Comfort Range Research Articles

Performance evaluation of semitransparent PV window systems employing periodic thermal model

A conventional window system can be replaced by a semitransparent PV window system, which generates electrical energy, provides natural daylighting, and improves the building's overall energy efficiency. The present study evaluates the performance of three different types of PV window systems, namely, STPV (Semitransparent Photovoltaic), SAG (Semitransparent-photovoltaic-Airgap-Glass), and VSAG (Ventilated Semitransparent-photovoltaic-Airgap-Glass) operating in heating and cooling mode, for the climatic conditions of Calgary, Canada. Periodic mathematical thermal models based on the energy balance equations of the window systems are developed to evaluate the systems' performance under the shading and non-shading effects of a curtain. The results indicate that the VSAG window system can be operated in heating mode to increase the room air temperature and in cooling mode to decrease the room temperature. Additionally, the curtain's transmissivity, PV modules' packing factor, and airflow rates could be used as a controlling measure to keep the room temperature within a comfortable range in different climatic conditions. Reducing the transmissivity of the curtains by 20% lowers the room temperature by 2.5 °C while decreasing the packing factor by 10% increases the room temperature by 4.8 °C.

A fast-response preheating system coupled with supercapacitor and electric conductive phase change materials for lithium-ion battery energy storage system at low temperatures

The electrochemical performance of lithium batteries deteriorates seriously at low temperatures, resulting in a slower response speed of the energy storage system (ESS). In the ESS, supercapacitor (SC) can operate at −40 °C and reserve time for battery preheating. However, the current battery preheating strategy has a slow heating rate and cannot preheat batteries to a comfortable temperature range during the time reserved by SC. This study proposes a preheating system that combines the instantaneous high-power discharge of SC with the efficient electro-to-thermal conversion of ECPCM, which has a super-fast preheating rate and contributes to the fast response of ESS at low temperatures. Under extreme conditions of −40 °C, the preheating system can recover >85 % discharge capacity and voltage of the battery system in 2 min. By adjusting SC capacitance and ECPCM resistance, the preheating rate of the battery system can reach 69.5 °C/min, and the temperature difference is less than 5 °C. Moreover, the pulse current of SC can reduce the temperature difference inside the battery within 5 °C. The preheating system can also enable the battery system quickly enter super-charging mode, greatly reducing the charging time. The total charging time was reduced by 72 % when the battery pack was preheated to 20 °C. Nevertheless, based on the outcome of this study, this preheating strategy can effectively improve the low-temperature response speed of the ESS and meet the requirements of the microgrid.

Outdoor thermal perception in the semi-arid climate of Constantine, Algeria: A field survey during the post-COVID-19

The purpose of the paper was to assess pedestrians' thermal perception, in the semi-arid climate of Constantine, Algeria, with particular emphasis on the protocols implemented in public spaces during the post-COVID-19. Three outdoor public spaces were selected in August 2021 to conduct a field study involving 254 respondents, randomly assigned. The adopted approach combined objective and subjective assessment, as well as numerical simulations using ENVI-met. Accordingly, microclimate monitoring and a questionnaire survey were carried out simultaneously from 7 a.m. to 7 p.m. in each study site. A strong association was found between the combined microclimate parameters (objective variables) and thermal sensation of the surveyors with (R2 = 0.74). Besides, Kruskal-Wallis H test revealed that the subjective thermal sensation was significantly influenced (p-value <0.05) by thermal history and purpose of visit (subjective variables). Most interviewees preferred ‘move to shade’ measure as a remedial behavior to reduce their thermal discomfort. Further, a neutral temperature of 22.7 °C PET was obtained by a linear regression between the Mean Thermal Sensation Votes (MTSV) and Physiological Equivalent Temperature (PET), the comfort range was estimated between 18.6 °C ≤ PET≤ 26.8 °C during summer. Regarding the COVID-19 pandemic effects, the Chi-square test suggests that the frequency of pedestrian visits was statistically independent of the imposed pandemic measures. However, the planned activities were affected by social distancing and the use of face masks increases pedestrians' thermal discomfort. Overall, the study highlights the significance of environmental and non-environmental factors to improve outdoor thermal comfort, and ensure human well-being.

