Thermal Comfort In Buildings Research Articles

Thermal comfort and adaptive behaviors in office buildings: A pilot study in Turpan (China) during summer

Nowadays, evaporatively cooled office buildings commonly observed in dry hot areas in summer of China. However, few dedicated studies to record the local residents' thermal comfort and adaptability in these buildings. The contribution of adaptive comfort theory on thermal perception still remains unclear for optimizing office building design parameters. Hence, to deeper probe the adaptive thermal comfort of the related indoor environment, a field study of office buildings during summer considering evaporative cooling air conditioned (ECA) and naturally ventilated (NV) mode was conducted in Turpan, China. Based on 931 valid datasets collected from questionnaires, we found that the neutral temperature (Tn) of 28.4 °C in ECA group, 0.6 °C lower than NV group (29.0 °C). A lower air temperature (Ta) and higher humidity (RH)/air-velocity (Va) were expected in two modes, and Va has a stronger influence than RH on mean thermal sensation votes (MTSV). Meanwhile, occupants can adapt to current indoor environment through physiological, psychological and behavioral adjustments, while the clothing regulation had limited effect on MTSV unless the outdoor temperature exceeds 38 °C. Whether in ECA or NV mode, the predicted mean votes (PMV) model overestimated actual thermal sensation when operative temperature (Top) beyond 28 °C. Adaptive models were also proved varied from that in current standards, which indicated that they were not suitable for evaluating the studied buildings in Turpan. Above findings could suggest us a better understanding of the occupants' thermal adaptability, thereby providing the reference of design parameters revision and passive strategies for local newly/renovated buildings.

Experimental investigation of dynamic wind tower augmented with solar heating unit for improved thermal comfort in buildings during cold conditions

Wind towers have been used in buildings for centuries to harness natural airflow and ventilation. Their usefulness comes from their capacity to absorb wind energy and direct it into interior areas, promoting airflow and exchange. Scientific evidence shows that buildings are a substantial contributor to global warming and energy use. HVAC systems contribute to a significant percentage of this energy demand. In this situation, using wind towers to reduce greenhouse gas emissions is a viable and cost-effective option.In this work, a novel approach of integrating a rotation unit into the wind tower was carried out to enhance the performance. By enabling the wind tower to rotate and align with the direction of maximum wind velocity, the system could optimize the ability to capture the wind lead up to enhanced ACR and improved indoor air quality. This study further incorporates two solar heating units (SHU) to heat the incoming fresh air, which can reduce the thermal load on conventional heating systems.Through comprehensive measurements and analysis, this work studied the performance of the wind tower system under different wind velocities and solar radiation levels. The results showed that the rotation unit (RU) increased the average Air Change Rate by as much as 61%. Due to the incorporation of SHU and RU, the overall average temperature inside the test room increased by 6.09%. Also, the average velocity intake in the wind tower rose by 15–30% due to the RU. The findings discussed in this paper provide valuable insights for architects, engineers, and researchers involved in designing and optimizing ventilation and heating systems, paving the way for more environmentally friendly and comfortable living environments.

Energy Implications of Thermal Comfort in Buildings Considering Climate Change

Extreme weather events and rising global temperatures are signs of the urgent threat that climate change poses to our planet [...]

Implementation of Building a Thermal Model to Improve Energy Efficiency of the Central Heating System—A Case Study

This paper presents the concept of an innovative control of a central heating system in a multifamily building based on the original thermodynamic model, the resulting architecture of the control system, and the originally designed and manufactured wireless temperature sensors for thermal zones. The novelty of this solution is the developed layers of the control system: distributed measurement and correction analysis, which is based on the existing infrastructure and the local HVAC controller. This approach allows for the effective use of the measured temperature data from thermal zones and finally sending the value of the calculated correction of settings to the controller. Moreover, in the analytical layer, a model was also implemented that calculates the necessary amount of energy based on data from the subsystem of temperature sensors located in the thermal zones of the building. The use of the algorithmic strategy presented in this paper extends the functionality and significantly improves the energy efficiency of the existing, classic, reference heating control algorithm by implementing additional control loops. Additionally, it enables integration with demand-side response systems. The presented concept was successfully tested, achieving real energy savings for heating by 12%. These results are described in a case-study format. The authors believe that this concept can be used in other buildings and thus will have a positive impact on the energy savings used to maintain thermal comfort in buildings and significantly reduce CO2 emissions.

