Thermal Comfort Requirements Research Articles

Investigation on the Influence of Rural Residents' Behavior Regulation on Gas-Fired Combi-Boiler Heating in Northern China

Abstract There is basically no research on the impact of rural residents' behavior on heating when using gas-fired heating and hot water combi-boilers as a heat source. Two residential buildings in rural areas of Handan were selected for the study, indoor and outdoor temperatures and gas consumption were tested, and a survey of residents' behavior was conducted. The results show that the ratio of actual heat inputs to rated heat input in two buildings is 47–76% and 25–91%, indicating that the reason for the indoor temperature being lower than design temperature is not the insufficient heating capacity of the heating system, but rather the result of residents actively adjusting the combi-boilers. Resident behavior adjustment has a significant impact on the temperature difference between indoor and outdoor and gas consumption for heating. Compared to the automatic adjustment behavior mode, the maximum deviation of the temperature difference between indoor and outdoor under artificial adjustment behavior during period 1 is 59%, with an average deviation of 44%. However, the average gas consumption is reduced by 9.2%. The study reflects that rural residents actively adjust the gas-fired combi-boilers to significantly reduce the gas cost of building heating while meeting their own thermal comfort requirements.

Role of phase change materials and digital twin technology in thermal energy storage system: A review

The exponential growth in energy consumption and demand, along with the depletion of natural resources, is exerting a catastrophic impact on global ecosystems. Recent advances in research and development have focused on the distribution of renewable energy sources and the reduction of traditional energy usage as strategies to address pressing environmental concerns, such as climate change and global warming. Moreover, there is an urgent need for appropriate technologies that can enhance the thermal performance of buildings, given the rapid increase in global cooling and heating demands. This study examines the role of phase change materials (PCMs) and digital twin (DT) technology in thermal energy storage (TES), drawing on an analysis of 89 research articles sourced from multiple databases and references. The findings demonstrate that TES systems optimized through meticulous selection of PCMs can effectively meet thermal comfort requirements. Integrating DT technology with building systems allows for the analysis of cooling effects and optimization of energy demand through DT models of smart buildings. The present study provides a comprehensive overview of the different PCMs used in cooling applications and explores the implementation of DT technologies within building systems. In addition, practical applications of DT technologies for TES systems are presented, providing insights into their potential for enhancing energy efficiency in building systems.

AI-Based Controls for Thermal Comfort in Adaptable Buildings: A Review

Due to global weather changes and pandemics, people are more likely to spend most of their time in indoor environments. In this regard, indoor environment quality is a very important aspect of occupant well-being, which is often ignored in modern building designs. Based on our research, thermal comfort is one of the essential items in building environments that can improve the mental stability and productivity of the occupants if the building’s indoor environment is created in a way that meets the occupants’ comfort requirements. Buildings nowadays operate on adaptive or stationary models to attain thermal comfort, which is based on Fanger’s model of the Predicted Mean Vote (PMV). Based on the literature review, limited work has been carried out to enhance the quality of the inside environment, and most research work has been devoted to building energy management. Moreover, there have been no definite solutions so far that have the capability to detect the thermal comfort requirements of multiple occupants in real time. Modern buildings tend to operate on predefined set point parameters to control the indoor environment based on the measured room temperature, which can be different from the thermal comfort requirements of the occupants. This paper discusses the limitations and assumptions that are associated with the existing thermal comfort solutions and emphasises the importance of having a real-time solution to address the thermal requirements of occupants.