Adaptive thermal comfort in naturally ventilated hostels of warm and humid climatic region, Tiruchirappalli, India

• Comfort range for hostel building was found between 26.1 and 32.8 °C. • The desired temperature was found to be 27.8 °C, while neutral temperature was 29.5 °C. • The comfort limit extended by 2.8 °C if air velocity rises from 0.1 to 1.1 m/s. • Sweating Acceptability extended the thermal acceptability limit from 31.8 to 32.4 °C. • At 26.6 °C temperature about 50% of the fans were found switched on. Thermal comfort is an important factor in hostel buildings when the aim is to maximize the productivity of the students. Due to the extreme weather conditions, achieving thermal comfort in a hostel building in a hot and humid climate is even more difficult. Studies conducted in naturally ventilated hostel buildings in warm-humid climates involved the influence of outdoor air temperature only up to 34.4 °C and have been conducted in a specific season. In contrast, the Tiruchirappalli climate is characterized by a higher range of environmental variables. Therefore, to understand the thermal comfort conditions and usage of the environmental controls in naturally ventilated hostel buildings at the higher range of the environmental variables, a thermal comfort field study spread over one year was carried out at the National Institute of Technology, Tiruchirappalli, India, in twenty-seven hostel buildings. This study relies on field observation and thermal comfort responses from 2028 questionnaires collected from the students between September 2019 to August 2020. The analysis revealed a neutral temperature of 29.5 °C and a comfort range from 26.1 °C to 32.8 °C, indicating a wide range of thermal adaptation than suggested by the National Building Code of India and ASHRAE standard 55. The preferred temperature was 27.8 °C, indicating that students preferred a cooler environment. Acceptability with sweating conditions extended the upper limit of thermal acceptability from 31.8 °C to 32.4 °C. The use of a mosquito net can increase the probability of opening a window. Results indicated that overall behavioral adjustment could extend the comfort limits. The study results would be helpful to develop guidelines and designs for naturally ventilated hostel buildings in warm and humid climates that will contribute to reducing energy demand.

Thermal sensitivity and adaptive comfort in mixed-mode office buildings in humid subtropical climate

ABSTRACT This study evaluates thermal sensitivity, expectations, and adaptability in mixed-mode ventilated buildings by subjective and objective assessments. A field study of simultaneous measurements of physical environmental parameters and right-here-right-now surveys was conducted in three office buildings from summer to winter in humid subtropical climates. The study confirmed previous findings that thermal adaptability and preferences changes as the ventilation system switches between natural ventilation (NV) and air-conditioning (AC). Occupants in this study showed more sensitivity to temperature changes than previously reported by ASHRAE Standards, yet thermal sensitivity was the same under different modes of operation. The neutral temperature was 0.5 oC higher than the predicted neutral temperature by ASHRAE 55 under both modes of operation. Thermal expectations were 1.5 oC warmer than the neutral temperature estimated by ASHRAE 55 when the building was operated by AC, while thermal expectations were almost the same as predicted by ASHRAE 55 under NV mode. Thermal comfort range was 0.75 oC wider than those predicted by ASHRAE 55 under NV operation, and the same as ASHRAE 55 under AC operation. The findings of this research provide a better understanding of mixed-mode building operations and perspectives from occupants, important for building designers and building operation managers.

A Study on Modifying Campus Buildings to Improve Habitat Comfort—A Case Study of Tianjin University Campus

At present, the design and planning of teaching and living areas on university campuses are relatively straightforward but encounter problems, such as poor ventilation, low indoor air quality, and poor sound insulation. In this study, the teaching building and living area cluster at the Tianjin University campus were selected as the research objects. We verified the effectiveness of the simulation results before and after renovation through onsite testing. To improve ventilation, an atrium and patio were added to the teaching building, and the ventilation of the renovated building was studied. The indoor thermal environment intelligent control system regulates carbon dioxide (CO2) concentration and humidity in the teaching building and changes the thermal comfort of the teaching building. Limiting vehicle speeds near the teaching building and the living area cluster, using muffling materials and muffling equipment, and increasing greenery to reduce noise were factors we studied, considering whether they had a noise-reduction effect. It was found that the average number of air changes in the overall functional space of the first teaching building reaches 6.49 times/h, and the wind speed in the human activity region is below 1 m/s. When using a thermal environment intelligent control system, the indoor temperature throughout the year was within the thermal comfort range 81% of the time. The maximum noise around the teaching building during the daytime was 51.0 dB, the maximum noise at nighttime was 41.5 dB, and the maximum sound level on the facade of the living area cluster was 53 dB. The average noise-reduction rate was 22.63%, which exceeds the noise-reduction rate given in the above research literature.

