bluuebunny/crossref_metadata_2025 huggingface dataset:
Thermoelectric properties of X3N2O2 (X = Hf, Zr) MXene monolayers: a first-principles study
Authors: Yan Xinxin , Cao Wei , Li Haohuan
Published: June 2023

MXene monolayers have received increasing attention due to their unique properties, particularly their high conductivity, which shows great potential in thermoelectric materials.
Metal-free visible-induced C(sp2)–C(sp2) coupling of quinoxalin-2(H)-ones via oxidative cleavage of the C–N bond
Authors: Wu Mei , Lian Nancheng , Wu Cuimin , Wu Xinyao , Chen Houzheng , Lin Chen , Zhou Sunying , Ke Fang
Published: June 2023

A C(sp2)–C(sp2) reaction between aromatic hydrazines and quinoxalines has been developed through a photocatalytic system.
Continuous-flow transfer hydrogenation of benzonitrile using formate as a safe and sustainable source of hydrogen
Authors: Dempsey Seán D. , Ryan Ailbhe A. , Smyth Megan , Moody Thomas S. , Wharry Scott , Fahey Karen , Beale Andrew M. , Mediavilla Madrigal Sofia , Dingwall Paul , Rooney David W. , Knipe Peter C. , Muldoon Mark J. , Thompson Jillian M.
Published: June 2023

Demonstration of catalytic transfer hydrogenation of benzonitrile in flow using formate reducing agents.
Modulation of IL-17 backbone dynamics reduces receptor affinity and reveals a new inhibitory mechanism
Authors: Shaw Daniel J. , Waters Lorna C. , Strong Sarah L. , Schulze Monika-Sarah E. D. , Greetham Gregory M. , Towrie Mike , Parker Anthony W. , Prosser Christine E. , Henry Alistair J. , Lawson Alastair D. G. , Carr Mark. D. , Taylor Richard J. , Hunt Neil T. , Muskett Frederick W.
Published: June 2023

The varying dynamic nature of IL-17 dimers correlates to their affinity for IL-17 receptor A. An inhibitor of IL-17:receptor A binding was shown to rigidify IL-17A revealing an important new regulatory mechanism.
Palladium-catalyzed intramolecular asymmetric hydrocyclopropanylation of alkynes: synthesis of cyclopropane-fused γ-lactams
Authors: Lin Han-Ze , Qi Zhuang , Wu Qi-Min , Jiang Yong-Yu , Peng Jin-Bao
Published: June 2023

A palladium-catalyzed intramolecular asymmetric hydrocyclopropanylation of alkynes via C(sp3)–H activation has been developed for the synthesis of cyclopropane-fused γ-lactams.
Structure engineering of MoO3 breaks the scaling relationship and achieves high electrocatalytic oxygen evolution activity in acidic conditions
Authors: Wang Shuhua , Ren Zebin , Yu Shiqiang , Huang Baibiao , Dai Ying , Wei Wei
Published: June 2023

Alkali-metal modification and transition-metal doping are effective strategies to dislodge the inertia of MoO3 and obtain greatly reduced OER overpotentials.
Introduction to photofunctional materials and transformations
Authors: Wu Li-Zhu
Published: June 2023

Guest Editor Li-Zhu Wu introduces this cross-journal themed collection on photofunctional materials and transformations.
Biocompatible and bioactive hydrogels of recombinant fusion elastin with low transition temperature for improved healing of UV-irradiated skin
Authors: Li Jianan , Huang Wenjie , He Huixia , Shi Shuangni , Sun Xiuxia , Xiao Jianxi
Published: June 2023

Prolonged exposure to UV radiation can cause severe photodamage to the skin, leading to abnormal fragmentation of elastin fibers.
Combination of MRO SHARAD and deep-learning-based DTM to search for subsurface features in Oxia Planum, Mars
Authors: Xiong Siting , Muller Jan-Peter , Tao Yu , Ding Chunyu , Zhang Bochen , Li Qingquan
Published: June 2023

Context. Oxia Planum is a mid-latitude region on Mars that attracts a great amount of interest worldwide. An orbiting radar provides an effective way to probe the Martian subsurface and detect buried layers or geomorphological features. The Shallow radar orbital radar system on board the NASA Mars reconnaissance orbiter transmits pulsed signals towards the nadir and receives returned echoes from dielectric boundaries. However, radar clutter can be induced by a higher topography of the off-nadir region than that at the nadir, which is then manifested as subsurface reflectors in the radar image.

Aims. This study combines radar observations, terrain models, and surface images to investigate the subsurface features of the ExoMars landing site in Oxia Planum.

Methods. Possible subsurface features are observed in radargrams. Radar clutter is simulated using the terrain models, and these are then compared to radar observations to exclude clutter and identify possible subsurface return echoes. Finally, the dielectric constant is estimated with measurements in both radargrams and surface imagery.

Results. The resolution and quality of the terrain models greatly influence the clutter simulations. Higher resolution can produce finer cluttergrams, which assists in identifying possible subsurface features. One possible subsurface layering sequence is identified in one radargram.