Enhancing energy efficiency and thermal satisfaction in office buildings: A comprehensive evaluation of space match strategy

Efforts have been made to balance energy efficiency and thermal comfort in buildings. Heating, ventilation, and air conditioning (HVAC) strategies incorporating occupant-based predictive models and personal comfort systems, have been proposed based on conventional workplaces with fixed workstations. However, the growing popularity of flexible working arrangements, where occupants can choose their preferred workstations, presents new challenges. Recent studies have explored personalized space match strategies that leverage occupant preferences and the varying thermal conditions within a building, aiming at optimizing thermal satisfaction without excessive energy consumption through reallocating occupants. However, the overall impacts of these strategies at the whole building level have not been quantified in existing literature. This study aims to comprehensively evaluate the energy performance and thermal satisfaction of space match strategies in typical office buildings. We generate 660 occupant profiles and integrate them into EnergyPlus for analysis. Our findings indicate energy savings ranging from 2.2% to 25.3% and comfort improvements ranging from −0.9% to 15.7%. Furthermore, we introduce two setpoint strategies: energy-driven and comfort-driven, which provide quantitative insights into the tradeoffs between energy and comfort. These findings not only assist operators in making informed decisions but also support the adoption of space match strategies in real-world office spaces.

Design Procedures of Double-Skin Façades for Achieving Internal Thermal Comfort in Educational Buildings

Design Procedures of Double-Skin Façades for Achieving Internal Thermal Comfort in Educational Buildings

Phase change materials embedded in expanded clay aggregates to develop energy storage concrete: A review

Thermal energy storage (TES) based on phase change materials (PCM) is an effective strategy to reduce energy consumption in buildings. The efficient implementation of TES in building through PCMs, requires modification of their thermal performance, appropriate design and evaluation of their thermal and economic efficiency. One major challenge in the application of PCMs is the selection of high-performance and environmental-friendly supporting materials to overcome the most critical drawback of PCMs (solid-to-liquid transition and resulting leakage). This review focuses on expanded clay (EC) lightweight aggregate (LWA), as one of the promising supporting materials for development of form-stabilized PCM (FSPCM) in the lightweight concrete (LWC) industry. The large specific surface area and porous structure of expanded clay can maintain considerable amount of PCM. In addition, mechanical properties and compatibility with various PCMs make EC a suitable carrier. A detailed review of available researches is presented to elucidate the properties of PCMs embedded in EC for thermally efficient cement-based concrete. Various combinations of EC with the most used PCMs, thermal and mechanical properties of matrices containing PCM-EC, strategies to improve the efficiency of PCM performance, and finally the impact of PCM-EC based concretes on the thermal comfort of buildings are critically summarized.

Integration of Solar Cooling Systems in Buildings in Sunbelt Region: An Overview

This paper presents the results of the activities related to the subtask “Building and process optimization” of the IEA SHC Task 65. The main topic of this activity was the integration of solar cooling in retrofitted HVAC systems. Based on the current conventional HVAC systems, the integration may present difficulties concerning cold distribution and refrigerants. Cold supply systems can also reduce airflow in air-based systems and enhance thermal comfort in buildings. The best technical actions for specific scenarios were mentioned considering both technical and economic aspects. Unfortunately, not all the analyses that were planned provide useful data. Results show that there are few recent projects that consider the application of solar cooling systems in buildings and most of them are based on simulation. Moreover, not much data about the characteristics of the buildings (envelope, other cooling systems, comfort conditions, etc.) are reported in the studies. This is because many of them are more focused on the plants’ configurations, and the performance of the different plants is in general assessed by testing the prototype in a single room. Despite this, the information provided could be used as baseline cases in order to study the potential energy savings achievable by applying solar cooling systems.