Lateral Vibration Control Strategy of High-Speed Elevator Car Based on Sparrow Search Optimization Algorithm

Aiming at the problems of inefficient mitigation of the lateral vibration of high-speed elevator cars, which results in low riding comfort, this paper introduces the electromagnetic active rolling guide shoes and incorporates the sky-hook damping control strategy into the high-speed elevator structure. On this basis, it adopts an optimization algorithm based on Sparrow Search Algorithm (SSA) to adjust the parameters of the lateral vibration controller, thereby reducing the amplitude of the lateral vibration and controlling it within the human comfort range. Specifically, this paper first incorporates electromagnetic active rolling guide shoes into the vibration reduction device of the high-speed elevator car. Based on the motion characteristics of lateral vibration, a mathematical model is established in which the sky-hook damping control strategy is introduced. Then, a simulation model is built, and the damping parameters of the controller are optimized using the SSA, resulting in effective control of the lateral vibration amplitude of the high-speed elevator car. Simulations demonstrate that the lateral vibration control model of the high-speed elevator car, optimized by SSA, achieves lower amplitudes within the frequency range of 1–2 Hz compared to the results obtained by the Genetic Algorithm (GA), demonstrating the effectiveness of SSA in optimizing the damping parameters of the car controller. Finally, the simulation results are compared with the measured data, and the research findings indicate that the proposed method for lateral vibration control of the car can effectively suppress the lateral vibration amplitude.

Biomechanical stress distribution of medical inelastic fabrics with different porosity structures

Clothing fit and pressure comfort play important role in clothing comfort, especially in medical body sculpting clothing (MBSC). In the present study, different body movements (forward bending, side bending, and twisting) were adopted to simulate and investigate the biomechanical stress distribution of the human body with three kinds of porosity inelastic MBSCs through the finite element analysis method. The elastic modulus of the investigated MBSCs was also measured by means of tensile testing. Analytical results showed that in the compression region during body movements, the investigated inelastic MBSCs endured less compression stress, and most of the stress was transmitted to the human body. Moreover, the stresses on the body surface were decreased with the porosity increasing. However, most of the von Mises stresses on the human body were in the desired pressure comfort range. Therefore, these results could provide potential information in the modification of MBSC for medical applications.

Examination of hydrodynamic behavior of wind deflectors in the normal inner temperature with the point of more efficiency (Case study: Bwhsa Köppen climate classification of Kashan City)

One of the ways to achieve a building with higher energy efficiency and an efficient system is to use local architectural experiences. In the meantime, a wind deflector is one of the elements used in the past to create comfort. In the Bwhsa Köppen climate classification of Kashan City, they used to move and cool the air in the building. This study investigates the interior of these settlements in this climate to aim to reach greater efficiency of this element by CFD software, Energy Plus, and Open Studio with a descriptive-analytical method and then analyzes the results. A comparison of the results of the analysis of wind speed in wind turbines and how the wind is oriented in the interior is shown. Due to the low thermal mass of the wind deflector walls compared to the room, the temperature fluctuation is always higher than in the room. The main factors in temperature drop are proportionality of dimensions-air inlet valve to the windshield, water temperature, measurements, and height of the windshield column. Finally, to reduce the room temperature further, the priority is to use a spray windshield over windshield wipers. Especially windshields with water spray in which most of the room has a temperature of 25 degrees Celsius and are in Kashan city’s thermal comfort range.