Conclusions. A combination of radar observations, terrain models, and surface images reveals the dielectric constant of the surface deposit in Oxia Planum to be 4.9–8.8, indicating that the surface-covering material is made up of clay-bearing units in this region.
Deuterium fractionation across the infrared-dark cloud G034.77−00.55 interacting with the supernova remnant W44
Authors: Cosentino G. , Tan J. C. , Jiménez-Serra I. , Fontani F. , Caselli P. , Henshaw J. D. , Barnes A. T. , Law C.-Y. , Viti S. , Fedriani R. , Hsu C.-J. , Gorai P. , Zeng S.
Published: June 2023

Context. Supernova remnants (SNRs) may regulate star formation in galaxies. For example, SNR-driven shocks may form new molecular gas or compress pre-existing clouds and trigger the formation of new stars.

Aims. To test this scenario, we measured the deuteration of N2H+, DfracN2H+ – a well-studied tracer of pre-stellar cores – across the infrared-dark cloud (IRDC) G034.77-00.55, which is known to be experiencing a shock interaction with the SNR W44.

Methods. We use N2H+ and N2D+J = 1−0 single pointing observations obtained with the 30m antenna at the Instituto de Radioas-tronomia Millimetrica to infer DfracN2H+ towards five positions across the cloud, namely a massive core, different regions across the shock front, a dense clump, an+d ambient gas.

Results. We find DfracN2H+ in the range 0.03−0.1, which is several orders of magnitude larger than the cosmic D/H ratio (~10−5). The DfracN2H+ across the shock front is enhanced by more than a factor of 2 (DfracN2H+ ~ 0.05 - 0.07) with respect to the ambient gas (≤0.03) and simila+r to that measured generally in pre-stellar cores. Indeed, in the massive core and dense clump regions of this IRDC we measure DfracN2H+ ~ 0.01.

Conclusions. We find enhanced deuteration of N2H+ across the region of the shock, that is, at a level that is enhanced with respect to regions of unperturbed gas. It is possible that this has been induced by shock compression, which would then be indirect evidence that the shock is triggering conditions for future star formation. However, since unperturbed dense regions also show elevated levels of deuteration, further, higher-resolution studies are needed to better understand the structure and kinematics of the deuterated material in the shock region; for example, to decipher whether it is still in a relatively diffuse form or is already organised in a population of low-mass pre-stellar cores.
An Aisle Displacement Ventilation System for Twin-Aisle Commercial Airliner Cabin
Authors: Wang Feng , Chen Fan , Zhang Tengfei (Tim)
Published: June 2023

The environmental control system in most commercial airliner cabins supplies air from shoulder and ceiling level and exhausts air at floor level on both sides of the cabin walls. The ventilation system mixes air in the cabins to create a relative uniform air temperature distribution which is great for passengers’ thermal comfort. However, the mixing ventilation also enhances airborne contaminant transfer. Many displacement ventilation methods have been proposed to use in aircraft cabins, but the disadvantages of the ventilation approach are usually creating draft on the passengers’ ankles and high air temperature stratification between passengers’ heads and feet. This investigation developed an aisle displacement ventilation (ADV) system which can reduce air temperature stratification effectively without occupying the legroom space under the seats, so it is good for passengers and crew members’ comfort and friendly for luggage storage, in addition, it can also be easily installed in aircraft cabins. By installing the system in a five-row, twin-aisle cabin mockup, our study found that the ADV system can create a low air velocity distribution in the cabin and can maintain an acceptable air temperature stratification without draft. The system created an uprising airflow which can effectively remove airborne contaminant which was generated from index passengers’ respiratory activities. The experimental data were used to validate a computational-fluid-dynamics (CFD) program. The validated CFD program was used to compare the ADV with under-seat displacement ventilation (USDV) and underfloor air distribution (UFAD) system along the aisles. The comparison results show that the ADV had obvious better thermal comfort than the other two systems, and the cabin air quality of the three ventilation systems was similar, all far better than the “perfectly-mixed” ventilated condition.
Adaptive thermal comfort assessment of a naturally ventilated log house during summer under climate change impacts
Authors: Košir Mitja , Možina Matic , Kumar Singh Manoj , Pajek Luka
Published: June 2023

The study deals with a three-storey log house located in the suburbs of Ljubljana, Slovenia (temperate climate). Firstly, the calibrated thermal model of the log house was defined. The calibrated model had an hourly NMBE between −2.12 % and 1.84 % and a CV(RMSE) between 3.16 % and 3.57 %. Then, the adaptive thermal comfort during the warmer part of the year was assessed according to EN 16798-1 and future climate (SRES A2 scenario). Additionally, various building-related and organisational measures for overheating prevention were evaluated. It was found that the most effective measures to prevent overheating are the organisational measures of shading activation and night ventilation. It was demonstrated that the efficiency of night ventilation would even improve over time. Thus, at the end of the 21st century, discomfort hours could be reduced by 67 % compared to the baseline. In contrast, building-related measures have a significant effect only when combined with organisational measures. Overall, in 2071–2100 adaptive thermal comfort was improved most when the measure of increased thermal insulation was coupled with shading and night ventilation, resulting in 1053 discomfort hours less than the baseline case.
A novel approach based on EEG Entropy measurement for indoor human thermal comfort estimation
Authors: Mansi Silvia Angela , Pappalettera Chiara , Vecchio Fabrizio , Arnesano Marco
Published: June 2023