Performance assessment of capric acid-ethyl alcohol/expanded vermiculite phase change material incorporated cement mortar for thermal insulation in buildings

Due to global warming, the construction sector is looking for newer materials that can be incorporated into buildings to improve occupant thermal comfort while reducing energy consumption. The ability of construction materials to store thermal energy can be enhanced by incorporating phase change materials (PCM). A PCM is a substance that releases and absorbs energy at phase transition temperatures to offer useful heating or cooling. The addition of PCM in construction materials for thermal insulation has been proven beneficial by many researchers. The current study explores the feasibility of the incorporation of an organic PCM composite, which is developed by impregnating expanded vermiculite (EV) with capric acid (CA) using ethyl alcohol (EA) under vacuum conditions in cement mortar. Cement mortar mixes with EV, CA-EA/EV based PCMs, and PCMs with partially added nano silica and coir fiber combinations (PSC) were prepared by replacing fine aggregate in varied weights. Initially, the study on the primary characteristics of the developed PCM was introduced based on mechanical behavior, microstructure observations, and thermal effects. To estimate the field exposure capacity, PCM composite mortar boards were developed and tested for their physical and mechanical characteristics. Based on the findings of these tests, it was concluded that the presence of PCM improves the thermal characteristics of the mortar boards and the addition of nano silica and coir fiber enhances the physical and mechanical strength of the mortar boards. With regard to the characterization of the mortar, there was an increase in flexural strength by 8.06 % and a decrease in chloride diffusivity by 10.24 %, in water absorption by 17 %, the capillary water absorption coefficient by 8.56 % and the ultrasonic pulse velocity by 18.48 % relative to the control sample after addition of PSC into the mortar. Apart from the strength and durability studies, differential scanning calorimetry (DSC), energy-dispersive X-ray spectroscopy (EDS), thermogravimetry analysis (TGA) and scanning electron microscopy (SEM) tests were also carried out to characterize the thermal, chemical and morphological effects of the developed cementitious composite boards. As per the SEM and EDS test results, the fine aggregate replaced with 5 % of PCM in addition to nano silica and coir fiber (PSC-5 %) possesses better compatibility with the mortar by effectively penetrating through the pores. The DSC test results showed the melting and freezing point of PSC-5 % integrated mortar as 32.47 °C and 20.91 °C, respectively. A thermal conductivity value of 0.129 W/m·K also demonstrated the efficiency of PSC-5 % mortar board for maintaining better thermal comfort in buildings. The TGA assessment reported that the proposed PCM composite cement mortar board has excellent thermal durability.

From Building Information Model to Digital Twin: A Framework for Building Thermal Comfort Monitoring, Visualizing, and Assessment

The existing building stock is globally responsible for 17.5% of greenhouse gas emissions due to their operation to achieve occupant satisfaction, thus requiring a vast intervention. However, reducing building stock emissions and optimizing building energy performance cannot be considered independently by the users’ well-being. The thermal comfort conditions and their monitoring represent a central issue that could optimize building energy usage while achieving good indoor environmental conditions. This document describes the first findings of ongoing research focused on the development of a building monitoring system, based on the integration of Building Information Modeling tools and sensor technology through Dynamo Visual Programming. Starting from the development of an Asset Information Model, which represents the virtual replica of a building that currently hosts the administrative offices of the municipality of Cagliari, the first step presented in this contribution shows a thermal comfort monitoring system, scalable and modular, that allows effective gathering and elaboration of data about comfort levels in each of the building’s rooms. The system proves to be a helpful support for facility managers to control building thermal comfort conditions and HVAC systems to assure their best operative status or plan suitable interventions to achieve it.

