Thermal Comfort Research Articles

Analyzing Passive Design Retrofits using Pareto Front Optimization to Reduce Operational Carbon in Commercial Laboratory Spaces

Buildings are one of the leading sources of carbon emissions in the world. Most of the carbon emissions are released during the operation phase of the building. It is essential for buildings to provide thermal and visual comfort for the users. In the case of existing buildings, it is necessary to offer retrofit solutions so that the operational carbon emissions can be reduced without compromising on the other essential factors. In this study a Multi-Objective Optimization (MOO) of passive design strategies was conducted for a commercial laboratory in India situated in a moderate climate zone. The design variables considered for the study are wall and roof insulation, glazing material, window-wall ratio (WWR), depth of shading device and the number of shading devices used. The objective functions are: 1. reduced energy use intensity and operational carbon emissions, 2. increased thermal comfort hours and 3. increased daylight autonomy. Rhinoceros and grasshopper software along with Ladybug and Honeybee plug-ins were used for the study which resulted in 1296 iterations. MOO technique namely Pareto front optimization was used to optimize the objective functions. Out of 1296 solutions (excluding base case), 72 solutions were non-dominated. Two methods are described in the study to identify the recommendations for retrofit. The first method describes a Heuristic method of selection using Design Explorer recommending 5 good solutions. In the second method a factor is evolved to identify the 5 best solutions in sequential order. The overall study recommends the use of EPS insulation for the RCC roof, WWR of 20% on all sides, 3 horizontal shading devices of depth 0.75 m for all window openings. When compared with the base case scenario, this solution minimizes the EUI by 3.7%, maximizes average TCH by 106.6% and maximizes average DA by 66.9%. The overall operational carbon emissions are reduced by 7095.6 kgCO2.

Evaluation of physical risk factors by fuzzy failure mode and effects analysis: an apparel mill example

This study investigates the evaluation of risks faced by employees in a selected large-scale apparel mill using a risk assessment method with a fuzzy logic approach. The study found that risk assessment in the apparel industry is more accurate and reliable when using a fuzzy logic approach. Measurements were taken in three different time periods for noise, vibration, thermal comfort and lighting, which are physical risk factors. To evaluate the identified failure modes, the Failure Mode and Effects Analysis (FMEA) method was first applied. Then, for the same failure modes, the fuzzy FMEA method was applied using Fuzzy Logic Designer, an add-on to MATLAB. The study concludes that the fuzzy FMEA method can be a more useful method for risk assessment in the apparel industry.

Determination of the optimal dose and dosing strategy for effective L-menthol oral rinsing during exercise in hot environments.

This multi-study programme investigated the optimal concentration of L-menthol delivered as an oral mouth rinse to modulate thermo-behaviour during exercise in a hot environment (35°C). In study 1, 38 participants completed a survey to establish an effective and tolerable range of L-menthol concentration. 31 participants completed an RPE-protocol examining 1. the dose-response effect of L-menthol mouth rinse on exercise performance (n = 16) and 2. the temporal effectiveness of administering L-menthol in an incremental and decremental dosing pattern (n = 15). Power output, heart rate, body core temperature and thermal sensation were reported throughout. The optimal menthol concentration for peak power was between 0.01 and 0.1% (~ 6% increase, P < 0.05) and 0.5% (~ 9% increase, P < 0.05) with respect to control. Work completed was increased at 0.01% (~ 5%, P < 0.05), at 0.1% (~ 3%, P < 0.05) and had a detrimental effect at 0.5% (- 10% decrease, P < 0.05). There were no differences between an ascending dose protocol (0.01 to 0.5%), descending dose protocol (0.5-0.01%) or a constant 0.01% dose protocol. There were no reported differences in body core temperature or heart rate across trials (P > 0.05). The optimal dose of L-menthol when delivered via oral rinsing is between 0.01 and 0.1%. At lower concentrations, L-menthol appears to be less effective and at higher concentrations (> 0.5%) L-menthol appears to elicit greater irritation and may not positively modulate thermo-behaviour during exercise in a hot environment.

