respectively. However, evergreen trees greatly exacerbated winter cold compared to deciduous trees, with a monthly mean PET decrease by nearly 1.0 °C and an hourly PET reduced by up to 3.57 °C. The difference is mainly attributed to the absorption and reflection of solar radiation by the tree canopy, as well as the cooling and humidifying effect of the tree leaf. In hot summer and cold winter areas, outdoor thermal comfort is still in the “comfortable” and “slightly warm” acceptable stage despite the warming effect of deciduous trees in the spring and autumn seasons. Planting evergreen trees is an inevitable thermal mitigation choice for tropical areas. However, for the areas with high annual climate change, such as hot summer and cold winter areas in China, a change in empirical tree planting patterns and selecting deciduous trees where appropriate will improve year-round outdoor thermal comfort.

Heat stress, thermal comfort and control strategy in a warm-humid workplace.

The purpose of this study was to design a local ventilation system (LVS) to help reduce the moisture content of a Scalder hall, evaluate its comfort and thermal stress before and after implementation of LVS and introduce an appropriate index to evaluate warm and humid workplaces. The design of the LVS was performed according to the ACGIH standard (VS-30-01). Heat stress and thermal comfort assessment were performed before and after LVS using humidity index (Humidex), discomfort index (DI), heat index (HI), wet-bulb globe temperature (WBGT) and predicted mean vote index (PMV) indices and the results were compared with predicted mean vote index-predicted percentage of dissatisfied (PMV-PPD) subjective indices. The results of heat stress parameters showed that LVS was able to reduce relative humidity (RH) and wet temperature (tnw) by 47% and 7 ° C, respectively. This has caused subjects to feel the heat from hot and very RH hot to warm and the hot and percentage of dissatisfaction has dropped by more than 70%. Design and implementation of a LVS reduced the ambient tnw by decreasing RH. Results also showed in warm and humid workplaces, DI index are highly correlated with subjective evaluation of thermal comfort and this index can be used to evaluate the thermal conditions of the workplaces.

Optimization of coupling phase-change materials and thermal screens in façade-integrated hybrid photovoltaic collectors for optimal energy production and thermal comfort in buildings

The operation of building-integrated photovoltaic (BIPV) systems gives rise to a significant proportion of the solar radiation absorbed by the cells being unable to be converted into electricity. This phenomenon consequently increases the temperature. This temperature increase impacts the cells' electrical efficiency, leading to a reduction in their performance and accelerating their degradation. The combination of phase-change materials with insulating fluid blades, situated behind photovoltaic cells, represents a passive cooling solution that optimizes the performance of hybrid photovoltaic systems when incorporated into facades. The present study assesses a system that incorporates paraffin as a PCM and an argon layer in a PV-PCM-argon layer physical model (PVT/ArPCM), in comparison with a PV-PCM system (PVT/PCM), to enhance the thermoelectric performance of photovoltaic systems mounted on façades while ensuring optimal thermal comfort within buildings. The discrete heat transfer equations were solved using the Thomas algorithm and the iterative Gauss-Seidel method in conjunction with the implicit finite difference method. The findings illustrate that the electrical efficiency experienced only a slight increase, estimated at 0.01%, while there was a notable enhancement in the indoor thermal comfort experienced by occupants, with a 65% improvement observed due to the incorporation of an argon-filled thermal screen. The incorporation of an argon layer led to a minor reduction in temperature of 0.01°C in the photovoltaic cells, resulting in a minimal improvement of 0.014% in electrical power production. The phase-changing material incorporated into PVT/ArPCM demonstrated superior thermal management capabilities in comparison to the same material employed in PVT/PCM.

The Regulation of Temperature Fluctuations and Energy Consumption in Buildings Using Phase Change Material–Gypsum Boards in Summer

This study examined the thermal performance of Comfortboard23, a commercial gypsum board from Knauf infused with phase change material (PCM). Structural characterization using XRD and SEM confirmed the presence of microencapsulated PCM within the gypsum matrix. The study does not provide a direct comparison between Comfortboard23 and other PCM-integrated gypsum boards on the market. This is a limitation of the research. A comprehensive comparison would involve testing multiple products under identical conditions, and evaluating factors such as thermal performance, cost-effectiveness, durability, and ease of installation. Thermal characterization involved a novel low-scale thermal chamber to measure U-value, thermal conductivity, heat storage capacity, and dynamic thermal response. Results showed incorporating PCM decreased the U-value by 2% compared to standard gypsum boards. Additionally, PCM inclusion increased heat storage capacity by around 45% and improved dynamic thermal characteristics by decreasing thermal stability coefficient from 0.92 to 0.76 and increasing thermal lag from 0.27 to 0.49 h. The 45% increase in heat storage capacity of Comfortboard23 could lead to a 10–20% reduction in heating and cooling energy consumption, improved thermal comfort, and potential HVAC downsizing. Exact benefits depend on climate, building design, and occupancy patterns, necessitating further research in diverse real-world settings. The findings demonstrate Comfortboard23’s potential for enhancing thermal energy storage in buildings, contributing to energy savings, improved thermal comfort, and reduced temperature fluctuations across varying daily temperatures. Overall, the study highlights the promise of Comfortboard23 as an energy-efficient PCM-integrated building material.

Real-Time Indoor Environmental Quality (IEQ) Monitoring Using an IoT-Based Wireless Sensing Network.