This paper presents a methodology for the application of electroencephalographic (EEG) Entropy measurements for indoor thermal comfort estimation. Wearables have been demonstrated to be capable of providing accurate physiological measurements to interpret individual thermal responses. Several studies demonstrated the correlation between the EEG Power Spectrum Density (PSD) variation and the subjects' responses exposed to different ambient temperatures. We present a complementary approach based on Approximate Entropy (ApEn) of EEG as a measure for the predictability of EEG series in describing the human thermal condition. We analysed the ApEn of EEG signals acquired from 24 subjects, exposed to three different temperatures (cold: 16°C; neutral: 25°C; warm: 33°C) in a controlled environment, by 4-channels wearable EEG sensors (256 Hz sampling frequency). Statistical analysis showed for both anterior frontal and temporoparietal sites significant differences between neutral, cold, and warm conditions, with a higher value of ApEn in the neutral one. In the anterior frontal area, there was a significative trend of ApEn with smaller values from the neutral to the warm condition, with the cold intermediate. The outcome opens the scenario up to innovative measurement systems, based on wearable EEG devices, for the application of personal comfort models to indoor environmental monitoring and control.
Mental stress and sleeplessness during the COVID-19 pandemic associated with socioeconomic status, preventive behaviors, and indoor environments
Authors: Murtyas Solli , Shaqour Ayas , Hagishima Aya
Published: June 2023

The outbreak of the SARS-CoV-2 virus forced people to work from home. This study aimed to examine the relationship between residents' mental stress, indoor environment quality (IEQ), preventive behaviors, and socioeconomic status (SES) in Indonesia by using a cross-sectional study with a questionnaire survey in Indonesia. A total of 1004 valid responses were obtained during the survey during the COVID-19 pandemic period (November-December 2021). Logistic regression and odds ratio (OR) was used to evaluate the association between the possibility of mental stress and sleeplessness relying on the classified group of income, education, and age. In addition, a structural equation model (SEM) was used to analyze the inter-relationship between these characteristics and their effects on mental stress and sleeplessness as a crisis variable. The results indicate that mental stress was more inclined among low-income households during the COVID-19 pandemic than middle-up and high-income groups, with OR = 0.48 and 0.50, respectively. Moreover, the SEM suggested that SES also had significant direct effects (p-value < 0.05) on preventive behaviors (ω = 0.105), IEQ (ω =0.102), and crisis (ω = −0.237). It evidenced that the higher socioeconomic levels could have less possibility of experiencing a crisis. The findings of this study could add to practical implications that support the researchers and public policy stakeholders in mitigating the long-term effect of COVID-19 in Indonesia related to mental health and indoor environments.
Contaminant removal effectiveness evaluation of ventilation, UR-UVGI, and air cleaner using CFD in negative pressure isolation ward
Authors: Kim Gihoon , Bang Jongil , Sung Minki
Published: June 2023

A negative pressure isolation ward (NPIW) is designed to create negative pressure to prevent the spread of airborne viruses. Therefore, it is necessary to increase the contaminant removal effect in the NPIW. To reduce indoor air contaminants, upper room-ultraviolet germicidal irradiation (UR-UVGI) and air cleaner are being used. Unlike the UR-UVGI, the air cleaner generates airflow. Therefore, the contaminant removal effect may differ according to the ventilation methods. This study is to compare ventilation, UR-UVGI, and air cleaner contaminant removal effects using CFD and Contaminant Removal Effectiveness (CRE) in the NPIW. As a result, the CRE of the ceiling and wall exhaust methods were different, and the CRE of the URUVGI and air cleaner cases were also different according to the two ventilation methods. Therefore, when applying UR-UVGI and air cleaner, it is necessary to consider the ventilation method.
Field investigation of lifestyle and indoor environment with COVID-19 in facilities for older adults in cold regions of Japan
Authors: Takeuchi Jinya
Published: June 2023

The emergence of COVID-19 clusters for older adults has been increasing recently in Japan. Facility staff control cross-ventilation with open windows as the primary measure against COVID-19 in facilities for older adults. In this study, the indoor thermal environment, lifestyle, ventilation method, and other in six facilities for older adults were investigated to understand how facility operation management has changed since the spread of COVID-19. As a result, the indoor air temperature was well-managed in all facilities during both seasons. However, the wet bulb globe temperature was measured above the warning level of 25 °C due to the influence of high indoor humidity in summer. The humidity in the facilities was always controlled under low-humidity conditions during winter. In the lifestyle investigation, many votes suggested that the staff found wearing masks uncomfortable. Most older adults were not wearing masks because it made them feel stuffy. Moreover, the staff opened windows for cross-ventilation without relying on objective judgment. Thus, if effective ventilation is not performed, the ventilation efficiency in the facility deteriorates and raises further infection risks. Therefore, staff in facilities should be maintained appropriate indoor carbon dioxide concentrations by ventilation during the COVID-19 catastrophe.
Effects of Droplet Generation by Respiration and Vocalization on Infection Risk
Authors: Kim Jeongil , Kurabuchi Takashi , Furusawa Arisu , Taguchi Haruki , Ri Hike , Lee Sihwan
Published: June 2023