Cold Coastal City Neighborhood Morphology Design Method Based on Multi-Objective Optimization Simulation Analysis

In the context of global warming and the frequent occurrence of extreme weather, coastal cities are more susceptible to the heat island effect and localized microclimate problems due to the significant influence of the oceanic climate. This study proposes a computer-driven simulation optimization method based on a multi-objective optimization algorithm, combined with tools such as Grasshopper, Ladybug, Honeybee and Wallacei, to provide scientific optimization decision intervals for morphology control and evaluation factors at the initial stage of coastal city block design. The effectiveness of this optimization strategy is verified through empirical research on typical coastal neighborhoods in Dalian. The results show that the strategy derived from the multi-objective optimization-based evaluation significantly improves the wind environment and thermal comfort of Dalian neighborhoods in winter and summer: the optimization reduced the average wind speed inside the block by 0.47 m/s and increased the UTCI by 0.48 °C in winter, and it increased the wind speed to 1.5 m/s and decreased the UTCI by 0.59 °C in summer. This study shows that the use of simulation assessment and multi-objective optimization technology to adjust the block form of coastal cities can effectively improve the seasonal wind and heat environment and provide a scientific basis for the design and renewal of coastal cities.

Improvement of thermal environment in the outdoor atrium by employing the spray system

Outdoor atriums have recently been applied with increasing frequency for natural illumination, but they produce a harsh thermal environment easily in summer. Moreover, overheating of the outdoor atrium necessitates air-conditioning to moderate indoor thermal comfort. Simultaneously, the substantial heat emissions from air-conditioning outdoor units worsen the outdoor thermal environment, creating a vicious cycle. Traditional passive evaporative methods involving water and greenery, while capable of regulating the thermal environment, suffer from low evaporative efficiency and pose significant challenges. To improve thermal environment in outdoor atriums, the spray system was employed due to its high cooling efficiency, especially in open or semi-open spaces. In this study, a comparative experiment was conducted to evaluate the effectiveness of using a spray system for evaporative cooling in open outdoor spaces. Furthermore, employing high-efficiency evaporative cooling through spraying to disrupt the vicious cycle of indoor and outdoor thermal environments. The dual goals include regulating indoor and outdoor thermal conditions while also mitigating the local heat island effect. Temperature and humidity distribution within the atrium and adjacent hallways were monitored, along with the impact on air-conditioning operation consumption in neighboring offices. Results showed that the spray system significantly improved the thermal environment in the outdoor atrium, reducing the average and peak air temperatures by 0.94–2.83 °C and 2.92–5.21 °C, respectively. It also resulted in a drop in the average temperature by 0.56–1.62 °C and the peak temperature by 2.31–3.25 °C in adjacent hallways. This effectively eased the issue of overheating in these areas while raising the comfort level in adjacent office spaces. The predicted mean vote decreased from 1.46 to 0.87, indicating a significant improvement in thermal environment in neighboring offices. Furthermore, the daily energy consumption was reduced by 10.6–12.4% in neighboring offices. This study provided the valuable guidance for improving thermal environments within outdoor atrium.

Optimizing passive energy savings in rural self-built houses: Integrating phase change materials across China's climate zones

The energy consumption of rural residential buildings in China is increasing, and the integration of phase change materials (PCMs) has emerged as an effective strategy to mitigate building energy use and carbon emissions. Given China's diverse climate zones and the varying construction forms of rural self-built houses (RSHs), the efficacy of PCM applications varies significantly across regions. This study presents a comprehensive investigation into passive energy savings using PCMs in RSHs across various climate zones. We investigate the energy saving potential and thermal comfort effects of installing PCMs with varying phase change temperatures and thicknesses at different laying positions in representative buildings from each climate zone. The results indicate that the optimal phase change temperatures in different regions closely align with the outdoor average temperatures during the application season. When the optimal phase change temperatures and appropriate thicknesses of PCM are applied, cost-effective energy savings are consistently achieved in building roofing across regions, with the most significant effects observed in the Severe Cold region, where the uncomfortable degree hours reduction rate (φUDH) exceeds 90 %.