In recent years, our time spent indoors has risen to around 90% and to maintain an occupant's comfort and well-being, Indoor Environmental Quality (IEQ) is monitored. Concerned with inhabitant's satisfaction and health, the adoption of smart solutions for IEQ monitoring and improvement has expanded. The solution this study explores is an occupant-centric approach involving the implementation of an Internet of Things (IoT) IEQ sensing network in a prominent office skyscraper in Hong Kong. Over the course of 15 months, real-time IEQ data were collected from 12 locations within the building. The data were collected at 1-min time intervals and consisted of readings of indoor air temperature, radiant temperature, relative humidity, air velocity, carbon dioxide (CO2), particulate matter (PM10 and PM2.5), horizontal illuminance levels, and sound pressure levels, which served as the basis of the assessment made about the qualities of thermal comfort, indoor air quality (IAQ), aural comfort, and visual comfort. Compared to traditional periodic surveys, this IoT-based sensing network captured instantaneous environmental variations, providing valuable insights into the indoor environment's spatial characterization and temporal dynamics. This smart solution also assisted facility management in terms of identifying sources of discomfort and developing effective mitigation strategies accordingly. This study presents an occupant-centric approach to improve occupant comfort and energy efficiency within office buildings. By customizing the built environment to enhance occupants' well-being, comfort, and productivity, an emphasis is placed on a more personalized and occupant-focused design strategy. This approach integrates technical design with human experience, highlighting the importance of real-time physical and subjective surveys for achieving optimal results.

Development and performance evaluation of an indoor thermal environment control algorithm incorporating MET estimation model with object detection

As people increasingly spend time indoors, the significance of the indoor environment in influencing occupant quality of life is becoming more pronounced. Traditionally, indoor environment control primarily relied on fixed temperature settings, which failed to accommodate the diverse circumstances of occupants. This approach limited the creation of a comfortable indoor environment and the enhancement of energy efficiency. Consequently, there is growing interest in occupant-centric control (OCC), which integrates metabolic rate (MET) information, which is a critical factor in determining the thermal sensation of occupants. Previously, a method was developed to estimate MET by classifying occupant poses and detecting the objects they interact with from indoor images. This study aims to develop and experimentally validate an indoor thermal environment control algorithm (ITEC-algorithm) using the MET estimation model and assess its effectiveness and applicability in real building environments.The performance evaluation revealed that the ITEC-algorithm significantly enhanced the comfort ratios, achieving improvements of up to 59% compared to the fixed temperature control and 28% compared to the control methods that only used the pose classification model for MET estimation. The energy consumption varied depending on the activity and control method, with a reduction of up to 88% compared to fixed temperature control. These results indicate that thermal comfort can be enhanced while minimizing unnecessary energy consumption by incorporating the MET of the occupants. Consequently, it has been confirmed that the ITEC-algorithm effectively improves thermal comfort by managing the MET of various occupants.

Innovative passive techniques and PCM integration in building envelopes for enhanced energy efficiency in desert regions

Rising energy demands in buildings for heating, cooling and operating appliances underscore the importance of implementing energy-efficient solutions. Passive cooling techniques provide a sustainable alternative to conventional, energy-intensive cooling systems, promising reduced energy consumption in buildings. Using a dynamic heat transfer model validated with ANSYS Fluent, this study examined three configurations: integrating phase change materials at the brick's centerline with cavities filled with air, EPS insulation, and emissivity coating. Additionally, the benefits of combining all three passive methods were evaluated. Results indicated that among the evaluated PCMs, capric acid demonstrated superior performance. While each passive method studied offers distinct advantages in enhancing thermal performance and achieving energy efficiency, assessing their combined effects revealed significant insights. Specifically, integrating capric acid at the brick's centerline, while simultaneously configuring EPS insulation in the upper cavities and emissivity coating in the lower cavities, yielded superior performance. This configuration significantly reduced inner surface temperature by approximately 6.6 °C and minimized heat flux by about 58.4 % compared to traditional bricks. Achieving energy savings of 56.24 %, this configuration shows potential to enhance both thermal comfort and energy efficiency in building applications.

Environmental and energy analysis of the renovation of social housing buildings under various climate change scenarios and user profiles

The renovation of social housing buildings, a priority for the European Union, must be assessed under a Climate Change (CC) context. This work, centred on the user and the environmental impact, analyses the climate resilience of the renovation of the social housing building stock of the Basque Country, located in Northern Spain. In this region, characterised by cold winters and mild summers, CC projections indicate a moderate warming even in the worst-case scenario. The assessment of passive renovation actions indicates that reducing heating demand is key no matter the CC scenario. The reduction achieved in heating demand with deep passive renovations is up to 82.2 % when the worst CC scenario is considered. Indeed, since low-income tenants occupy these buildings, it has been found that global warming would help users achieve indoor standard conditions in a more effective way than with passive renovation actions. Consequently, to improve indoor conditions independently of the CC scenario, active renovation measures must also be considered. Furthermore, the thermal comfort analysis proved that the risk of overheating in this region is negligible, with less than 4 % of the yearly hours above 26 °C. Finally, the Life Cycle Impact Assessment shows that the environmental impact of the renovation is short when compared to the impact of the operational stage. The use of conventional or ecological materials during renovation would save up to 6.5 % of Non-Renewable Primary Energy Consumption and 3.7 % of CO2 emissions during the life-cycle of the building.