Lab study on the physiological thermoregulatory abilities of older people with different frailty levels

The advent of an aging society has increased the need for a better understanding of thermal comfort requirements, especially for older people's health. Differences in thermal comfort needs among older individuals with varying frailty levels are noted, but the impact of health on physiological thermoregulation is underexplored. This study, based on the frailty classification method characterized by Fried, selected 12 non-frail (age:71.00 ± 5.41) and 12 pre-frail (age:72.68 ± 5.7) older individuals for laboratory experiments. This experiment set sudden temperature change experiments to illustrate differences in subjective perceptions and physiological changes between non-frail and pre-frail older people. Results show that non-frail individuals are more likely to complain in warmer environments. Significant differences in perception only emerged when the temperature differential between neutral and warm conditions exceeded 5 °C. Pre-frail individuals exhibited slower skin temperature changes and required more time to stabilize with the environment, particularly in the foot. Pre-frail individuals tend to sweat less in changing environments and require more time to reach stable sweating. There is positive evidence indicating that heart rate of pre-frail individuals is higher than non-frail individuals, with different changing trends observed between the two groups. When the temperature difference exceeds 5 °C, the pulse intensity trend in pre-frail individuals diverges from that of non-frail individuals. In controlling indoor environments for older people, it is essential to consider both subjective comfort and physiological thermoregulation capabilities. For older adults with frailty characteristics, applying localized warming, using small temperature differences, gradually adjusting the environment may better meet their comfort needs.

Energy analysis of standalone hybrid active solar room heating system

AbstractIn winter, offices use heat pumps, electric heaters, and blowers to stay warm, but these use traditional energy that is not sustainable or eco‐friendly. To meet the requirements of thermal comfort, an environmentally friendly and self‐sustainable system was developed at Madhav Institute of Technology and Science in Gwalior, India. This system includes a heat exchanger, a flat plate collector, an evacuated tube collector, and a pump. Two versions of the system were tested: one with a heat exchanger and an evacuated tube collector (HEWETC) and another with a heat exchanger and a flat plate collector (HEWFPC). The results showed that the HEWETC system is better at heating the room and has higher efficiency compared to the HEWFPC system. The HEWFPC system is 12% efficient, while the HEWETC system is 21% efficient. The room stayed at a constant temperature of 26.3°C all day. The HEWETC and HEWFPC systems provided 0.46 and 0.55 MJ of heat to the room, respectively. During the heating season, the solar heat collected was 8030.38 kWh, and electricity used was 5229.7 kWh. The HEWETC system proved to be effective and suitable for heating the building.

Towards various occupants with different thermal comfort requirements: A deep reinforcement learning approach combined with a dynamic PMV model for HVAC control in buildings

Reinforcement learning (RL) has great potential in achieving energy-efficient, comfortable and intelligent control of heating, ventilation and air conditioning (HVAC) systems. Although research on RL-based HVAC control has attracted increasing interest, current studies generally use simple building simulation as the environment to train agents, and the definition of thermal comfort is limited to a wide temperature range, which cannot meet the different thermal comfort requirements of various occupants. This study proposes a deep reinforcement learning (DRL) control framework based on the Dueling Deep Q-network (DQN) algorithm, combined with a self-designed environmental model and reward function, for HVAC control meeting different thermal comfort requirements. Specifically, based on the theory of building thermal dynamics, a nonlinear equation modified by experimental data is used for the environmental model that reflects the actual thermal change of building. Different thermal comfort requirements are considered and analysed through a dynamic predicted mean vote (PMV) model that focuses on the metabolic rate and clothing level of occupants. By systematically exploring different heating modes for occupants and control time intervals, the proposed framework demonstrates that heating energy consumption can be reduced by 4.8%-39.58% under various conditions compared to rule-based control. In addition, the study found that the HVAC control based on DRL has greater potential in saving energy when the heating demand of building is higher. Our study is helpful for researchers to make HVAC control more energy-efficient and user-friendly with the help of artificial intelligence.

Effect of Passive Energy Efficiency Measures in Designing Sustainable Primary Healthcare Facilities in Nigeria

This study aims to develop a design for a sustainable healthcare centre through passive energy efficiency measures to improve the thermal comfort, cooling, lighting and ventilation requirements for primary healthcare centres in Nigeria. The methodology adopted for the study included both primary and secondary data collection. Primary data were collected from the administered questionnaire (5-point Likert scale closed-ended), a total of 350 sets of questionnaires administered and 87% were valid. A case study research strategy was adopted to ascertain the effectiveness and efficiency of building design with an emphasis on sustainable architectural design principles. A significant regression equation was revealed (F (2,257) = 33.619, p <.000, with an R2 of 0.294, which revealed that implementing passive measures for energy optimization has a significant and positive effect on designing sustainable healthcare centres. It further recommends the integration of passive design, design for deconstruction, adaptive reuse, and design for human comfort as part of architectural design principles that would result in sustainable energy optimization should be adopted in every design of primary healthcare centres by architects.