Towards a simplified model for partially open windows - connecting acoustic and thermal comfort

Traditionally, the internal environmental quality (IEQ) aspects of acoustic and thermal comfort have been considered and designed separately. However, where occupants rely on opening or closing windows to achieve these dimensions, they are not independent in use. To consider both simultaneously, it is crucial to have a simple model of a partially open window that can predict both acoustic and thermal conditions internally. CIBSE TM59 defines the assessment method for adaptive thermal comfort. In the thermal model the ventilation performance of open windows can be described with an "Equivalent Area" (EA). We propose to use the EA to calculate the facade sound insulation based on a simple assessment according to Annex D of ISO 12354-3, i.e. as a facade element with an area of EA and zero sound insulation. This study presents field measurements of sound insulation according to ISO 16283-3 with road traffic sound sources, to evaluate the acoustic uncertainty of using the EA to calculate internal sound levels. Results show encouraging correlation between measurements of element-normalized level difference, Dn,e,w + Ctr and calculations based on the EA. This model is considered adequate for acoustic design purposes, and represents a significant simplification compared with previous proposals.

Impact sound insulation performance of floor coverings in a heavyweight reference floor with a floating floor

This study investigates the impact sound reduction performance of floor coverings used on the heavyweight standard floor of a floating floor structure in comparison with bare slab testbeds through on-site experiments. The laboratory performance evaluation of floor coverings designates only a bare slab between 100 mm and 160 mm as the heavyweight reference floor according to Annex C in ISO 10140-5. However, the recent expansion of over-floor heating systems has led to an increased need for understanding the impact sound reduction performance of floor coverings on floating floors, to enhance occupants' thermal comfort. In this study, it was measured the heavyweight and lightweight floor impact sound reduction levels of various floor covering test specimens in testbeds with different thicknesses of bare slabs and actual apartment houses with floating floors applied. The reduction rate for each frequency band was determined before and after installing floor coverings including single number quantity in accordance with ISO 717-2. Additionally, the impact of heavyweight reference floor conditions on quantifying the sound performance of floor coverings was discussed.

Effects of indoor thermal-acoustic interaction on comfort and facial expression

While thermal-acoustic interaction is considered that to have an effect on comfort perceptions, the interaction effects of these factors and their impacts on perceived comfort and facial expressions have not been thoroughly investigated. In this study, the interaction effects between temperature and sound pressure levels on thermal, acoustics, overall comfort and facial expressions of young adults in offices were examined. The results showed that: (1) thermal-acoustic interaction and sound pressure levels had a significantly effect on thermal comfort, acoustic comfort and overall comfort; thermal comfort and overall comfort were significantly affected by temperature. (2) thermal-acoustic interaction had a significantly effect on the valence of facial expressions over a period from 20 to 60 seconds. (3) comfort perceptions had significantly correlations with several facial expressions.

Parametric and optimization analyses of a dynamic trombe wall incorporating PCM to save heating energy under cold climate zones

The Trombe wall system incorporating a dynamic PCM layer (DTWPS) has been recognized as a viable envelope to reduce the energy demand for heating effectively. However, properly selecting PCMs in the DTWPS is complicated and much less studied. Therefore, parametric and optimization analyses of the PCM thermal properties of a DTWPS are carried out for heating energy saving under cold climate zones using a validated CFD model, multiple linear and nonlinear regression models, and the particle swarm optimization (PSO) algorithm. The results show nonlinear relationships between the four critical PCM thermal properties and the energy saving, time lag, and thermal comfort. Moreover, the optimal values of the melting point, latent heat, density, and thermal conductivity of the PCM are 26.4 °C, 200 kJ/kg, 2080 kg/m3, and 1.34 W/(m·K), respectively. Meanwhile, the energy saving for the test room equipped with the DTWPS with optimal thermal properties could reach 100 % compared to that for the traditional reference Trombe wall. With available PCMs, heating energy consumption can be saved by up to 90 % or more. Further, the DTWPS demonstrates a reduced PCM mass compared to other passive walls.

Feet-heating and Calf-heating have Opposing Effects on Glucose Tolerance and Heart Rate Variability: A Randomized, Controlled, Crossover Trial.