The effect of water and vegetation elements as microclimate modifiers in buildings in hot and humid tropical climates

Thermal comfort in buildings is determined by several aspects of the climate, such as external and internal wind speeds. Therefore, this research aims to analyze the effect of water elements and vegetation as microclimate modifiers in buildings, to obtain thermal comfort through air velocity and flow analysis. In this context, the field analysis emphasized microclimate parameters. Two cases were also encompassed, namely the interior space of a residential building and a shopping center. By using field measurements with quantitative methods, data were obtained through the analysis of the PMV (thermal comfort index Predicted Mean Vote), PPD (Predicted Percentage of Dissatisfied), and TSV (Thermal Sensation Vote). This experiment was conducted to determine the influential levels of the building water and vegetation on comfort and the thermal environment. Data analysis was also processed using a statistical approach, with airflow being simulated through CFD (Computational Fluid Dynamics) method. The results showed that the air movement occurring in the building to the comfort and thermal environment, through architectural elements, reduced the temperature and humidity in the room. This was due to the heat radiation outside the building, leading to an impact on the effective air temperature for the thermal sensation of visitors. In this case, the movement of air in the building with the placement of architectural elements, such as water, vegetation, and good ventilation, was important for various activities. These activities included the following, (1) providing positive value, (2) improving the quality of the indoor environment, (3) maintaining the stability of the thermal environment at the building scale, and (4) achieving a comfortable thermal sensation.

A toolchain to evaluate the impact of urban heat island and climate change on summer overheating at district level

This paper aims to quantify and analyse the impact of urban heat island and climate change on summer indoor thermal comfort in buildings at district level. By leveraging the models of outdoor climate and dynamic building simulation, a toolchain is developed to quantify the overheating hours under different outdoor climate scenarios in rural and urban context. Future climate data are generated for the city of Roeselare (Belgium) under RCP4.5 and RCP8.5 scenarios in 2030 and 2050 respectively, and a residential district with 265 buildings is analysed by incorporating characteristics data of individual buildings, instead of using a traditional archetype approach. The results clearly demonstrate that overheating risks exist in most of the buildings of the analysed district under all climate scenarios. Mutual shading plays a non-negligible role in the overheating analysis. Scheduled opening of operable windows and controlled solar shading devices can effectively reduce the overheating hours at the district level under all climate scenarios. The impact of urban heat island is less important for the situation with adaptation measures, and the number of overheating hours could be even larger in rural areas in certain circumstances. The results of overheating hours could be different by using different quantification methods.

Energy efficiency and thermal comfort of buildings in arid climates employing insulating material produced from date palm waste matter

This study investigates the suitability of using waste material from date palm trees in thermal insulation for buildings in arid climates. Thermal conductivity was experimentally determined from a few samples of bricks containing recycled date palm fiber (DPF) and date palm spikelet (DPS). Among the samples investigated, the one containing 1.36% DPS in weight demonstrated the best characteristics for insulation purposes yielding a thermal conductivity of 0.106 W/m.K. Theoretical and experimental investigations were carried out on walls and roofs built using DPS and DPF material to see what impact it would have on energy efficiency and thermal comfort. The electricity consumption for cooling decreased by up to 64.7% and 41.2%, during the summer months, for DPS and DPF, respectively, compared to buildings erected with sand and clay. It was also concluded that the greatest amount of thermal energy entering the rooms takes place through the roofs. Four roof-materials were tested, namely: Polystyrene, Air gap, DPF, and DPP on three different days. As a thermal insulator, DPF demonstrated the best thermal comfort conditions; polyester yielded poorer thermal comfort conditions and DPP delivered rather weak results.