Assessing the Impact of Climate Changes, Building Characteristics, and HVAC Control on Energy Requirements under a Mediterranean Climate

Assessing the Impact of Climate Changes, Building Characteristics, and HVAC Control on Energy Requirements under a Mediterranean Climate

Optimizing Solar Heating for Thangka Exhibition Halls: A Case Study in Malkang Cultural Village

With the continuous development of rural revitalization and urbanization in China, the sustainable transformation of traditional rural architecture has become increasingly important. This study takes the Thangka exhibition hall in rural Malkang, Sichuan Province, as the research object and proposes a Thangka exhibition hall architectural design centered around solar heating and aiming for near-zero energy consumption. The research method involves establishing a solar energy system model on the roof of the exhibition hall and utilizing solar angle and area calculation formulas along with simulation software to calculate the optimal installation angle and area of solar panels, with the aim of achieving indoor temperatures that meet Thangka protection requirements while achieving zero-energy heating. Preliminary results indicate that this solar-centric near-zero energy architectural design can effectively promote the increase in indoor temperature through solar thermal conversion. Additionally, through calculation and simulation, the optimal installation angle for the solar panels achieving zero-energy heating is determined to be 24.25 with an azimuth angle of −1.2. The optimum installation area for solar panels is 8.2 square meters in the showroom and 2.7 square meters in the storeroom. Among these, the solar panel area for the Thangka exhibition hall constitutes 4.12% of the total area and is required for maintaining Thangka protection temperature requirements throughout the year, while the solar panel area for the storage room constitutes 1.88% and is also needed for the same purpose. Studying the optimal installation angle and area of solar panels can transform the exhibition hall into a near-zero-energy building, meeting the temperature requirements for Thangka preservation and human thermal comfort, while also achieving optimal economic benefits. This provides guidance and a reference for promoting near-zero-energy buildings in rural areas.

Direct load control-based optimal scheduling strategy for demand response of air-conditioning systems in rural building complex

The abrupt surge in electricity consumption for air-conditioning (AC) in rural areas has exacerbated the rural power supply and demand imbalance, presenting a significant challenge to the reliability and stability of power provision in rural low-voltage grids. Implementing power demand response (DR) in buildings is recognized as an effective solution to address the grid's power imbalance and reliability issues. Among various building DR strategies, direct load control (DLC) stands out as a proficient approach to rapidly curtail building AC loads. However, applying this method solely to individual rural buildings proves less effective in peak regulation (PR). To fully exploit the DR potential of AC systems in rural building complex, it is essential to scale up the application of DLC. Consequently, a DLC-based DR optimal scheduling strategy is proposed for rural building complex AC systems. This strategy aims to meet PR demand and maximize the benefits for load aggregator. It establishes four DLC methods and differential compensation mechanisms, taking into account the varying thermal comfort requirements of AC users. The DR optimization model is solved using a genetic algorithm (GA), with PR demand derived from long and short-term memory neural network predictions. To validate the proposed strategy, a simulation study is conducted on a 200-unit farmhouse AC system, utilizing a typical rural soil source heat pump system in Xi'an, Shaanxi Province. The results demonstrate that the strategy surpasses the PR target by approximately 6.65 % during the DR period, while ensuring a minimum level of thermal comfort for all user categories. Additionally, it yields a PR benefit of 88.73 yuan per day for all users, thereby promoting the adoption of clean energy in rural areas.