Heat exposure's effect on glucose tolerance depending on the amount of body exposure, likely relating to autonomic nervous system balance. We assessed how partial-body heat exposure at two different levels of the lower extremities would affect glucose tolerance and autonomic nervous system balance measured via heart rate variability. We hypothesized feet-heating would improve glucose tolerance without affecting heart rate variability while calf-heating would worsen glucose tolerance and decrease heart rate variability compared to a thermoneutral control condition. In a randomized, controlled, crossover trial, healthy participants' (N=31, 23(3)years, 45% male) glucose tolerance was measured in A)thermoneutral; B)feet-heating; and C)calf-heating conditions. Every 30 minutes for 2 hours, blood glucose, heart rate, heart rate variability, tympanic temperature, thermal comfort scores, and blood pressure were measured. There were significant interactions between condition and time for blood glucose (F(4.6,72.6)=2.6,p=.036), heart rate (F(3.4,54.5)=3.5,p=.017), heart rate variability (F(4.3,63.2)=7.5,p<.0001), tympanic temperature (F(8,268)=2.4,p=.014), and thermal comfort scores (F(8,248)=22.1,p<.0001). Calf-heating increased 90-minute glucose (+12(95%CI: 3 to 21)mg/dL,p=.013) and decreased heart rate variability throughout (mean decrease: 13-22%,p<.007), while feet-heating lowered 90-minute glucose (-7(95%CI:-16 to +1)mg/dL,p=.090) without affecting heart rate variability (p=.14-.99). Blood pressure and body temperature were similar between conditions, but heart rate and thermal comfort scores increased with heating. Calf-heating worsens, while feet-heating may improve, glucose tolerance. Changes in heart rate variability coincide with changes in glucose tolerance despite unchanged body temperature. Whether heart rate variability can be used to monitor autonomic nervous system balance during heating to the effect on acute glycemic indices should be further explored.

Using geothermal energy in enhancing all-air HVAC system performance - Case study, thermal analysis and economic insights

The background is the same for addressing the twin challenges of attaining thermal comfort and concurrently reducing energy use and CO2 emissions. As a safeguard against worsening contamination, combining geothermal energy with an All-Air Heating, Ventilating, and Air Conditioning system (HVAC) with 100 % fresh air intake is also crucial in the context of the lessons learned from the COVID-19 pandemic. As a result, this study suggests using geothermal energy as a backup source to run a typical All-Air centralized HVAC system. The resulting system is referred to as a combined system from now on, and its primary goals are to lower the amount of operating energy needed while being environmentally and financially sound. In this context, the creative way of combining the suggested geothermal duct with the All-Air HVAC system possesses various insights, as demonstrated by the thorough thermal analysis and related design. Strong conclusions were derived from a thorough case study focused on Lebanon: adding 100 % fresh air intake leads to an astounding yearly energy savings of 67 %, whereas configurations with 10 % and 30 % fresh air produced energy savings of 52 % and 36 %, respectively. In the study, a geothermal multi-duct system was also suggested and looked at. The research revealed that the 311-m length of the single geothermal duct connected to a pressure of 7000 Pa was reduced to 210 m and the pressure drop was lowered to 140 Pa when a geothermal multi-duct system was employed. Furthermore, as the computed payback period makes clear, the integrated system presents an appealing chance to drastically cut resource usage during energy consumption, lower CO2 emissions, and provide 100 % fresh air circulation.

Enhancing autumn greenway walking experience: Exploring the combined effects of noise and thermal environment.

The evaluation of outdoor green spaces is influenced by diverse sensory perceptions. Traffic noise and thermal conditions significantly impact greenway-walking satisfaction; their optimization is vital for improving user experience and encouraging outdoor engagement. The study examines a typical Beijing greenway during autumn, focusing on strategies to enhance the walking experience under the combined effects of noise and thermal environments through mobile measurements and surveys. The results show that: 1) The interplay between noise and thermal factors varies depending on the walking state. Upon arrival, an increase in noise significantly worsens thermal comfort; higher sound levels intensify warm thermal sensations, though this effect is not consciously perceived. Upon departure, the effect of noise on thermal perception is not obvious. In both walking states, thermal sensation significantly affects subjective noise perception, yet the trends of influence differ. Subjective noise loudness increases as thermal comfort worsens, showing significant correlation only upon departure. 2) During autumn greenway walks, acoustic factors exert a greater impact on Overall Environmental Satisfaction (OES), with subjective noise loudness being more influential than noise level, followed by air temperature (Ta). Greater noise decreases OES, while OES increases initially with Ta and then decreases. The integrated effects of noise-thermal factors on OES show significant changes. 3) To enhance the autumn greenway-walking experience, the advised parameters are A-weighted Sound Level (ASL) ≤ 59.12 dBA and 15.17°C ≤ Ta ≤ 18.75°C. Finally, three design strategies are proposed: reducing subjective noise loudness, differentiating design based on walking status and balancing acoustic-thermal perceptual preferences.