Due to the COVID-19 pandemic, research on the quantitative evaluation of the risk of infection has become necessary. Because airborne transmission occurs by the inhalation of droplets from infected people, understanding the mechanism of droplet generation is important. In this study, the size distribution of droplets produced by various expiratory activities was investigated, the results were compared with those of previous studies, and the applicability of the simple measurement method was confirmed. The experiment was performed using an optical particle counter and a device that could continuously ventilate the generated droplets in a clean room with a low background concentration. Among the variables in the equation for calculating the quanta emission rate to evaluate the risk of infection, the droplet concentration and inhalation rates that could be measured were determined, and the relative risk of infection for each of the various expiratory activities was quantitatively evaluated. In addition to the cases identical to those in previous studies, conversations and vocalizations were conducted while wearing a mask. Particles smaller than 1 μm were analyzed based on the theory that viruses have a high proliferation rate and a high risk of infection. The concentration of droplets produced by the expiratory activity was dominated by particles with a number concentration of <1 μm; however, the mass concentration was only observed at a low rate. The risk of infection increased in proportion to the volume of voice, and was markedly higher in the case of loud voices. In addition, the risk of infection decreased when wearing a mask, and the extent of reduction varied depending on the method of wearing the mask.
Improved Thermal Performance of Combined Convection and Radiation Using Room Air Conditioner
Authors: Aoyama Kyohei , Kindaichi Sayaka , Nishina Daisaku , Nagaoka Hirokazu
Published: June 2023

This study aims to evaluate the indoor thermal environment within a detached residence in summer by applying combined convection and radiation air conditioning system using the refrigerant gas of room air conditioners (RACs). First, field measurements were performed in a detached residence at Hiroshima, Japan, in July and August 2021. Consequently, PMV values were generally maintained within the comfortable range during air-conditioning operation. The amount of heat generated by convection (via the RAC indoor unit) Qc and that by radiation (via the radiation panel) Qr were determined as 426 and 259 W, respectively, and the overall heat generated Qtotal was determined as 685 W. Applying the CFD model, thermal environment was compared varying the ratio between Qc and Qr with a constant Qtotal of 685 W. Results showed that the synergistic operation of a RAC and a radiant panel presented more comfortable PMV values than that of a single RAC application. Furthermore, the airflow from the RAC decreased with an increase in Qr ratio, and the chilled radiant panel provided a cooling effect around the dining area, where the airflow of the RAC was inadequate, thereby improving the thermal comfort.
An experimental study investigating differences in acclimatization capacity and thermal preference between university students and older workers
Authors: Caporale Alice , Zaniboni Luca , Wargocki Pawel , Mora Cristina
Published: June 2023

This experimental study aims to test thermal response and the ability to acclimatize during thermal discomfort conditions of different age groups. Experiments were conducted in late summer with thirteen participants, including university students and older workers, exposed in a climate chamber to a temperature increasing from 22°C to 28°C and decreasing from 22°C to 16°C, at a rate of 3.5K/h. Participants adjusted their clothing to stay thermally neutral at 22°C. After that, they were not allowed to change clothing during temperature ramps. Subjects rated their thermal comfort, preference, and acceptability during increasing and decreasing temperature ramps. Skin temperature was measured in two points to monitor the processes of vasoconstriction. Older workers showed higher vasoconstriction in both ramps due to more rapid and more significant cooling of extremities. However, older workers showed a higher tolerance for thermal discomfort conditions during the cold ramp, suggesting that they might physically suffer more from thermal discomfort but be less aware of it. During the hot ramp, older workers showed greater variability in psychological response, although comparable mean values suggest that thermal neutrality might remain similar with increasing age. For this reason, the percentage of dissatisfied among older workers could be different despite similar neutral temperatures. The results highlight the need to extend the study with comparable experiments to collect further data on older workers' acclimatization capacity and thermal preferences.
Development of the adaptive model for thermal comfort in office buildings of Aichi prefecture, Japan
Authors: Rijal Hom B. , Okamoto Shotaku , Khadka Supriya , Amano Katsunori , Saito Teruyuki , Imagawa Hikaru , Uno Tomoko , Genjo Kahori , Takata Hiroshi , Tsuzuki Kazuyo , Nakaya Takashi , Nishina Daisaku , Hasegawa Kenichi , Mori Taro
Published: June 2023

This study was undertaken to investigate seasonal adaptation to temperature in Japanese offices, with a view to suggesting an adaptive model for them. We measured temperatures in seven office buildings and conducted thermal comfort transverse surveys of occupants for over a year in the Aichi prefecture of Japan. We collected 1,228 samples. The occupants were found to be highly satisfied with the thermal environment in their offices. Even though the Japanese government recommends the indoor temperature of 28 °C for cooling and 20 °C for heating, we found that the comfort temperature was 2.8 °C lower in cooling mode and 4.3 °C higher in heating mode, in line with the actual indoor temperatures. The monthly variation in the temperature in the investigated offices was significantly lower than had been found in dwellings. An adaptive relationship can be derived to estimate the indoor comfort temperature from the prevailing outdoor temperature for similar office buildings.
A long-term monitoring study on the thermal comfort and durability of a straw bale Passivhaus cottage
Authors: Marincioni Valentina , Bradshaw Frances
Published: June 2023