Effects of Variations in the Tragus Expansion Angle on Users’ Comfort for In-ear Wearables

Tragus expansion angle (TEA) is an angular variable that quantifies the degree of outward expansion of the tragus cartilage induced by in-ear wearables worn in the human ear. However, the TEA cannot be measured directly, and the mechanism that explains how expansion variations affect users’ comfort experience is not well understood. The purpose of this study was to establish a quantitative relationship between variations in the tragus expansion angle and users’ comfort experience. TEA was measured on 400 healthy participants and normalized using a measuring device (ATMC prototype) and Tragus Expansion Index (TEI). Our results show that the comfort range across variations in TEA was similar for both sexes, yet compared to females, males could tolerate larger variations both in TEA and TEI. A quantitative relationship was established using TEI values, (dis)comfort ratings and GaussAmp function, which can be employed for ergonomic design purposes.

A Novel Molecular PCM Wall with Inorganic Composite: Dynamic Thermal Analysis and Optimization in Charge-Discharge Cycles.

The combination of electric heating and thermal energy storage (TES) with phase change material (PCM) can achieve load shifting for air conditioning energy saving in building sectors. Their non-flammability, relatively good mechanical properties, and low cost make inorganic PCMs attractive in construction engineering. However, PCMs often show poor thermal conductivity, low heat transfer efficiency, leakage risk, etc., in applications. Moreover, the practical thermal performance of PCM-TES sometimes fails to meet demand variations during charge and discharge cycles. Therefore, in this study, a novel integrated electric PCM wall panel module is proposed with quick dynamic thermal response in space heating suitable for both retrofitting of existing buildings and new construction. Sodium-urea PCM composites are chosen as PCM wall components for energy storage. Based on the enthalpy-porosity method, a mathematical heat transfer model is established, and numerical simulation studies on the charge-discharge characteristics of the module are conducted using ANSYS software. Preliminary results show that the melting temperature decreases from 50 °C to approximately 30 °C with a 30% urea mixing ratio, approaching the desired indoor thermal comfort zone for space heating. With declining PCM layer thickness, the melting time drops, and released heat capacity rises during the charge process. For a 20 mm thick PCM layer, 150 W/m2 can maintain the average surface temperature within a comfort range for 12.1 h, about half the time of a 24 h charge-discharge cycling periodicity. Furthermore, placing the heating film in the unit center is preferable for improving overall heat efficiency and shortening the time to reach the thermal comfort temperature range. This work can provide guidance for practical thermal design optimization of building envelopes integrated with PCM for thermal insulation and energy storage.

Thermal Comfort Assessment in University Classrooms: A Discriminant Analysis for Categorizing Individuals According to Gender and Thermal Preferences

The concern with the well-being of users in buildings has become increasingly essential, covering aspects related to health, energy efficiency, and productivity. The thermal environment evaluation in buildings has become more frequent due to the time people spend inside them. In this context, this study aimed to analyze thermal comfort in classrooms at a Brazilian University. During the autumn, 50 measurements were performed, resulting in 519 valid responses. The results of the linear regression analysis revealed that the thermal comfort range for females was 20.39–22.19 °C, while for males it was 19.47–22.56 °C. Through discriminant analysis, participants were classified based on their thermal sensation vote (TSV), predicted mean vote (PMV), and thermal preference votes (PREF), achieving a success rate of 76.1% for females and 81.6% for males in forming the groups, which demonstrates the effectiveness of discriminant functions in predicting thermal comfort for both groups. These results highlight the importance of considering gender differences in the search for thermal comfort conditions and providing guidelines that promote the well-being of occupants and the conscious use of energy. This implies adjusting the thermal conditions according to the specific needs of males and females in classrooms, always seeking to provide a suitable environment for activities, and considering energy efficiency and users’ productivity.

Universal thermal climate index in the Arctic in an era of climate change: Alaska and Chukotka as a case study