The impact of thermal comfort requirements on household heating energy consumption

Urban residential buildings consume a large amount of energy. In most homes, heating runs on a set schedule. Therefore, the installation continues to operate irrespective of whether the residents' thermal comfort requirements have been fulfilled. This process results in considerable wasted energy and CO2 emissions. To address this issue, in this study, data on heating energy use and carbon emissions from 2302 field surveys in the core, main, and suburban areas were quantified. Furthermore, the impact of different thermal comfort requirements on the carbon emissions of self-heating households was explored based on the PMV-PDD model. The study revealed that (1) Beijing's per capita household energy consumption is 613.80 kgce·a−1, and heating accounts for a significant portion of energy consumption and carbon emissions; (2) carbon emissions from household energy consumption differ among districts in Beijing, with suburban districts emitting approximately 1.6 times more than main urban areas; (3) suburbs have less need for thermal comfort, but they emit more carbon than other areas with similar heating costs due to limited heating infrastructure, poor access and the high cost of clean energy; and (4) warmer thermal comfort requirements elevate energy consumption and thus positively impact heating costs and carbon emissions, especially in the main urban area. The energy waste caused by heating is quantified, and the impact of thermal comfort requirements on carbon emissions is clarified. The findings are informative for optimizing energy use in residential buildings and proposing targeted low-carbon heating policies.

Data-driven flexibility evaluation methodology for community integrated energy system in uncertain environments

Flexibility operation and evaluation have become central and critical for grid integration of high percentage of renewable energy generations (REGs). However, the interactions between multiple energy forms in community integrated energy system (CIES) and the uncertainty of REG significantly complicate the quantification of flexibility. To this end, a novel two-stage data-driven flexibility evaluation methodology is proposed for CIES. The first stage performs optimal scheduling of multiple flexible resources, where the flexible thermal comfort requirements of users in integrated response demand are considered by introducing a predicted mean vote index. The second stage refines the flexibility supply model for flexible resources, and carves out the system flexibility supply domain by enveloping the net load. To overcome the uncertainty of REG, a data-driven scenario analysis approach is developed, which fully captures the renewable output characteristics under different climate environments and avoids complicated explicit feature model construction. Furthermore, a set of evaluation metrics is proposed from the aspect of direction, amount, and frequency to quantify the flexibility. The effectiveness and accuracy of the proposed methodology are verified by applying it to a modified CIES located in North China. The sensitivity analysis of multiple time scales and flexible resources to operational flexibility and economy of CIES is presented, which provides guidelines for the efficient allocation of flexible resources and expand planning of CIES.

Impact of Energy-Consuming Air Conditioning Systems on People's Thermal Comfort and Preferences: Comparative Study of Iraq and Gulf Cooperation Council Countries

This study investigates the impact of the intense usage of air-conditioning systems on the thermal comfort requirements of building occupants. It compares the thermal comfort requirements of building occupants in Iraq and Gulf Cooperation Council (GCC) countries. Iraqis have limited usage of air-conditioning units, whilst people in GCC countries intensely operate these systems. Research work underpinning this article involved undertaking a year-long thermal comfort survey in Iraq, and an intensive analysis of thermal comfort studies conducted in GCC countries. Results show that, in Iraq, people experience a 2–50 °C annual indoor temperature range, and their annual comfort range is 14–35 °C. In GCC countries, due to the intense usage of air-conditioning systems, the widest recorded annual indoor temperature range is 17.2–31.0 °C, and the widest annual comfort range is 20.0–27.8 °C. These results demonstrate the significant impact of air-conditioning systems on narrowing the thermal comfort limits of building occupants leading to high energy consumption. This study presents a novel comparison between two cases highlighting the impact of air-conditioning systems on the thermal comfort requirements of building occupants. The results of this study can be used to inform the development of thermal comfort standards that better consider people’s adaptation capabilities to help reduce energy consumption for heating and cooling purposes.