The built environment sector accounts for 40% of the UK's total carbon footprint; bio-based construction materials can play an important role in reducing the whole-life carbon of a new build. Straw bale construction is one of the most promising bio-based methods of construction, due to its availability and material properties. Among the declared benefits of straw bale construction are the internal regulation of heat and moisture and the ability of the fabric to dry out. This paper presents a long-term monitoring study aimed at understanding the indoor temperature and moisture balance of a straw bale cottage built in the UK to a near Passivhaus level. The study lasted 6 years, monitoring the temperature and relative humidity of the indoor and outdoor environments, and in ten locations within the straw bale walls. The analysis has shown that the indoor environment achieved thermal comfort throughout the monitoring period, even when the building was used intermittently. Also, an analysis of surface temperatures and a mould growth risk analysis identified very limited mould growth risk within the building fabric. This paper shows the potential of straw bale low-energy construction in providing thermal comfort and a durable building fabric while minimising the whole-life carbon of buildings.
Comparative Evaluation of Four RANS Turbulence Models for Aerosol Dispersion from a Cough
Authors: Owolabi Jibola , Hassan Khawaja , Aganovic Amar
Published: June 2023

The study of aerosol dispersion in indoor environments is essential to understanding and mitigating airborne virus transmission, such as SARS-CoV-2. Computational Fluid Dynamics (CFD) has emerged as a valuable tool for investigating aerosol dispersion, providing an alternative to costly experimental methods. In this study, we investigated the performance of four (4) Reynolds-averaged Navier-Stokes (RANS) turbulence models in predicting aerosol dispersion from a human body coughing in a small, ventilated indoor environment. We compared the Standard, RNG, Realizable k-ϵ models and the SST k- ω model using the same boundary conditions. We initially observed that the horizontal distance of the coughed aerosols after 10.2s dispersion time was substantially shorter with the standard k-ϵ turbulence compared to the other three turbulence models compared to the SST k-ω model, the RNG, and realizable k-ϵ models exhibit a high degree of similarity in their dispersion patterns. Specifically, we observed that the aerosols dispersed horizontally faster with the RNG and Realizable k-ϵ models. In conclusion, when compared to qualitative data from the literature, our observations exclude the standard k-ϵ turbulence. However, to select the most appropriate turbulence model for capturing the cough flow and aerosol dispersion dynamics, further detailed validation against both quantitative and qualitative data is needed.
Creating an adaptive model for office buildings in cold climate
Authors: Tanaka Chisato , Mori Taro , Rijal H.B. , Uno Tomoko , Genjyo Kahori , Nakaya Takeshi , Nishina Daisaku
Published: June 2023

Japan's goal of becoming carbon neutral by 2050 requires both efficient use of facilities and maintenance of comfort for office workers in office buildings. In this paper, we clarify comfort temperatures from adaptive model in an office building in Hokkaido, as well as examine the factors that influence a more comfortable office environment. In the thermal comfort declaration, “Neutral” was the most declared in the MX mode (ventilated environment regardless of heating/cooling use), and the office workers were satisfied with the thermal environment. The comfort temperature was around 25°C in both MX and HT modes (heated environment), and a positive correlation was observed between the comfort temperature and the moving average outdoor temperature in MX mode, which led us to propose an adaptive model. Although the outdoor temperature in this model was about 8 °C lower than in previous studies, the comfort temperature was within the same range. There was no correlation between the amount of clothing worn by workers and their perception of cold and heat, but there was a positive correlation with the amount of activity.
The use of cluster analysis to assess thermal comfort in university classrooms
Authors: Mendes da Luz Inaiele , Lourenço Niza Iasmin , Broday Evandro Eduardo
Published: June 2023

Nowadays, providing health, well-being, productivity and energy efficiency to users inside buildings is essential. Applying these aspects aligned with sustainability becomes necessary to reduce the use of heating, ventilation, and air-conditioning (HVAC) systems. These systems are currently used to provide better thermal conditions to the occupants, who spend around 80% of their time indoors. The actual thermal conditions can be affected by several factors, such as the climatic type of the region, orientation, size, building type, and energy levels, among others. To assess thermal conditions inside buildings, several thermal comfort models have been developed over the years. However, the Predicted Mean Vote (PMV) created by Fanger is still the most common model to assess thermal comfort indoors. In this context, this research aimed to analyze thermal comfort conditions in university classrooms in Southern Brazil. By collecting the environmental and personal variables of thermal comfort and the mean thermal sensation of students through measurements and questionnaires, a total of 519 responses were obtained during the Brazilian autumn. A statistical cluster analysis was performed to classify individuals according to their sensations. Differences between genders were verified and changing indoor temperatures lower in winter would therefore save HVAC energy without impacting occupant comfort.
Development of a method for measuring and visualizing the concentration of aerosol particles using flame photometry
Authors: Mizutani Sasara
Published: June 2023