Research on The local clothing thermal insulation prediction model with different dress state of indoor occupants

In a dynamic and non-uniform thermal environment, adjusting personal dress states is an effective method for achieving thermal comfort. During this process, clothing thermal insulation, as a key parameter in human thermoregulation models, is not uniformly distributed across the body. However, current thermal comfort standards do not provide a direct method for obtaining local clothing thermal insulation. Based on field surveys, this study summarized typical year-round clothing ensembles and common dress states, and tested the local thermal insulation of 40 clothing ensembles and 60 individual garments using a thermal manikin. Subsequently, a prediction model for the local thermal insulation of clothing ensembles was developed based on the overall thermal insulation of individual garments. Meanwhile, it was found that changes in dress state significantly alter the thermal insulation of body parts such as the arms and chest. Simulations conducted using the JOS-3 and UCB models revealed that the lower the ambient temperature, the greater the impact of changes in local clothing thermal insulation on human skin temperature and thermal sensation. Finally, a correction model for different dress states was developed, and comparison with existing models showed the lower root mean square error (RMSE) between the predicted and measured values. This study provides a more accurate and convenient method for determining local thermal insulation, offering a data foundation for improving indoor environmental control and enhancing energy efficiency.

Impact of wearing indoor masks on occupant’s thermal comfort under different room temperature conditions in winter

Impact of wearing indoor masks on occupant’s thermal comfort under different room temperature conditions in winter

Assessing thermal comfort for the elderly in historical districts and proposing adaptive urban design strategies: A case study in Zhenjiang, China

Assessing thermal comfort for the elderly in historical districts and proposing adaptive urban design strategies: A case study in Zhenjiang, China

Optimizing educational environments: microclimate analysis and energy efficiency through courtyard orientation in UAE schools

Sustainable school design is becoming increasingly important worldwide, particularly in the UAE, where schools are significant energy consumers. This study explores the impact of courtyard orientation on microclimate and energy consumption in UAE schools, utilizing a standardized template applied across 70 existing schools. By employing advanced simulation tools, ENVI-met and IES-ve software, the research provides a comprehensive analysis of air temperature and energy use related to different courtyard orientations, specifically on key dates of September 21st and March 21st, representing seasonal variations. The results indicate that North-facing courtyards consistently provide cooler microclimates compared to other orientations. Specifically, North-facing courtyards showed temperature reductions of 1.31°C in September and 1.9°C in March compared to the least favorable orientations. This orientation recorded the lowest average mass temperatures of 29.36°C in September and 25.13°C in March, surpassing the West-facing orientation by 0.39°C and 0.45°C, respectively. The primary factor for this improvement is the reduced solar radiation exposure on East-West aligned courtyards, which significantly lowers the heat gain. Additionally, the study assessed Physiologically Equivalent Temperature (PET) readings and cooling demands, both of which were found to be lower in North-facing courtyards. Cooling load reductions varied between 1% and 4%, depending on the day, further emphasizing the efficiency of this orientation. These findings suggest that strategic courtyard orientation is a critical design consideration for enhancing thermal comfort and energy efficiency in school buildings. The implications of this research are significant for sustainable design and construction practices. By highlighting the benefits of optimal courtyard orientation, this study offers practical solutions for reducing energy consumption and improving the indoor and outdoor thermal environments of schools. These insights contribute to the broader goal of developing greener, more sustainable educational facilities, particularly in hot climates like the UAE. This research not only informs architects and urban planners but also supports policymakers in implementing effective sustainability strategies in the educational sector.