Occupant thermal comfort and indoor environmental conditions in Mies van der Rohe’s S. R. Crown Hall

ABSTRACT There is little empirical data in the published literature on occupant thermal comfort in buildings from the Modern Movement in architecture. We present a field survey of occupant thermal comfort and indoor environmental conditions in Mies van der Rohe’s modern S. R. Crown Hall (1956) on the campus of Illinois Institute of Technology in Chicago, IL. Surveys were deployed to 557 student participants on four separate days, including two days in the cooling season and two days in the heating season, to assess their perceptions of thermal comfort throughout the space. Indoor air temperature, relative humidity and mean radiant temperature were measured concurrently in several locations throughout the space. Occupants reported high levels of dissatisfaction with comfort in the space (percent dissatisfied ranging 37%–54%), with somewhat counterintuitive results for this building type. Overcooling was apparent during warm weather and a combination of both over- and under-heating occurred during cold weather, contrary to what was expected in this building with a high thermal transmittance enclosure. There was also high spatial variability in comfort responses and measured indoor environmental conditions. Findings highlight the need to develop contextual approaches to meeting occupant comfort needs in this building while preserving architectural aesthetics/intent.

Study on foam concrete incorporated with expanded vermiculite/capric acid PCM – A novel thermal storage high-performance building material

A major part of energy consumption is reported from the residential and commercial buildings due to the large usage of mechanical devices to maintain a comfortable indoor ambiance. Thermal conductivity of the materials used in these buildings can be reduced by using low density materials and an efficient thermal energystorage strategy. In the present paper, the thermal performance ofa building envelope was improved by incorporating phase change material (PCM) into thefoam concrete mix. At first, PCM was developed by using a light weight material, expanded vermiculite (EV) impregnated with capric acid (CA) and ethyl alcohol (EA) under vacuum conditions. Different foam composite mixes were prepared and experimentally tested. Foam concrete mixtures with EV, CA-EA/EV based PCM, and PCM with added nano silica and coir fiber combinations (PSC) were prepared by the replacement of fine aggregate (M−sand) in various weight percentages. This study reveals that PCM with a CA to EV proportion of 55% (wt.) had the maximum adsorption and stability, as assessed through liquid leakage. In addition to improving thermal efficiency, PCM enhanced foam concrete composites showed improved mechanical, hydration, durability, and thermal characteristics. In comparison to the control foam concrete and PCM foam concrete mixes, the addition of nano silica and coir fiber added foam concrete mixtures (PSC) demonstrated improved strength and shrinkage qualities. These improved properties are attributed to the pozzolanic activity of nano silica and the bridging effects resulting from the fiber to micro cracks. Apart from the durability and strength characteristics, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), differential scanning calorimetry (DSC), and thermogravimetry analysis (TGA) were adopted to characterize the morphological, chemical, and thermal aspects of the different foamed concrete mixtures. The DSC results proved that the PSC-5% foam concrete mixture had latent heat capacities of 43.90 J/g for cooling and 69.16 J/g for heating, with melting and solidification temperatures of 31.51 °C and of 21.77 °C, respectively. TGA also revealed that theproposed PCM composite has a high thermal resistance. The PSC-5% shows bettercompatibilityas perSEM and EDS tests by the proper penetration of the nano silica in the foamed compositesthrough the pores. Finally, the thermal analysis tests demonstrated that the PSC-5% has a thermal conductivity of 0.129 W/m-K, which is 49.60% lesser than the foam concrete control sample, and also possesses an improved heat storage capacity, which ensures better thermal comfort in buildings.

Balancing Thermal Comfort and Energy Consumption in Residential Buildings of Desert Areas: Impact of Passive Strategies