It has been pointed out that SARS-CoV-2, the cause of COVID-19, can cause droplet or droplet nucleus infection by aerosol particles. Therefore, there is a growing need for a method to investigate the behavior of aerosol particles. Currently, it is impossible to visualize aerosol particles and measure their concentration simultaneously. In this study, a method for measuring and visualizing the concentration of aerosol particles by flame photometry was developed. In this method, aerosol consisting of a sodium chloride solution is used as tracers for human-droplet and droplet nuclei, and the amount of sodium in the aerosol particles is determined by the flame color reaction of a burner. Experiments using the developed method showed that the aerosol can be visualized by the flame color reaction and showed the same trend as that of a particle counter, indicating that the amount of aerosol can be measured using this method. This study suggests that this method may be applied to evaluate the effectiveness of aerosol ventilation, propose appropriate ventilation methods, and improve the accuracy of CFD simulations.
Effects of ceiling fan and window exhaust on aerosol transmission risk during home quarantine situation
Authors: Cheung Toby , Tham Kwok Wai
Published: June 2023

SARS-CoV-2 has been recognized to be airborne transmissible. With the increased transmissibility leading to increasingly reported positive cases, home quarantine is adopted for the infected patients who are not seriously ill. However, the risk of household aerosol transmission is not well studied. We conducted tracer gas experiment to simulate the exhaled virus laden aerosols from a patient under home quarantine situation inside a residential testbed. The Sulphur hexafluoride concentration (SF6,conc) was measured both inside and outside the quarantine room under various scenarios including, (i) air-conditioning (AC) vs natural ventilation (NV), (ii) operation of ceiling fan, and (iii) operation of window exhaust fan. The ratio of outside-to-inside SF6,conc (O/ISF6) was an indicator for potential exposure of occupants in the same household. Our findings showed, without an exhaust fan, the in-room SF6,conc in AC settings was 4 times higher than in the NV scenarios. Meanwhile, we found the exhaust fan was effective in reducing the O/ISF6 in the AC scenarios (with or without ceiling fan), but its function was diminished in the NV setting with ceiling fan. We suspected the effectiveness of exhaust fan was reduced by air infiltration from other window openings in NV situation. Meanwhile, the operation of ceiling fan continuously pushing tracer gas outwards from the quarantine room through the door gap. Our results suggested that natural ventilation with windows open or switching on a window exhaust fan could reduce aerosol transmission risk from the quarantine room. This study provides useful evidence in recommending low risk ventilation strategies for home quarantine situations.
Energy performance of a hybrid DSF-inspired solar heating façade for office buildings
Authors: Bang Suyeon , Yoon Nari , Heo Yeonsook
Published: June 2023

Double-skin façade (DSF) is a passive design strategy that enhances building energy performance and improves indoor thermal comfort. In addition, DSF has been proposed as a hybrid façade that uses a cavity to preheat fresh air supplied to an air-handling unit (AHU) to reduce energy consumption for heating. However, to the authors' knowledge, there is no study about the design of DSF tailored for the hybrid system application yet. Therefore, this study focuses on the usability of DSF as a hybrid system and evaluates the performance. First, parametric analysis of the hybrid solar heating façade geometry and thermal properties of glazing and absorber materials was performed to identify the most influencing design parameters. Second, the multivariate linear regression (MLR) model was developed to predict the performance of all parameters comprehensively affecting the hybrid solar heating façade. Finally, the performance of various design alternatives for hybrid solar heating façade that provide the minimum fresh air supply was evaluated through case studies. The analysis results confirmed that the hybrid solar heating façade can reduce the heating energy due to the preheating effect by up to 38%.
Investigation of the Effectiveness of Infection Control Measures in the Dental Office
Authors: Yumino Saori , Hasama Takamasa , Kondo Koji , Koga Takashi , Watanabe Keisuke , Shoji Yoshio , Tanabe Tomoki , Arata Naoya , Fujii Kazuyuki , Ishigaki Yoshiki , Shibui Takeo , Kobayashi Ryutaro
Published: June 2023

Aerosol transmission is an important mode of COVID-19 (SARS-CoV-2) infection. Dentists and dental hygienists, who provide medical treatment and care in the oral cavity, may be exposed to expiratory aerosols of asymptomatic infected persons. To compare the effectiveness of devices in reducing the risk of transmission to dentists and dental hygienists, we conducted experiments in a dental treatment room at Nippon Dental University. The measurements were carried out in five cases: a) the basic case (conventional air conditioning), b) a case with the circulator placed in the center of the room and operated in high air flow mode, c) a case with a circulator placed behind the patient and operated in low air flow mode, d) a case with the circulator blowing from inside to outside, e) a case using an extraoral vacuum, and f) a case with a portable neck fan hanging on the dentist manikin. The results indicated that all measures were effective in reducing the risk of infection, and case e showed the highest reduction in aerosol concentration. However, because extraoral vacuums are expensive, it is important to reduce the risk as much as possible by selecting circulators or portable neck fans according to the budget of each hospital.
Efficacy of Energy Conservation Measures and Building Energy Intensity of a Multi-Building Complex in Malaysia
Authors: Tan Xian Yun , Mahyuddin Norhayati , Zaid Suzaini Mohamed
Published: June 2023