The modern unambiguous climate change reveals in a rapid increase of air temperature, which is more distinctly expressed in the Arctic than in any other part of the world, affecting people health and well-being. The main objective of the current research is to explore the inter- and intra-annual changes in thermal stress for people in the Arctic, specifically for two parts of Beringia: Alaska, USA, and Chukotka, Russia, using climatology of the universal thermal climate index (UTCI). Data for 39 locations are taken from the ERA5-HEAT reanalysis for the period 1979–2020. Climatologically, the study area is divided into four subregions in Alaska: North, Interior, West and South, and two in Chukotka: Interior and Coast. The extreme coldest UTCI categories (1 and 2) are most common in coastal locations of northern Alaska and Chukotka, where strong winds exacerbate the low temperatures during winter. The results show that the frequency of category 1 (UTCI<−40°C) varies spatially from a quarter of all hours annually in Alaska North to almost zero in Alaska South. On the other hand, the warmest categories are rarely reached almost everywhere in Alaska and Chukotka, and even categories 7 and 8 (UTCI between +26 and +38°C) are found occasionally only at interior locations. Category 6 with no thermal stress (UTCI between +9 and+26°C) has frequencies up to 3% and 25% in Alaska North and Interior, respectively. The extremely cold thermal stress frequencies have substantially decreased over the 1979–2020 period, especially in Alaska North and Chukotka Coast. At the same time, the number of hours with UTCI in the comfortable category of thermal perception has increased depending on subregion, from 25 to 203 h/year. Overall, a decrease in the UTCI categories of extremely cold stress is coupled with an increase in the comfortable range in both Alaska and Chukotka. The salient conclusion is that, from the point of view of comfort and safety, global warming has a positive impact on the climatology of thermal stress in the Arctic, providing advantages for the development of tourism and recreation.

The underpinning factors affecting the classroom air quality, thermal comfort and ventilation in 30 classrooms of primary schools in London

The health and academic performance of children are significantly impacted by air quality in classrooms. However, there is a lack of understanding of the relationship between classroom air pollutants and contextual factors such as physical characteristics of the classroom, ventilation and occupancy. We monitored concentrations of particulate matter (PM), CO2 and thermal comfort (relative humidity and temperature) across five schools in London. Results were compared between occupied and unoccupied hours to assess the impact of occupants and their activities, different floor coverings and the locations of the classrooms. In-classroom CO2 concentrations varied between 500 and 1500 ppm during occupancy; average CO2 (955 ± 365 ppm) during occupancy was ∼150% higher than non-occupancy. Average PM10 (23 ± 15 μgm-3), PM2.5 (10 ± 4 μgm-3) and PM1 (6 ± 3 μg m-3) during the occupancy were 230, 125 and 120% higher than non-occupancy. Average RH (29 ± 6%) was below the 40–60% comfort range in all classrooms. Average temperature (24 ± 2 °C) was >23 °C in 60% of classrooms. Reduction in PM10 concentration (50%) by dual ventilation (mechanical + natural) was higher than for PM2.5 (40%) and PM1 (33%) compared with natural ventilation (door + window). PM10 was higher in classrooms with wooden (33 ± 19 μg m-3) and vinyl (25 ± 20 μgm-3) floors compared with carpet (17 ± 12 μgm-3). Air change rate (ACH) and CO2 did not vary appreciably between the different floor levels and types. PM2.5/PM10 was influenced by different occupancy periods; highest value (∼0.87) was during non-occupancy compared with occupancy (∼0.56). Classrooms located on the ground floor had PM2.5/PM10 > 0.5, indicating an outdoor PM2.5 ingress compared with those located on the first and third floors (<0.5). The large-volume (>300 m3) classroom showed ∼33% lower ACH compared with small-volume (100–200 m3). These findings provide guidance for taking appropriate measures to improve classroom air quality.

The performance of shallow GSHP in buildings for heating and cooling: A case study in Jordan

The versatility of heat pump technology in heating and cooling applications is attracting much attention. Thanks to its great efficiency and inexpensive capital and operating expenses, it has found widespread use. One major downside was a sharp decline in heat output and COP as outside temperatures fell. When calculating the COP of such devices, ambient temperature is a major factor. According to studies done in the past, working in a comfortable temperature range is much better than doing so in extreme heat or cold. The ambient conditions near the surface are more stable and less prone to fluctuations than the air temperature at the surface. In this study, we compare the efficiency of two different working fluids (R134a and R290) in an ideal vapor compression cycle when operating at subsurface (-2 m) ground temperature and at the temperature of home water wells in northern Jordan. The heating and cooling modes are the focus of this research. The proposed system is mathematically modeled, validated, and solved. The results show that the heat pump's efficiency improves by 10% to 11.2% during the colder months. Meanwhile, summertime improvements ranged from 9.8% to 27.4%. Last but not least, R290 refrigerant could replace R134a if the risk of ignition is considered.