Thermal comfort in school children: Testing the validity of the Fanger method for a Mediterranean climate

Thermal comfort is an essential factor when designing or refurbishing schools because it helps to improve wellbeing and academic performance. However, little attention has been paid to assessing the thermal comfort level of children. Previous studies on thermal comfort have mainly focused on adults' perceptions, extrapolating their results to all ages without cross-checking them for relevance. The aim of this research was to determine whether children perceive temperature in a similar way to adults and if their thermal comfort limits are the same. A school in south-eastern Spain was selected as the case study. Thermal comfort surveys of children were conducted and compared with analytical calculations obtained using the Fanger method. The results showed that the Fanger method was not valid for the estimation of children's thermal comfort, especially in girls and younger children. The novelty of this research demonstrates that children have specific thermal comfort requirements that are not covered by current standards and calculation methods, such as the Fanger method. Analysis also determined the correction coefficients necessary for adapting Fanger's analytical method to children according to age and gender in BShs climate.

Indoor thermal nonuniformity of atrium-centered public building: Monitoring and diagnosis for energy saving

Heating ventilation and air conditioning system accounts for over one third of building energy usage, especially for public buildings due to large indoor heat source and high ventilation and thermal comfort requirement compared to residential buildings. Natural ventilation shows high application potentials in public buildings because of its high-efficient ventilation effect and energy saving potential for indoor heat dissipation. In this paper, the building design is conducted for a science museum and library with atrium-centered natural ventilation consideration. The floor layout, building orientation and internal structure are optimized to make full use of natural ventilation for space cooling under local climatic conditions. A natural ventilation model is established through building field tests to evaluate the air flow and thermal environment under indoor and outdoor pressure differences. The preliminary results show that Building A's courtyard exhibited overheating issues, likely attributed to outdoor solar radiation, whereas Building B's courtyard experienced localized cooling, possibly due to indoor air conditioning system controls. Addressing these concerns necessitates modifications in courtyard design and structure. Moreover, both courtyards displayed vertical temperature gradients, emphasizing the need for effective management of outdoor heat influx and enhancements in indoor ventilation and shading strategies. To mitigate these issues, the study proposed three distinct roof design models and more refined indoor air conditioning system control strategies. The optimization of architectural design can achieve a maximum energy-saving rate of 46.54 %. Furthermore, aligning functional zones with thermal comfort areas was recommended to enhance overall building thermal comfort. The findings and proposed solutions from this study are anticipated to contribute to the enhancement of thermal comfort, energy efficiency, and vertical temperature distribution in large public buildings, catering to user requirements while reducing energy consumption. This research holds significant implications for advancing sustainability and environmental preservation in the realm of architecture.

Natural Ventilation for Cooling Energy Saving: Typical Case of Public Building Design Optimization in Guangzhou, China

Heating ventilation and air conditioning systems account for over one-third of building energy usage, especially for public buildings, due to large indoor heat sources and high ventilation and thermal comfort requirements compared to residential buildings. Natural ventilation shows high application potential in public buildings because of its highly efficient ventilation effect and energy-saving potential for indoor heat dissipation. In this paper, a building design is proposed for a science museum with atrium-centered natural ventilation consideration. The floor layout, building orientation, and internal structure are optimized to make full use of natural ventilation for space cooling under local climatic conditions. The natural ventilation model is established through computational fluid dynamics (CFD) for airflow evaluation under indoor and outdoor pressure differences. The preliminary results show that such an atrium-centered architectural design could facilitate an average air exchange rate over 2 h−1 via the natural ventilation effect. Moreover, indoor thermal environment simulation results indicate that the exhaust air temperature can be about 5 °C higher than the indoor air mean temperature during the daytime, resulting in about 41.2% air conditioning energy saving ratio due to the free cooling effect of natural ventilation. This work can provide guidance and references for natural ventilation optimization design in public buildings.

Intelligent optimization for building energy management considering indoor heat transfer

<p>To achieve green and low-carbon goals in the building energy sector, precise energy management strategies are essential to support user comfort and energy-saving needs during operation. However, the thermal comfort requirements of building users may conflict with societal demands for low-carbon and energy efficiency. This creates a challenge between the precision of energy use models and the speed of energy management strategies. It is necessary to combine the advantages of building physical models and deep reinforcement learning to develop faster and more accurate energy management strategies. This paper proposes a smart energy management optimization for buildings, considering indoor heat transfer. First, a third-order heat transfer model for rooms is constructed to quantify the heat transfer between them. Next, a detailed model of the central air conditioning system is developed, considering the relationships between its internal components. To achieve green and low-carbon building operations while maintaining user comfort, a multi-objective optimization algorithm based on deep policy gradient decision-making is proposed. The method is validated on actual building energy systems using real data with 15-minute resolution. We find significant differences in heat transfer between different rooms within a building, and the proposed intelligent energy management optimization method effectively balances low-carbon, energy-efficient operation with user comfort.</p>