As Malaysia continues to develop at a fast pace, the number of buildings in this country rapidly increases. Commercial buildings which include office buildings are one of the three major energy consuming sectors, which includes industrial and transportation sectors. Most Malaysian government office buildings tend to consume energy inefficiently due to lack of energy optimization. This study aims to analyse the energy performance as well as the factors that influence energy consumption in government office buildings. The chosen buildings for this case study are six government office buildings located in Kuala Lumpur, the capital of Malaysia. In this study, literature review has been conducted on the common factors affecting energy consumption in office buildings. The energy consumption data of the buildings were collected and analysed by comparison among the buildings and the SketchUp software. The Building Energy Intensity (BEI) of each building was also calculated using the formula in MS 1525:2019. Literature review and results from the case study show that air-conditioning system is the major energy consumer in office buildings, followed by lighting system while other office equipment consumed the least energy. The findings also highlight that energy consumption in office buildings is affected by non-design factors such as building occupants’ behaviour, number of building occupants, outdoor temperature as well as passive design factors such as building orientation and window-to-wall ratio. Recommendations were derived based on the findings from literature review and the case study for best practices to optimize energy consumption in government office buildings in Malaysia.
Simulation of IAQ and thermal comfort of a classroom at various ventilation strategies
Authors: Zemitis Jurgis , Borodinecs Anatolijs , Sidenko Natalja , Zajacs Aleksandrs
Published: June 2023

It has been reported that there is a large issue regarding the IEQ in schools and classrooms as they often do not have a mechanical ventilation system or do not operate it to save on electricity bills. However, the measurements and reports from existing research indicate that the indoor air temperatures and CO2 levels are often way outside the recommended values and manual venting by opening windows during brakes is not sufficient. This has become especially alarming during the COVID-19 pandemic, as the virus can spread through the air and under-ventilated classrooms pose a great risk for the pupils located in them. In the scope of this paper, a classroom was simulated concerning IAQ and thermal comfort at various ventilation strategies. The simulation was used to determine the predicted thermal comfort at various locations in the classroom at different window opening areas and orientations. Based on the simulation results potential control strategies for window ventilation were developed. They take into account the changing location of persons and the threshold level of allowed deviation from optimal thermal comfort level to achieve the optimal IAQ as a compromise during the cold winter periods must be made. The results indicated that after 50-second-long natural ventilation at an outside air temperature of -3°C the thermal comfort level will be very low in most of the points of the classroom. None of the various window-opening strategies influences this much. The lowest achieved average PPD was 62.5% and it was in the case when one open window was open at 90° but in the case when two windows were open at 15 cm the average PPD was 98.7%.
Feasibility study of simplified pipe modeling for analyzing thermal performances of radiant heating and cooling systems
Authors: Seo Rosa , Choi Ji-Su , Kim Chul , Rhee Kyu-Nam
Published: June 2023

Energy-efficient radiant heating and cooling require surface temperature and thermal capacity analysis. Simplified pipe modeling is applied to save time and resources for numerical analysis when evaluating the radiant system. Therefore, this study investigated the surface temperature distribution and thermal capacity of a radiant system using simplified pipe modeling. To do this, a steady-state heat transfer simulation was performed using Physibel BISCO. The difference between detailed (circular) and simple (rectangular) pipe models and the effect of material thermal conductivity of various layers were analyzed in three types of radiant heating and cooling systems: Embedded Surface System (ESS), Thermally Activated Building System (TABS), and Cooling Radiant Ceiling Panels (CRCP). The simple and detailed ESS and TABS simulation results showed similar surface temperature and heat capacity in various materials. Also, the CRCP simple and detailed models for materials differed in surface temperature and heat capacity, especially when the pipe thermal conductivity was high. The CRCP simple model overstated surface temperature and thermal capacity, which needs heat resistance to solve this overestimation. Further studies are necessary to investigate the discrepancy with different dimensioning and operation conditions, such as water temperature and flow rate.
Development of an intelligent envelope system with energy recovery ventilation for passive dehumidification in summer and solar collection in winter
Authors: Chen Yulu , Ozaki Akihito , Lee Haksung , Choi Younhee , Arima Yusuke
Published: June 2023

With the aim of establishing a zero-energy housing (ZEH), an intelligent envelope system composed of a passive dehumidification and solar collection system (PDSC system) based on thermodynamic energy theory and an energy recovery ventilation (ERV) unit has been developed, abbreviated as PSE (PDSC & ERV) system, which can be expected to control the indoor hygrothermal environment by using renewable energy further to reduce the heating and cooling demand for the HVAC system. In this study, the measurement experiments were conducted in a wooden house equipped with a PSE system, and the temperature and humidity distributions in the rooms were assessed using thermohygrometer sensors. The field comparison experiments for the three systems (exhaust-only ventilation system, ERV system, and PSE system) were performed separately under various meteorological conditions in summer and winter. The measurement results in summer showed that the PSE system has a significant dehumidification effect compared to the exhaust-only and ERV-only ventilation systems and could effectively reduce the latent heat load caused by ventilation. The measurement results in winter indicated that the PSE system has the effect of heat collection and humidity control as well as reducing the sensible heat load originating from ventilation.
Building energy efficiency improvement using multi-objective optimization for heating and cooling VRF thermostat setpoints
Authors: Es-Sakali Niima , Kaitouni Samir Idrissi , Laasri Imad Ait , Mghazli Mohamed Oualid , Cherkaoui Moha , Pfafferott Jens
Published: June 2023