Optimization of ventilation efficiency in tunnel-type underground spaces using response surface methodology: a case study of Yunlong Mountain civil defense in Xuzhou

Civil defense projects, designed as wartime underground spaces, often lack effective natural ventilation and have considerable depth, which complicates their use as public spaces in peacetime. However, the application of passive ventilation technologies can create effective airflow channels within these structures, significantly enhancing ventilation efficiency and thus improving the overall thermal comfort level. For this study, air age, along with average wind speed, temperature, and relative humidity as stipulated by the “Requirements for Environmental Sanitation of Civil Air Defense Works during Peacetime Use” (GBT 17216-2012), were selected as evaluation metrics. This paper compares the ventilation effectiveness between single ventilation shafts and multiple ventilation shafts under positive and negative pressure conditions in underground civil defense structures. The results indicate that negative pressure ventilation in multiple shaft configurations performs optimally across various ventilation approaches. Subsequently, the Response Surface Methodology (RSM) was utilized to further optimize the positioning of multiple ventilation shafts. The study examined the impact of three ventilation shaft locations on average wind speed, temperature, relative humidity, and air age, leading to an optimized design. Specifically, the optimal positions are 54.76 m for Shaft A, 51.45 m for Shaft B, and 79.85 m for Shaft C, achieving an average wind speed of 0.222 m/s, a temperature of 26 °C, a relative humidity reduction to 85.47%, and an average air age of 10.57 s. This research provides practical insights for the optimization of ventilation in underground civil defense facilities.

Investigation of thermal comfort and preferred temperatures among rural elderly in Weihai, China: Considering metabolic rate effects

As the population ages, the thermal environment indoors for the elderly has garnered extensive attention. However, current research on thermal comfort for the elderly is not comprehensive, particularly for rural elderly individuals who experience unique thermal perceptions and adaptation behaviors due to physical changes. Moreover, metabolic rates, which are often overlooked in thermal comfort studies for the elderly, play a crucial role. A year-long survey of thermal comfort was conducted in the rural areas of Weihai, a coastal city in China's cold region, collecting 203 questionnaires. Three different values of metabolic rates (recommended values, estimated values, and values calculated using Basal Metabolic Rate and Physical Activity Ratio) were analyzed. The results demonstrate that the Basal Metabolic Rate and Physical Activity Ratio method provides predictions of thermal sensation that more closely align with actual thermal sensations. The adaptive coefficient of the aPMV model was found to be −0.38 in colder environments and 0.272 in warmer ones. Additionally, using PMV regression, TSV regression, and Griffiths' method, we calculated the local elderly's comfort temperatures to be 18.9 °C (15.43–22.57 °C), 19.3 °C (15.16–22.75 °C), and 21.63 °C (21.34–23.49 °C) respectively. This study introduces a straightforward method for calculating metabolic rates in elderly individuals, offering new insights for research on thermal comfort in the elderly and expanding the database for thermal comfort studies. It lays a foundation for future design and standardization of housing for rural elderly populations.

The Impact of Green Building Design on Indoor Air Quality and Occupant Experience

This study examines the impact of green building design on indoor air quality (IAQ) and occupant experience, using Heritage Place in Ikoyi, Lagos, as a case study. Green buildings are known for incorporating sustainable practices such as the use of eco-friendly materials, advanced ventilation systems, and biophilic design elements, all aimed at enhancing environmental sustainability and occupant well-being. A descriptive survey methodology was employed, with data gathered through a questionnaire administered to 50 occupants of the building to assess their perceptions of IAQ, health, comfort, and overall satisfaction. The findings indicate that the majority of respondents reported high levels of satisfaction with IAQ, attributing improvements in their health, productivity, and comfort to the building’s green design features. Specifically, low-emission materials and enhanced ventilation systems were highly praised for reducing pollutants and maintaining a healthy indoor environment. However, a few respondents expressed concerns about inconsistent thermal comfort in certain areas. These results underscore the importance of sustainable design in creating healthier, more productive indoor environments. Recommendations for future green building projects include fine-tuning HVAC systems to improve thermal comfort and enhancing occupant education on the benefits of sustainable features.