Effects of different zoning thermostat controls on thermal comfort and cooling energy consumption in reading rooms of a library

This study assessed thermal comfort and energy consumption in indoor environments controlled by air or operative temperature. Reading rooms in a library were divided into several zones based on the distribution of operative temperature. Using air temperature of the inner zone in thermostat control yielded the lowest energy consumption but the poorest thermal comfort level. Conversely, using operative temperature of the least favorable exterior zone resulted in higher energy consumption and comfort levels. The suggested optimal control based on switching boundary temperature minimized energy consumption while satisfying the thermal comfort requirement. The switching boundary temperature range on the top floor is 0.7 °C lower than on the middle floor due to the influence of the roof. The thermostat control modes had similar effects on the east and west reading rooms. The switching boundary temperature ranges of north room was 2.0 °C higher than those of the south room. Zoning control using air temperature control in the inner zone and operative temperature control in the exterior zone was recommended as a much simple mode to keep thermal comfort with low energy use. This study provides insights about the use of operative temperature in zoning thermostat control and theoretical guidance for practical implementation.

Subzone division optimization with probability analysis-based K-means clustering for coupled control of non-uniform thermal environments and individual thermal preferences

Collective air distribution is widely used for thermally comfortable indoor environments but is limited to unified thermal comfort requirements. Advanced collective air distribution has the potential to generate non-uniform thermal environments for individual thermal preferences. This study proposes a subzone division optimization method for nonuniform thermal environments to improve thermal preference satisfaction. The proposed method divided non-uniform thermal environments into subzones using probability analysis-based K-means clustering, minimizing and maximizing the thermal environment differences within and among the subzones, respectively. The number of subzones was determined to maximize thermal preference satisfaction with the coupled control between the nonuniform environments and individual thermal preferences while limiting the percentage of thermal discomfort. The results based on experiments of advanced collective air distribution, i.e., stratum ventilation, showed that thermal preference satisfaction and the percentage of thermal discomfort increased with an increasing number of subzones. Compared with the conventional method (i.e., uncoupled control without subzone division optimization) and recent method (i.e., coupled control without subzone division optimization), the proposed method improved the thermal preference satisfaction by 34.7 % and 11.7 %, respectively, for four subzones. Moreover, with the proposed method, increasing the system control flexibility increased thermal preference satisfaction. Compared with the variable air volume system, the constant air volume system and the system with variable supply airflow rate and temperature improved thermal preference satisfaction by 5.8 % and 22.5 %, respectively. The proposed method contributes to extending the capability of collective air distribution for individual thermal preferences.

Building Optimisation Vis-À-Vis Solar Shading for Improved Comfort and Energy Efficiency in Classrooms

Excessive solar radiation negatively affects classroom occupants' perfor­mance and thermal comfort, especially in buildings with West and East-facing glazed openings. This study utilises fixed external shading devices and triple-glazed low-emissivity windows to optimise a classroom building in Nigeria. Employing hybrid ventilation mode in EnergyPlus simulations, the optimised model shows a 44% reduction in discomfort hours, a 23% decrease in cooling load, and a 16% drop in energy demand compared to the original design. Comparative analysis of the optimised model with the as-built and West-East oriented classroom reveals a 16% and 10% reduction in energy consumption per conditioned area, along with 56 KWh/m² and 32 KWh/m² savings in cooling demand, respectively. Despite the effectiveness of fixed shading in curbing solar gains, occasional glare persists. This research underscores that shading alone may not fully meet thermal comfort requirements, emphasising the importance of building fabrics, building orientation and climate-sensitive design.