The variable refrigerant flow system is one of the best heating, ventilation, and air conditioning systems (HVAC) thanks to its ability to provide thermal comfort inside buildings. But, at the same time, these systems are considered one of the most energy-consuming systems in the building sector. Thus, it is crucial to well size the system according to the building’s cooling and heating needs and the indoor temperature fluctuations. Although many researchers have studied the optimization of the building energy performance considering heating or cooling needs, using air handling units, radiant floor heating, and direct expansion valves, few studies have considered the use of multi-objective optimization using only the thermostat setpoints of VRF systems for both cooling and heating needs. Thus, the main aim of this study is to conduct a sensitivity analysis and a multi-objective optimization strategy for a residential building containing a variable refrigerant flow system, to evaluate the effect of the building performance on energy consumption and improve the building energy efficiency. The numerical model was based on the EnergyPlus, jEPlus, and jEPlus+EA simulation engines. The approach used in this paper has allowed us to reach significant quantitative energy saving by varying the cooling and heating setpoints and scheduling scenarios. It should be stressed that this approach could be applied to several HVAC systems to reduce energy-building consumption.
Overheating vulnerability assessment of energy retrofit actions in a multi-apartment building in Podgorica, Montenegro
Authors: Pajek Luka , Košir Mitja
Published: June 2023

The study aimed to assess the overheating vulnerability of an existing multi-apartment building built in 1971 in Podgorica, Montenegro. The building consists of 80 apartments and is mostly still in its original state. Firstly, the building was modelled in EneryPlus, and a parametric study was performed with jEPlus. The energy need for heating and cooling was simulated using parameters such as thermal insulation level, window properties, external surface solar absorptivity, shading activation set-point, and natural ventilation cooling intensity. Moreover, the energy need was determined for four different climate periods, namely for the current and three future periods up to the end of the 21st century under the RCP8.5 climate change scenario. The total number of building models equalled 648 for each of the four climate scenarios, resulting in 2,592 simulated cases. After that, the overheating vulnerability score was determined using the minimax regret method and cooling energy need as a performance indicator. The best retrofit action was determined by identifying the most favourable combination of the overheating vulnerability and total energy need. The results deliver the appropriate energy retrofit actions to limit the increase in overheating risk and provide for climate change adaptation of the multi-apartment building stock in Montenegro.
Assessment of the impacts of window-to-wall ratio and overhangs on building energy performance – Kabul, Afghanistan
Authors: Karimi Mustafa , Chikamoto Tomoyuki , Lee Myonghyang
Published: June 2023

Windows have the potential to save energy in a significant way. Therefore, the analysis and optimization of the Window-to-Wall Ratio (WWR) play an important role in improving energy efficiency in buildings. Windows are always beneficial to utilize daylight and reduce lighting energy demand. However, solar heat gain is advantageous during cold days and disadvantageous on hot days. As the configuration of the window areas varies according to the geographical location, the objective of this study is to evaluate the impact of WWR on the energy performance of buildings in the cold semi-arid climate of Kabul, Afghanistan. In this study, various energy simulations were conducted for three types of building shapes (Square, Rectangle, and “L”-Shape) to determine the most energy-efficient proportion of windows and overhang sizes in different cardinal directions. Based on the simulation results, windows on south façades have notable energy-saving potential in Kabul's climatic conditions. However, increasing the window size on north, east, and west façade leads to an increase in the total heating and cooling energy consumption. The optimal WWR of the south façade window for square, rectangular, and “L”-Shaped is 0.7, 0.55, and 0.55, respectively. Additionally, the findings indicate that overhangs in all orientations slightly affect the total energy demand as they only reduce cooling load. The study concludes that optimizing the windows on the south façade reduces energy demand by up to 8.13% if no windows are provided in other directions, while the total energy consumption rises by up to 36% as the WWR on the north, east, and west façades increase from 0 to 0.8.
Comparative study of sol-air temperature models in the tropical island based on measured data
Authors: Xiao Guofeng , He Naping , Yin Kaili , Zhang Xiaojing , Xie Jingchao
Published: June 2023

The sol-air temperature is a hypothetical parameter to reflect the outdoor multi-field coupled thermal environments of air temperature, solar radiation, and long-wave radiation. The simplified model was proposed in code for thermal design of China which ignores the influence of long-wave radiation of sky and surrounding environment. However, the climate is characterized by strong radiation, high temperature and high humidity in tropical islands, and the underlying surface types are mostly sea surface. This may affect the applicability of sol-air temperature models. To explore the above issues, the Davis weather station and Kipp & Zonen solar radiation observation system were used to gather the meteorological and radiation data around the building, which is a case study building near the coastline in Sanya. Also, the dynamic temperature of the external surface of envelope and sea surface was captured. Then, the weather types were classified by clearness index, and the influence of sky and sea surface radiation on the sol-air temperature calculation of each orientation in different sky conditions is analysed. The results show that the sol-air temperature decreased by 1.07-2.44 ℃ on average considering the long-wave radiation of the sky and sea surface, especially in clear sky, with an average decrease of 1.49-3.85 ℃.