Simulation and Machine Learning Investigation on Thermoregulation Performance of Phase Change Walls

The outdoor thermal environment can be regarded as a significant factor influencing indoor thermal conditions. The application of phase change materials (PCMs) to the building envelope has the potential to improve the heat storage performance of building walls and, therefore, effectively regulate the temperature variations of the inner surfaces of walls. COMSOL Multiphysics software was adopted firstly to perform the simulations on the thermoregulation performance of phase change wall; the time duration of the temperature at the internal side maintained within the thermal comfort range was used as a quantitative evaluation index of the thermoregulation effects. It was revealed from the simulation results that the time durations of thermal comfort were extended to 5021 s and 4102 s, respectively, when the brick walls were filled with two types of composite PCMs, namely eutectic hydrate (EHS, Na2CO3·10H2O and Na2HPO4·12H2O with the ratio of 4∶6)/5 wt.% BN and EHS/5 wt.% BN/7.5 wt.% expanded graphite (EG), under the conditions of 18 °C ambient temperature and 60 °C heating temperature at the charging stage. Both of them were longer than 3011 s, which corresponds to a pure brick wall. EHS/5 wt.% BN/7.5 wt.% EG exhibited better leakage prevention performance and, therefore, was a candidate for actual application, in comparison with EHS/5 wt.% BN. Then, a machine learning training process focused on the temperature control effects of phase change wall was carried out using a BP neural network, where the heating surface and ambient temperature were used as input variables and the time duration of indoor thermal comfort was the output variable. Finally, the learning deviation between the raw data and the results obtained from machine learning was within 5%, indicating that machine learning can accurately predict the temperature control effects of the phase change wall. The results of the simulations and machine learning can provide information and guidance for the advantages and potentials of PCMs of hydrate salts when being applied to the building envelope. In addition, the accurate prediction of machine learning demonstrated its application prospects to the research of phase change walls.

Experimental study and numerical simulation of a floor heating system in a three-dimensional model: Parametric study and improvement

In recent years, the installation of underfloor heating systems has increased considerably in many countries, due to their ability to be connected to a solar thermal collector in order to benefit from clean and renewable energy. This promising technology allows for reduced energy consumption, achieves a higher level of comfort, and ensures a more homogeneous temperature distribution than conventional heating systems. A huge loophole is detected in research works concerning the three-dimensional numerical modelling of the thermal behavior of underfloor heating by COMSOL Multiphysics software. The present study aims to reduce these knowledge gaps and to analyze the thermal behavior of the direct solar floor numerically and experimentally under the specific climatic conditions of Casablanca, Morocco. Visualize the thermal behavior of the underfloor heating system and the heating circuit as a 3D model using COMSOL Multiphysics software, based on the finite element method by investigating the influence of various design and operational parameters to select the best parameters that guarantee thermal comfort in the case of installing this heating system in traditional bathrooms.The results obtained by numerical simulation are then compared with those of the experimental measurements in order to verify the validity of the numerical model. The average deviation between the simulated and measured surface temperatures is approximately 1.04%, while the deviation in pipe temperature is around 3.13%, which shows a very good agreement between the numerical and experimental results. In addition, the results of the parametric study indicate that the key elements for enhancing the floor heating system are primarily a floor covered by tile with a minimum thickness of 5 mm, a pipe spacing of approximately 15 cm, a PER pipe diameter of 16/20 mm, and a thermal insulation layer with a thickness of 50 mm made of XPS or polystyrene. The incorporation of these improvements in the standard model ensures a surface temperature within the thermal comfort range of a less warm bathroom, approximately 34.13 °C, and a high heat flux emitted at the surface around 502.07 W compared to the standard model. In the literature, it was found that the comparison of architectural characteristics of direct solar floors receives minimal attention, with most studies only comparing systems in terms of thermal comfort or energy efficiency. In this study, the analysis and interpretation of the results obtained can be used to help engineers and designers select the type and dimensions of the best materials for heating floors installed in traditional bathrooms in Morocco.