Modern building materials using reinforced concrete are considered the most popular in the production of housing in Algeria, specifically in desert areas such as the city of Ouargla, which is characterized by its hot and arid climate. These dwellings must be more adaptable to this difficult climate. An example is the Ouargla Ksar, which contains traditional dwellings that have proven their effectiveness in terms of the heat problem, as has been revealed in several previously conducted studies, but these dwellings have decreased in demand as they are not suitable for contemporary urban life. Therefore, the aim of this study is to improve the performance of the most recognized house typologies in the city of Ouargla in terms of thermal comfort and energy consumption by using passive strategies. In this regard, we used a research methodology based on field measurements and model simulations wherein we adopted TRNSYS 17 to determine the most often encountered problems. The simulated model was validated by statistical correlation; afterward, a simulation of a full year was run, during which many aspects of construction were studied and compared, such as insulation, the mass of the roof and walls, dimensions and types of windows, orientation, and solar shading. The results show that the studied modern house can be considered inappropriate for a desert climate, and the use of solar shading combined with insulated walls and roof allows for an increase of 35% in annual thermal comfort hours (−0.5 ≤ PMV ≤0.5) and for a 22.73% reduction in the energy consumption. We then compared the simulated scenarios with a traditional house characterized by a bioclimatic architectural design that we used as a reference building. The obtained results may be useful in guiding both refurbishment interventions on existing buildings and the design of new ones. Although the simulated interventions have been widely studied in the literature, it is very important to determine their impact on the perception of the indoor environment and on the energy consumption in this specific geographic area.

Energy modeling and predictive control of environmental quality for building energy management using machine learning

Heating, Ventilation, and Air Conditioning (HVAC) systems play a vital role in building energy management by controlling the indoor temperature and ensuring the occupant's comfort. However, the energy consumption of HVACs contributes significantly towards overall energy usage of a building and carbon footprint. To address this challenge, this research proposes the development of a predictive model for HVAC temperature forecasting using Machine Learning (ML) algorithms to optimize energy efficiency while maintaining thermal comfort in buildings. The study focuses on comparing the performance of Transformer Neural Networks and CNN-LSTM, a seq2seq model combining Convolutional Neural Networks (CNN) and Long-Short Term Memory (LSTM) on multiple forecasting horizons using data obtained from multiple devices deployed in a room verified by feedback survey forms filled by occupants. The transformer model outperformed, achieving an R2 score of 0.936 at a 1-minute forecasting horizon, surpassing the performance of CNN-LSTM model at all tested forecasting horizons. The transformer model yielded significant energy savings thereby reducing energy consumption by almost 50 % compared to the non-AI conventional methods, particularly at forecasting horizons of 1 min and 60 min, while the occupant survey also favoured a 60-minute forecasting horizon. The performance of transformer model particularly with a 60-minute forecasting horizon underscores its potential to optimize energy efficiency while ensuring thermal comfort in building energy management systems.

Effects of green roofs and vertical greenery systems on building thermal comfort in dry climates: an experimental study

Effects of green roofs and vertical greenery systems on building thermal comfort in dry climates: an experimental study

Investigation of Thermal Comfort in the Intelligent Building in Winter Conditions

The paper analyses thermal sensations, preferences and acceptability as well as humidity sensations of students in the intelligent building "Energis" of the Kielce University of Technology (Poland). The tests were performed in 8 lecture rooms, during which the volunteers filled in the anonymous questionnaires (with 3 to 7 possible answers for each question) and – simultaneously – physical air parameters were measured with Testo 400 microclimate meter. The study aimed to determine if the intelligent building provides proper indoor environment conditions during the heating season and to assess the accuracy of the standard methodology for thermal comfort determination. Experimental analysis of thermal and humidity sensations revealed that a share of the respondents critically assessed the indoor environment: 17% regarding temperature and 30% regarding humidity. Moreover, the standard methodology for thermal comfort calculations proved overwhelmingly inaccurate compared to the experimental data (with the results for 6 rooms being beyond the 50% error range). Since smart buildings are still not very common in Central Europe, the experimental data obtained in the study can be valuable both from the scientific but also practical point of view – providing useful data for building engineers and designers.

Urban Building Thermal Comfort Research Based on ArcGIS and Building Parameters: Analyzing and Improving Measures

Urban Building Thermal Comfort Research Based on ArcGIS and Building Parameters: Analyzing and Improving Measures