Extreme Recreational Conditions in the Black Sea Resorts Associated with the North Atlantic Climate

The tourist and recreational conditions of the Mediterranean-Black Sea resorts are closely related to hydrometeorological anomalies, which in turn are largely associated with the North Atlantic climate. The aim of this paper was to study the change and variability of the bioclimatic indices and their extremes at the Black Sea resorts (on the example of Yalta, Southern coast of Crimea, and Sochi, Caucasian coast) associated with the North Atlantic Oscillation (NAO) and East Atlantic Oscillation (EAO). Using daily NCEP/NCAR (2.5° × 2.5°) and E-OBS (0.25° × 0.25°) reanalysis datasets, bioclimatic indices (wind cooling index, weight oxygen content, and equivalent-effective temperature) were calculated for January and July in 1950–2013/2018. The extreme index values were obtained using the 5th and 95th percentile relative thresholds. The results suggest that bioclimatic indices in Yalta are more sensitive to the global warming effect than those in Sochi, likely due to the geographical features. As a result, Yalta is becoming a year-round resort. It was shown for both resorts that negative EAO phase is significantly manifested in the increase of windy days in July versus the increase of windless days in the positive phase, and in the more frequent fresh and cold days in July (versus the opposite conditions in the positive phase only in Yalta). The NAO manifestations are mostly less pronounced than those of the EAO and are more significant in Sochi (mostly in January and in the negative NAO phase). Thus, it was shown that extreme values of bioclimatic indices occur at both resorts on the interannual scale depending on the NAO and EAO phases, but the conditions remain in the comfort range for now, even with the significant linear trends. The study can be expanded to other Mediterranean–Black Sea resorts for their sustainable development in a changing climate.

Evaluating thermal comfort and neutral temperature in residential apartments in hot and dry climate: A case study in Shiraz, Iran

Determination of thermal comfort, as one of the main goals of climate design, is of great importance due to its direct impact on human productivity and health, the interior space quality, and the energy consumption reduction, regarding the fact that most of the human activities take place in the house. Though providing crucial design information, determination and analysis of the thermal comfort range is a challenging issue due to variety of climatic, physiological, and cultural influencing factors, which in turn, necessitate field studies. Considering the critical need of determining thermal comfort range for each climate, this research aimed to describe field study of thermal comfort conducted in mid-rise residential apartments with open courtyards in hot and dry climate of Shiraz, Iran to provide neutral temperature, thermal comfort range, and the relationship between neutral temperature and indoor as well as outdoor temperature. The data and information needed, based on the experimental and field methods, were collected using the two main methods of questionnaire and measurement and the results were discussed with analytical and inferential description. In addition to a positive correlation between indoor air temperature and PMV as well as AMV, the findings of survey and regression analysis reveals a good relationship between neutral temperature and indoor temperature and also, between indoor comfort and outdoor conditions. Furthermore, a neutral temperature of 27.18 °C and the comfort band (23.2–30.8 °C) vindicated that respondents achieve comfort at a higher indoor air temperatures compared with the recommendations of international standards such as ISO7730. Moreover, the regression equation between the preferred and neutral temperature suggests that the neutral temperature can be used as a suitable criterion for predicting indoor temperature.

Thermal performance analysis of PCM solar wall under variable natural conditions: An experimental study

Low-carbon technologies are critical for mitigating climate change and achieving net-zero emission buildings. Phase change material (PCM) solar wall as a low-carbon technology is a passive heating/cooling system with the potential to cover a significant portion of building energy demand. To better understand the potential of PCM solar walls in different climates, further research into their performance is needed. This research is based on an experimental investigation of the performance of the Solar wall test cell in changing natural conditions for cold and warm seasons. A series of experiments were conducted in both seasons by recording the variation of exterior and interior temperature, as well as solar radiation. Statistical tools were used to analyze the influence of variations in external air temperature and solar radiation on the thermal characteristics of the solar wall in the cell. The results showed a significant difference between external and internal temperature variations for both seasons. Particularly, the wall had the potential during the heating season to maintain the temperature of the test cell above 20 °C for up to 7 h, while in the cooling season, it is observed that the wall keeps room temperature for about 17 h within the comfort range.